ALBERT

Beschreibung: Many estimates have been made of sperm production in various species, but in most cases examinations have been made infrequently or with irregular intervals between successive collections. Since during a period of sexual rest spermatozoa may accumulate in the epididymis, or with longer periods may undergo disintegration and absorption in the vas and ampulla (Simeone & Young, 1931), the number ejaculated at an particular collection will not necessarily reflect the level of sperm production in the testis. Moreover, there is the possibility that copulation may actually stimulate spermatogenesis. In horses, Chang (1943) found that more sperms were ejaculated if collections were made frequently and at regular intervals. In the present experiments an attempt has been made to determine the effect of frequency of collection upon the sperm production of rams, the collections being taken at regular intervals and for a definite period, in this case ten days.

Beschreibung: A laboratory study has been made of nitrification rates of the soil's own nitrogen, ammonium sulphate and certain organic nitrogen compounds. It is shown that nitrification in this soil is substantially normal, with no striking differences from that in soils of other arid regions.I am indebted to H. Greene and E. M. Crowther for access to their earlier unpublished work on nitrification in Gezira soil, and to O. W. Snow of this Service for advice during the course of this work.

Beschreibung: A method is presented for the preparation of a sensitive and diagnostic stained antigen for the detection of fowls suspected of infection by the organisms found in epidemic bacillary white diarrhoea (pullorum disease).Evidence is presented that an antigen prepared from organisms grown in a medium which provides for the peculiar growth requirements of the anaerobic organism associated with anaerogenic pullorum, is more sensitive than antigens prepared from organisms grown on media which lack these peculiar growth factors.A stained antigen has been prepared which is agglutinated by pullorum antisera in 15 sec. at 4°C. and in 6 sec. a t 15°C. and which is not agglutinated by normal sera in 5 min.The author wishes to thank the Directors of Messrs J. Bibby and Sons, Ltd., for permission to publish these papers.In particular he would thank Mr J. Pye Bibby for his keen interest in the investigations and for his loyal support throughout.In addition he wishes to thank Miss Margaret Davies for her assistance in the bacteriological investigations, and Miss Margaret Shafto for laboratory work and the compilation of relevant data.

Beschreibung: An experiment involving twelve pens of twenty-five pullets demonstrated that two types of dried potatoes compared favourably with cereals, as regards their effects on egg production, when up to 42½% of each product was included in the mash.The records of the experiment, as regards (a) the number of eggs laid in 12 months, (b) the mean weight of eggs during the year, and (c) the change in live weight during the year, were studied by analysis of variance, using the approximate method of Yates (1933) for obtaining standard errors of pen means from the variance within pens. Similar analyses of the number of eggs laid in the month were carried out for each month separately. The latter analyses indicated the months in which increased production was obtained from the superior rations, and showed that duplicate pens had reacted similarly to the experimental feeding. The results of the statistical analyses are set out in some detail as an example of method.

Beschreibung: 1. Dressings of 12–100 lb. borax per acre resulted in marked temporary ‘yellowing’ of bean seedlings. Dressings of 25 lb. or more depressed the stand and reduced the yield.2. Determinations were made to ascertain the distribution of boron within the treated plants and to measure the uptake of boron from the soil. The relevant figures are quoted in the text.

Beschreibung: Evidence is presented, based on feeding tests, that vitamin A metabolism is adversely affected when meat meal having a vitamin A consuming power in vitro is included in the diet of chicks.Evidence is presented, based on feeding tests, that when fish meal having no vitamin A consuming power in vitro is fed to chicks in a basal ration which produces negligible mortality, the addition of such fish meal to the ration does not appreciably increase mortality.Evidence is presented, based on feeding tests, that when fish meal having a vitamin A consuming power in vitro is fed to chicks in a basal ration which produces negligible mortality, the addition of such fish meal to the ration causes appreciable mortality.

Beschreibung: The main object of the present investigation was to test the inference from the results of previous trials that a diet composed substantially of cereal and weatings, with a small percentage of lucerne meal or grass meal, and supplying 7% of white-fish meal up to 90 lb. live weight and no protein supplement at all thereafter, should provide all the protein needed for the maximum rate of growth in bacon pigs and the production of carcasses of satisfactory quality, when fed at the rates shown in the feeding chart in Table 3.Two separate trials were carried out, and both the individual-feeding and group-feeding techniques were employed. In Trial I the control treatment A supplied the standard allowances of high-protein supplement, consisting of 10% of white-fish meal from weaning to 150 lb. live weight, and 5% of extracted soya-bean meal from 150 lb. to slaughter at about 200 lb. The white-fish meal in the rations of the pigs on treatment B was restricted to 7% up to 90 lb. live weight, and from this stage onwards the high-protein supplement was entirely omitted from the diet. The rest of the diet in both treatments consisted of barley meal and weatings, with a small percentage of lucerne meal, care being taken also to safeguard the animals against mineral deficiencies.

Beschreibung: Trichlorethylene-extracted palm-kernel meal is not an essential factor in the production of six-day disease.A comparison of the results of tests 1, 2 and 3 clearly indicates that under the same conditions and with similar chicks, some diets tend to produce six-day disease and some do not.

Beschreibung: 1. Substantial control of covered smut of wheat, Tilletia caries, was obtained when seed was treated with an approved organo-mercury seed disinfectant using both rotational and gravitational machines for mixing.2. Good control of leaf spot of oats, Helminthosporium Avenae, was also obtained, using an approved organo-mercury seed disinfectant and mixing grain and powder together in a model rotational-type machine.3. The model rotational machine gave an even mixing of grain and seed disinfectant with as few as forty-eight turns. Twenty-four turns was almost as effective but the mixing was much less even.4. The gravitational machine was not so efficient in producing an even mixing as the rotational machine as assessed by the control of covered smut of wheat.5. There was an indication that the rotational machine gave a better disease control.6. Improvement was effected in the efficiency of mixing with the gravitational machine by the addition of a felt lining to the feed hopper.

Beschreibung: Consideration of the composition of pig depot fats from the point of view of Callow's growth-rate theory (Callow, 1935a,b), shows that the theory appears to explain the iodine values of fats both of groups of animals and of depots of an individual pig. When, however, the fatty acid compositions of the fats are considered, the theory is untenable in respect of the depots of an individual pig. Differences in unsaturation between outer back fat, inner back fat, and perinephric fat are essentially determined by differences in the ratio of oleic acid to stearic acid, differences in linoleic acid content being inconsiderable.It can equally be shown that the growth-rate theory does not explain the results obtained by Hilditch & Pedelty (1941) for depot fats of sheep. Differences between different depots both of the pig and of the sheep seem to be characteristic of the species and cannot readily be altered by altering either the quantity or the quality of the diet.

Beschreibung: SUMMARYA method is described for economizing in the use of fertilizers on deficient soil by soaking the cereal seeds in nutrient solutions containing the deficient element at a sufficiently high concentration to supply a large part of the total requirements of the plants.The result of greatest potential practical importance was obtained on oats. Soaking oats in molecular tribasic potassium phosphate brought about an increase in yield from 17 to 25 cwt./acre (46 %) on phosphate-deficient soil at the cost of 13·6 lb./acre of the potassium phosphate (or 4·6 lb. P2O6) without the addition of any phosphate to the soil. There was a correspondingly large increase in the weight of straw. Nearly 75% of the P2O5 introduced in this way was recovered from the harvested grain. Sodium phosphate appears equally efficaceous for oats. Strikingly beneficial effects were also obtained on barley and wheat.

Beschreibung: SUMMARY1. The results of a study of sampling for ginning percentage in cotton variety trials are given. The investigation was undertaken to determine the most satisfactory method of obtaining the necessary ginning percentage factors for conversion of yield of seed-cotton to yield of lint.2. The material consisted of a widerange of strains derived from the jassid-resistant Upland, U4, planted out in trials of randomized block design, in different seasons.

Beschreibung: SUMMARYThe loss of viability of seeds of Chewing's Fescue Grass has been a serious problem to both the producers in New Zealand and the trade in the United Kingdom. It has been shown by Foy (1934) that seeds with a high moisture content (20 %) held at 30° C. deteriorated rapidly after 10–14 days and even more quickly at 40° and 50° C. Seeds with a water content of 13 % deteriorated more slowly but it was not until the water content was reduced to and maintained at 5 % that seeds retained their viability at 30°, 40° or 50° C. for 42 days. Even at room temperature (16–20° C.) the loss of viability occurred after 4–5 months at 20 % water content and after 8–9 months at 13 % but at 5 % water content there was no loss. Foy discusses the effects of temperature and humidity that may occur during transport; Hyde (1935) has examined the effect of heating seeds to 50°, 60°, 70°, 80° and 90° C. with a view to working out the conditions for artificial drying of the seeds before transport, and Lewis (1934) has found that, in some seasons, there was a marked loss of viability in storing these seeds in the United Kingdom.

Beschreibung: SUMMARY1. Sexually immature White Wyandotte pullets have been treated with gonadal hormones with the object of simulating those changes in calcium and phosphorus metabolism which normally take place during the fortnight or so before laying begins.2. It is shown that certain treatments of the sexually immature pullet with oestradiol dipropionate evoked hypertrophy of the oviduct and changes in blood calcium and phosphorus similar to those encountered in the normal laying pullet, but did not produce any significant increase in the rate of calcium or phosphorus retention.

Beschreibung: SUMMARY1. The physiological effects of severe hyperthyroidism on five sheep are described.2. Increases in pulse rate of more than 100% were observed. The increase in pulse rate was proportional to dosage with the exception of one sheep which had lesions on the chordae tendinae of the left ventricle.3. The heart, even though beating at this elevated rate, reacted normally to severe exercise, but there was a tendency for the sheep to carry out its normal functions at a slower rate so such large increases in pulse rate did not occur as the result of voluntary activity.4. Considerable cardiac arrhythmia was noticed in all hyperthyroid sheep.5. The relative increases in pulse rate of the cow and the sheep given iodinated casein of the same potency suggest that as between species dosage of iodinated casein is proportional to ‘metabolic body size’—the between species unit of basal metabolism—rather than to body weight itself. On this basis the stimulation of the sheep was between 1 and 4 times the dosage accepted as normal for the cow.6. Body temperatures increased in the most severely affected animals. Respiratory rates quadrupled in some cases.

Beschreibung: SUMMARYIn the investigation described, we have observed a t monthly intervals throughout gestation the changes taking place in a series of similar ewes, in lamb to the same ram, and each receiving the same standard diet.In following the live-weight growth curves of the ewes it was found that on a constant level of feeding the weight gains became greater during each succeeding month of pregnancy, and at corresponding stages were larger for ditocous than for monotocous ewes. This was found to be due to the fact that, although on our diet the ewes did gain slightly in actual body weight, the main increases in live weight resulted from the growth of the gravid uterus itself, and this increases in weight far more rapidly in the later stages of gestation, and is also heavier where twins are carried.

Beschreibung: SUMMARYComparative digestibility trials have been carried out on hays top-dressed with nitrogenous fertilizers 8–13 days before cutting and on similar hays which were not top-dressed.The top-dressing resulted in an increase of 2·0% crude protein and 1·2% true protein.The digestibility of the protein was significantly higher in the top-dressed hays and no other constituents were affected.The protein equivalents in hay dry matter were increased from 4·4 to 6·0% by the top-dressing.

Beschreibung: SUMMARYEvidence is provided to prove that the nutritional malady, Coast Disease, which affects sheep de-pastured without change on the shell-sand littoral of South Australia is due solely to the inability of the pastures to provide the quantity of cobalt and copper necessary to fulfil the nutritional requirements of grazing sheep.An experiment started in 1936 in which five evenly matched groups of young cross-bred ewe hoggets were dosed thrice weekly with cobalt, copper, cobalt plus copper, and with cobalt plus copper together with iron, manganese, zinc and nickel is described.

Beschreibung: A comparison of four methods for the determination of the exchangeable hydrogen content of soils was carried out on 157 soils, from twenty-one profiles and representative of four soil types.The methods employed were those of: (1) Hardy & Lewis, (2) Mehlich, (3) Bradfield & Allison, (4) Schofield.The best agreement was obtained between methods (2) and (3) which are also the simplest to apply.A positive correlation was found between low values given by method (1) and the organic matter content of the soil.

Beschreibung: 1. A method is described whereby absolute changes in the organic and mineral constituents of cacao leaves during decomposition may be followed.2. On a basis of their behaviour during decomposition, the components measured fall naturally into three groups. The first group comprises lignin, total protein, resistant protein, dilute-acid protein, concentrated-acid protein and nitrate-nitrogen; these exhibit an absolute increase during decompositión. The second group, represented by hemicelluloses, cellulose and pentosans, all show a downward trend, the decrease being most rapid at the outset. Alcohol- and ether-soluble substances constitute the third group and are characterized by a very rapid decrease during the first few weeks of decomposition.3. A large amount of material soluble in dilute acid which is neither protein nor reducing sugar is not accounted for; this on a carbon basis constitutes over 50% of the dilute acid hydrolysable fraction. The trend of this fraction is somewhat similar to the carbohydrate fractions. It is pointed out that this fraction should not be neglected in a proximate analysis of decomposing organic matter.4. Potassium exhibits a very rapid decrease at the onset of decomposition, and the trend is closely parallel to the alcohol- and ether-soluble substances. At times of heavy leaf fall there is consequently a marked manurial effect which may amount to the equivalent of 1 cwt. of sulphate of potash per acre.

Beschreibung: The bacterial syndrome encountered in epidemic bacillary white diarrhoea of chicks (pullorum disease) is initially one of invasion by faecal type organisms, this is followed by invasion by anaerogenic B. pullorum.Evidence is presented to show that ostensibly pure cultures of anaerogenic B. pullorum, consist of two organisms, a true aerogenic B. pullorum in symbiosis with an anaerobe, morphologically of the welchii type.Evidence is presented to show that variation in fermentation reactions of ostensibly pure cultures of anaerogenic B. pullorum depend upon the degree of symbiosis exerted between the anaerobe and the aerobe and this degree of symbiosis is greatly affected by methods of cultivation on solid media.It is proposed that the ovarian blight peculiar to adult hens which are carriers of bacillary white diarrhoea infection is caused by putrefaction of ovarian material in vivo by the activities of a morphologically welchii type organism.It is proposed that B. pullorum exists in one form only, namely, the aerogehic form, and that this organism is a potential pathogen only.

Beschreibung: A feeding test performed on Hanns Hall Farm chicks demonstrates that a diet conducive to intestinal putrefaction fed to chicks after 14 days from birth initiates an epidemic of bacillary white diarrhoea (pullorum disease).If is proposed that measures for the control of epidemic bacillary white diarrhoea of chicks (pullorum disease), which consist of the detection and removal of reacting hens from the flock by means of a diagnostic and sensitive antigen, cannot be effective unless accompanied by an alteration in nutrition for the purpose of reducing intestinal putrefaction.Experiments at this laboratory show that the agglutination test for bacillary white diarrhoea cannot differentiate between fowls which produce diseased chicks and fowls which produce chicks resistant to disease.Experiments at this laboratory show that B. pullorum as a potential pathogen does not remain viable to an extent that it is able to produce bacillary white diarrhoea in chicks from an incubator or brooder which has held diseased hatches or broods, respectively.

Beschreibung: Average lactation curves have been prepared from selected animals in a group of heifers treated for 60 or 100 days with stilboestrol or hexoestrol tablet implants. A treatment period of 100 days appears to give poorer results than one of 60 days. The optimum duration, on the average, is probably about 75 days, but seems to depend upon the way lactation develops—which bears no obvious relationship to the amount of oestrogen absorbed.A rise in yield follows tablet removal whether this is done while the yield is still rising or after it has begun to decline. Yield in an induced lactation may fall very far short of the animal's inherent capacity, but comparison between induced lactations and those at subsequent calvings shows that it may very nearly approach what would be a normal yield.A heifer which was treated twice did rather less well in her second induced lactation.Breeding histories of a number of implanted heifers are outlined. They were all animals which had failed previously to get in calf. 5–10% (without further treatment) did not return to an ovulatory cycle. About 70% of anatomically normal heifers got in calf, the service rate being about 2·6. A rather high incidence of abortions may be a feature of a recovery period from treatment, but may have been due to selection of animals with such a tendency.

Beschreibung: 1. By premature harvesting, as early as 5 days after fertilization, dwarf grains are obtained which will germinate readily and produce normal plants, even though grain size may be only 10% that of fully developed grain. Such plants tend to attain the same final size as those from mature grain. This paper deals with the growth under field conditions of dwarf grain with regard to survival during the winter, and final yield.2. Pot cultures with vernalized winter and spring varieties of rye, wheat, and barley have shown that the high growth rate characteristic of dwarf grain is not confined to the vegetative phase of growth, but is also manifested after the ear has developed. The fact emerges that dwarf grain can be successfully vernalized.3. A field trial is described using three size classes of grain (mature, medium, dwarf) with mean grain weights of 33·93, 23·56 and 10·23 mg. respectively. These were sown (i) at sowing rates of 2 and 3 bushels per acre, and (ii) at uniform spacings of approximately 200 and 300 grains per 9 ft. row. A subsidiary experiment with spacing of 1 ft. was also carried out.4. All classes of grain germinated well and survival during the winter was uniformly high in the equally spaced plots; with the close spacing of the dwarf grain at 2 and 3 bushels per acre (plots 11 and 12) percentage survival was somewhat reduced.5. The effect of grain size and spacing on time of flowering was negligible.

Beschreibung: 1. Experiments were made on the respiration of bran at different moisture levels using a continuous absorption apparatus in which the humidity of the air-stream was adjusted to be at equilibrium with the respiring bran. The rate of respiration was accelerated with increasing moisture content and was very rapid deterioration due to the high respiration rate and microbiological damage.2. Experiments were made on the storage of bran at known moisture contents in closed tins in the laboratory and also in sacks kept under farm conditions. The total nitrogen content of the bran stored in the tins appeared to increase during storage. From similar increases in total phosphorus, it is clear that the increase in total nitrogen was caused by a loss of dry matter from the stored feeding stuff, a fact which was further demonstrated by the loss in dry weight of the sacks of bran with attributed to two causes: (1) the respiration of the plant cells still active in the bran itself, and (2) the respiration of developing micro-organisms. It is evident from these experiments that fresh bran, free from insect infestation and stored at a moisture content of less than 13%, will have a very low respiration rate and will, therefore, not be liable to heating. Bran of 15–19% moisture content respires at a much faster rate and the time for which such material can be stored with freedom from heating or other types of deterioration will be limited.

Beschreibung: 1. Experiments were carried out to determine the period of survival of spermatozoa in the genital tract of the cow.2. No reliable results were obtained by searching, post-mortem, the genital tracts of two cows and three heifers killed at various intervals after insemination.3. An attempt to induce ovulation at a definite time to which insemination could be related, in order that the survival time of the spermatozoa might be determined by the recovery of the ova post-mortem, was not successful. Of four cows and one heifer given pregnant mare's serum followed by pregnancy urine, one ovulated. To one animal, where a large follicle was present in one ovary, pregnancy urine was given. Ovulation occurred but could not be definitely attributed to the pregnancy urine.

Beschreibung: 1. Losses of incorporated non-protein nitrogen compounds from stored cubes have been determined. The loss of incorporated urea was very small provided moulding did not occur. The loss of incorporated ammonium bicarbonate was large, amounting in all to some 50–60%.2. The effects of the size of the cubes and of the nature of the container on nitrogen losses are discussed.

Beschreibung: 1. The occurrence of stripe smut of rye, Urocystis occulta (Wallr.) Rab. in Great Britain is recorded.2. Control of seed-borne infection by disinfecting seed prior to sowing with an approved organomercury seed disinfectant has been shown.3. Experiments have confirmed that the disease may be soil-borne.4. With the increase of the acreage of rye grown in Great Britain it is suggested that seed should be treated with an approved organo-mercury seed disinfectant as a preventive measure.

Beschreibung: 1. Data are presented for the chemical and botanical compositions of ryegrass seed and various by-products of the ryegrass seed cleaning industry.2. Digestibility data are presented for a more limited range of samples of ryegrass seed, ryegrass seed cleanings and, for comparative purposes, of certain by-products of the milling of oats.3. Ground high quality perennial ryegrass seed has a chemical composition and digestibility comparable with that of oats.4. Ground rough (i.e. uncleaned) perennial ryegrass seed has a chemical composition and digestibility such that its starch equivalent is 90–95 % of that of oats.5. Ground bulked ryegrass seed cleanings has a starch equivalent of about four-fifths that of oats and is comparable in feeding value with better grades of oat feed, i.e. those containing not more than about 20 % of fibre.

Beschreibung: From time to time during the course of the present war, pig feeders have reported that they have experienced considerable difficulty when making use of extracted palm-kernel meal as a major constituent of the rations of bacon pigs. This has been attributed partly to the lack of palatability of the extracted meal, which leads to a reduction in food consumption and a consequent depression in the rate of live weight increase, and partly to its high fibre content, which causes the ration to be somewhat bulky and of lowered digestibility and nutritive value. The present experiments were designed to throw light on these somewhat contentious matters, since little guidance is to be obtained from the scanty references to this subject in the scientific literature dealing with animal nutrition.

Beschreibung: 1. The fertility records of two groups of bulls, one group used for controlled service, and one group used for free service, were compared over a period of one year.2. The fertility of the free-service group was consistently better except during the months of December, January, February and March.3. The difference in fertility between the two groups was correlated with the varying length of the oestral periods of the cows at different seasons of the year.4. It is suggested that the higher fertility in the free-service group was due to a closer relationship of service to the end of heat and thus to ovulation.

Beschreibung: SUMMARYTen fully grown Border Leicester-Cheviot ewes were divided into two groups of five; the heavier ones being about 150 lb. live weight, and the lighter ones about 70 lb. The former were placed on a low plane of nutrition, and the latter on a high plane. As the weights changed by successive amounts of 20 lb. animals were killed and dissected, and their organs and tissues weighed.

Beschreibung: SUMMARY1. Pot and field experiments were made to compare the effects of thiosulphates and sulphur on the incidence of manganese deficiency in oat, beet and pea grown in two manganese-deficient soils.2. The addition of sodium or calcium thiosulphate to oat plants growing in a manganese-deficient fen soil in boxes markedly reduced symptoms of ‘grey speck’ and increased the soluble manganese content in the leaf tissues, but the effect was transient.3. The growth of beet in this soil in clay pots was improved by the addition of thiosulphates, and also by painting the exterior of the pots with bitumen paint or by covering the surface of the soil with a thin layer of sand. The thiosulphate treatments increased the manganese uptake by the plants and reduced the symptoms of manganese deficiency, particularly when applied to pots painted with bitumen paint.4. Field experiments with an old garden soil deficient in manganese showed that thiosulphate treatments increased the manganese uptake of beet. Placement treatments were more effective than broadcast treatments and greatly improved the growth of beet and reduced or eliminated manganese-deficiency symptoms, without producing any change in soil pH.

Beschreibung: SUMMARY1. A study of different methods of staple-length measurement of material from a cotton variety trial, of the comparative accuracy of three persons' measurements and of the number of seeds which it is necessary to measure in order to achieve various degrees of accuracy in the determination of differences in variety trial and single plant material is described.2. If, in making single plant selections, the breeder is satisfied with a level of significance of P =0·1 when using a sample of only five seeds per plant, he would be justified in discarding material falling one and a half millimetres below the standard of staple-length at which he was aiming.

Beschreibung: SUMMARY1. Metabolism experiments have been made with five sheep fed iodinated casein in doses sufficient to give symptoms of hyperthyroidism, ranging from moderate to severe. Two comparable sheep were included to serve as controls.2. The same ration was used throughout each experiment, and it was found that the digestibility of its dry matter and of its crude protein content declined when the sheep were made hyperthyroid. This was due to increased peristalsis.3. The treated sheep lost body N when iodinated casein was given, the loss being proportional to dosage. Calculations indicated increases in the endogenous catabolism by up to 120%, and also increases in deamination.4. There was an increased excretion of urea and ammonia during hyperthyroidism, the latter being associated with a decrease in the plasma carbon dioxide combining capacity.5. Purine catabolism was accelerated by more than 50% in some sheep. Starvation of one sheep did not depress nucleoprotein catabolism as it does in the normal sheep.

Beschreibung: SUMMARYMoisture content and temperature are of first importance in the storage of seeds. Seeds are usually stored in porous containers like sacks and paper bags, and their water content fluctuates with the humidity of the surrounding atmosphere. In sealed chambers, on the other hand, the humidity of the atmosphere will be determined by the water content of the seeds and, with different kinds of seeds in an enclosed space, an exchange of water will occur until equilibrium has been reached. This does not mean, however, that different kinds of seeds, or even different samples of the same kind will have exactly the same final water content, since the water content/humidity relations are affected by differences in structure, chemical composition and previous drying treatment; it is permissible, however, for practical purposes, to ignore the slight differences which occur between samples of the same kind of seed.

Beschreibung: SUMMARYThe available data on calcium, phosphorus and carbonate balance experiments with laying and non-laying birds have been collected and condensed. From this condensed data the following relationships have been derived:(1) Calcium excretion is a function of calcium intake.(2) Phosphorus excretion is a function of phosphorus intake.(3) Carbonate excretion is a function of carbonate intake.(4) Carbonate/calcium ratio of the excreta is a function of carbonate/calcium ratio of the intake.(5) Calcium/phosphorus ratio of the excreta is a function of calcium/phosphorus ratio of the intake.

Beschreibung: SUMMARYThe effects of cobalt deficiency and of varying degrees of copper deficiency in young sheep were investigated.Five of six evenly matched groups of hoggets aged about 8 months when transferred to the deficient pastures were supplemented with the equivalent of 1 mg. Co/day, 10 mg. Cu/day, 1 mg Co + 1 mg. Cu/day, 1 mg. Co + 5 mg. Cu/day, 1 mg. Co + 10 mg. Cu/day, respectively, administered thrice weekly as a drench; the sixth group was untreated.All individuals that received no cobalt developed typical symptoms of cobalt deficiency and most of them died within a year. After 11 months the remaining cases were removed to the laboratory. They were then in the advanced stages of the terminal cachexia.

Beschreibung: SUMMARYThe metabolism trials described in the present communication were undertaken with the object of testing the conclusions arrived at in farm-scale feeding trials, designed in accordance with the requirements of the modern statistical lay-out, respecting the minimum protein supply needed to support the maximum rate of growth in bacon pigs.

Beschreibung: 1. The characters of the semen of twenty-one bulls were compared with their fertility as expressed by the service rate—the number of services required for each conception.2. It was found that, on the basis of the density of the semen, the total number of spermatozoa ejaculated, the motility and change in pH of the semen on incubation at 37° C, the animals could be divided into a higher fertility group with service rates from slightly more than 1·0 to about 3·5, and a lower fertility group with service rates from above 3·5 to ∞. Totally sterile animals could be detected.3. It is suggested that other factors than the quality of the semen can vary fertility so as to give service rates at different levels from 1·0 to about 3·5. Below a certain level of semen quality fertility appears to be impaired no matter what other factors operate.4. No relationship could be detected between the percentage of abnormal spermatozoa ejaculated and the service rate.5. Standards for use in diagnosis of fertility are suggested.

Beschreibung: SUMMARY1. The importance of uniform production of herbage for crop-drying is emphasized.2. A replicated experiment is described which compared four crops, two annuals and two leys under four manurial treatments which included a control and three applications of fertilizer (3½ cwt. ‘nitrochalk’) distributed during the season in three ways.3. Vetches yielded 2500–3000 lb. dry matter per acre of 28–30% crude-protein content in two cuts.Barley yielded 2500–3000 lb. dry matter per acre of 18–21% crude protein in five to six cuts.Leys yielded 4000–5000 lb. dry matter per acre of 15–18% crude protein in four cuts in their first year, and 5000–6000 lb. dry matter per acre of 15–18% crude protein in five cuts in their second year.

Beschreibung: SUMMARYBy measurement of single fibres from tattooed squares the variation in hip region mean cross-sectional area, mean fibre length and area of skin covered by fibre substance in a small flock of Romney sheep has been studied for a few years—see Part I.We find that under good growing conditions the area of skin covered by fibre is a constant percentage of the skin area for all sheep in all years. The number of fibres per unit area varies from sheep to sheep, and the mean cross-sectional area is inversely proportional to the number of fibres per unit area. The mean length/day is a constant for all sheep. When conditions are unfavourable the percentage of the skin area covered by fibre on a particular sheep falls below the good growing conditions percentage by an amount that is smaller the bigger the skin expansion ratio, but is greater the worse the season.

Beschreibung: SUMMARYThe effects of copper deficiency and of copper excess on mature Merino and Border-Leicester ewes were studied experimentally over a period of 3½ years with five evenly matched groups of each breed which were all depastured together as one flock on terrain where sheep develop cobalt and copper deficiency. All were treated with the equivalent of 1 mg. Co/day. Copper was administered thrice weekly in doses which provided for individuals of the respective groups the equivalent of nil, 1, 5, 50 and 100 mg. Cu/day.All of the individuals that received only cobalt became anaemic; they lost weight and developed marked symptoms of copper deficiency.The supplement of 1 mg. Cu/day was sufficient to delay the onset of these symptoms, but it failed to increase significantly the concentration of copper in the blood and it was insufficient to ensure normal myelin formation in the central nervous system of lambs born of the ewes which had received this treatment for 2 years prior to mating.

Beschreibung: SUMMARYThe writers are at present engaged in carrying out investigations into the relative supplemental values of the proteins in certain feeding stuffs that are commonly used to correct the protein deficiencies, in respect both of amount and quality, of the cereal grains and their by-products. As a preliminary to this work, it was necessary to obtain information about the digestibility of these protein supplements and their content of digestible protein and ‘total digestible nutrients’.

Beschreibung: Seasonal variation in the reproductive capacity of the bull was studied during a 27-month experimental period at the Experimental Station. There are a total of 1049 ejaculates for this period. Supplementary data for other periods on the Experimental Station and for two other large farms practising artificial insemination are also included.Highly significant individual and monthly differences were noted during the experimental period for the density and motility of the sperm, the pH of the semen and for the percentage of ejaculations performed. The seasonal variation in semen is marked, but there is considerable variation in different years between bulls and between farms in the periods of maximal and minimal types of semen and in seasonal trends.The relationship between such variation and climatic and nutritional conditions is discussed. There appears to be a basic seasonal rhythm in bull semen associated with climatic factors, warmer conditions causing stimulation and vice versa. Nutritional factors may, however, modify this rhythm. The relationship between seasonal variations in semen quality and fertility is discussed.

Beschreibung: Evidence is presented, based on feeding tests, that at Hanns Hall Farm it has been impossible to control bacillary white diarrhoea of chicks (pullorum disease) by blood testing when foods of c. 20% protein content have been fed as the sole diet of chicks.Evidence is presented, based on feeding tests, that at Hanns Hall Farm epidemic bacillary white diarrhoea (pullorum disease) has occurred in brother chicks when fed foods of c. 20% protein content and that epidemic bacillary white, diarrhoea has not occurred in sister chicks which have been fed crushed oats for the first 72 hr. and thereafter have been fed a diet of c. 14% protein intake.Evidence is presented, based on feeding tests, that at Hanns Hall Farm epidemic bacillary white diarrhoea (pullorum disease) not only did not occur in sister chicks in which B. pullorum had been demonstrated to be present in one of their number, but also epidemic bacillary white diarrhoea failed to develop despite the lack of hygienic precautions when these chicks had been placed in an uncleansed brooder from which the survivors of a severe epidemic of this disease had just been removed, and when they were brooded adjacent to chicks which suffered severe mortality from the disease, thereby undergoing all the chances of infection by wide dissemination of B. pullorum within a small area.

Beschreibung: In his observations on six-day disease, Taylor (1944) reported that the chicks which died on his preliminary experiments gave negative results on bacteriological examination.Many workers hold that for routine examination of poultry, a quick, convenient and inexpensive method of detecting certain specific bacterial infection is to inoculate slopes of nutrient agar with liver or other tissue, and incubate at 37° C. It is claimed that some organisms often grow in pure culture from diseased chicks, and that this method is especially suitable in the detection of S. pullorum or S. gallinarum infections. The resultant growth can be washed off in saline solution and tested by specific agglutinating sera or by testing on certain carbohydrates.

Beschreibung: 1. Data for the composition and digestibility of certain by-products of the ryegrass seed cleaning industry are presented in amplification of data already published.2. It is shown that the ‘hairgrass’ fraction of ryegrass seed cleanings has a starch equivalent somewhat superior to that of pure ryegrass seed or oats, and that this may be ascribed in all probability to its content of ratstail fescue seed.3. It is shown that the ‘flatweed’ fraction, consisting chiefly of buttercup seed, has a starch equivalent, on a dry-matter basis, about three-quarters that of oats or pure ryegrass seed, and that it is, in spite of a relatively high content of digestible oil, among the least valuable constituents of the cleanings, apart from dust, straw and other worthless material.4. Commercial Yorkshire fog seed is shown to have a feeding value comparable to that of pure perennial ryegrass seed.5. Some data are presented regarding the inorganic constituents of ryegrass seed and ryegrass seed by-products.

Beschreibung: The fatty acid composition of the back fats of pigs whose basic diets were buttermilk or skim milk have been determined by ester-fractionation, and the results are compared with those of previous workers. Pigs whose diets were supplemented with copra contained up to 13 mol. % of myristic acid, with smaller amounts of lauric acid.Experimental evidence supports the view that dietary linoleic acid is assimilated to a greater extent by slow-growing than by fast-growing pigs. Dietary lauric and myristic acids, however, appear in greater proportions in the depots of fast-growing, as compared with slow-growing pigs.The di-, and polyethenoid C18 acids of the fat of unsupplemented milk-fed pigs appeared not to contain appreciable amounts of linoleic acid.

Beschreibung: Six-day disease of chicks is a disease of intestinal putrefaction, and may be fostered by any ration which contains the following:(a) Animal proteins which show evidence of putrefaction.(b) Excess of fibre, or sponge-like fibre such as palm-kernel meal or sugar-beet pulp, which assist in the proliferation of putrefactive microbes.(c) Residual oils which destroy vitamin A.(d) Starch or carbohydrate insufficient to maintain an acid reaction to the lower end of the intestines.

Beschreibung: While numerous studies have demonstrated the essential role of magnesium in the normal development of plants, the information as to the soil conditions governing the availability of this nutrient is relatively limited. In general it is considered that a true lack of magnesium in the soil, such as might result from leaching or overcropping, is the main cause of magnesium deficiency in plants. This aspect of the problem has received considerable attention (Imp. Bureau, 1940). It has become evident in recent years, however, that the absorption of magnesium by plants may be depressed under the influence of an excess of other nutrients, notably potassium and calcium, in the soil. In some instances this has been noted to result in the onset of magnesium deficiency in plants, despite an apparently adequate concentration of this element in an easily available form in the soil as shown by chemical methods.The literature having a bearing on the inducement of magnesium deficiency in this manner has been reviewed by Walsh & Clarke (1944). These workers, from a study of magnesium deficiency chlorosis in tomatoes, showed that it was induced by heavy dressings of potassium causing a depression in magnesium uptake. While the effect of potassium alone in this respect was sufficient to induce the deficiency, it was also found that the sulphate radical played a prominent part. Where potassium was added other than in the form of the sulphate salt, the onset of the chlorosis was retarded and the symptoms were reduced in severity.

Beschreibung: 1. The results of two trials involving twenty-four pigs did not provide a clue to the observed craving of pigs for metallic copper.2. There seems to be no advantage in supplementing a normal diet for fattening pigs which contains about 5 p.p.m. of copper with copper given in form of a solution of copper sulphate. The addition of a mixture of copper sulphate, manganese sulphate and iron pyrophosphate to the same normal diet had also no effect on the rate of growth of the pigs and their food consumption.3. The haemoglobin and copper contents of the blood appeared to be unaffected by the addition of copper to the diet. The copper content of the livers showed a tendency to be higher in the livers of the pigs receiving the copper supplements.

Beschreibung: An analysis of the data from the continuous manurial experiment in Woodlands Field, Craibstone Experimental Farm, Aberdeen, has demonstrated the effects of fertilizers and of rainfall on the yields of various crops grown on a six-course rotation plan with a basal application of dung to the roots. The soil is a dark brown medium loam of which the parent material is ‘drift’ from the grinding down of granite and metamorphic rocks and is typical of a large class of glacial soils in the north-east of Scotland.Of the three major nutrients nitrogen gave the largest mean response on every crop except hay. The hay yield was benefited least by nitrogen and most by potash. The effect of nitrogen was to depress slightly, but not significantly, the total production of the ley for the 3 years. Potash, on the other hand, significantly improved the yield of hay as well as of the aftermath and the following ‘pastures’. The phosphate and potash responses were approximately equal in respect of barley, oats and potatoes. Turnips, swedes and potatoes responded similarly to potash, but in terms of dry matter the response was markedly higher for potatoes.Superphosphate proved more effective than ground mineral phosphate on every crop except turnips. Further study of the data revealed interesting differences between the crops in respect of their capacity for utilizing ground mineral phosphate. Oats gave negligible responses to mineral phosphate throughout the experiment.

Beschreibung: 1. An experiment was performed to consider the porosity of egg shells, and the influence of different levels of dietary calcium upon this factor.2. A method was devised for measuring porosity under standard conditions, and the values so obtained are referred to as porosity coefficients.3. The low calcium diet soon led to the cessation of egg production. The few eggs laid showed a tendency to increasing shell porosity as the end of laying approached. On the average these shells had much higher porosity coefficients than shells produced on a normal calcium diet.4. The high calcium diet had no apparent ill effects on two birds, but the other two laid many abnormal eggs. Porosity coefficients in this group were, on the average, lower than in the normal calcium group, but not significantly so. Egg production was as good as on a normal calcium diet.5. The porosity coefficients were significantly higher in period 2 than in period 1, when birds were fed the normal calcium diet throughout; egg production also fell in the second period.6. Eggs other than the first in a clutch do not differ in porosity, but the first egg has a significantly lower porosity coefficient than the remainder. A possible explanation of this is suggested.

Beschreibung: The average numbers of females of all ages (herd size) in pedigree herds of Jerseys, Guernseys, and Red Polls in 1939 were found to be 25, 22 and 42 respectively. Of the herds listed, 15–20% made no herdbook entries and were of much smaller than average size. Excluding these, the average numbers become 29, 26 and 49. The number of females entered in the herdbook during 1939 was about 20% of the total number of females of all ages. The same proportion was found in all herd size groups except the smallest where it was lower. As a general guide, therefore, to breed and regional differences in herd size in all the major breeds, the average number of herdbook entries of females has been multiplied by 5.

Beschreibung: Carrots of Chantenay type wefe grown in cultures of a black fen soil shown by analysis to be deficient in phosphate but normal as regards potash. When phosphate was absent, the cotyledons, and sometimes the whole of the foliage, were dark bronze in colour. There was a statistically significant increase in yield following applications of phosphate, but a tendency for applied nitrogen and potash to diminish yield.We thank F. Shaw, Esq., N.D.H., of the Cambs. C.C. Staff for Agricultural Education, for his assistance in obtaining the fen soil used in this experiment.

Beschreibung: SUMMARYAn experiment using eight pens each of twenty-five pullets was conducted to investigate the suitability of sesame cake meal as a protein concentrate for laying pullets. In meal mixtures supplying equal amounts of crude protein, sesame cake meal gave slightly lower production than fish meal and earthnut cake meal, but the differences were of doubtful statistical significance. Body weights appeared to be maintained less well on sesame cake meal, but only by an unimportant amount.The authors thank Prof. R. G. Baskett for his advice and constructive criticism, and Miss M. E. Osborne for the care and attention devoted to the management of the pullets.

Beschreibung: SUMMARYChanges in the percentage of dry matter, sugars, starch and nitrogen present in Arran Banner and Majestic potato tubers during storage in clamps until July or later were studied in two seasons. In the first season, the ascorbic-acid content and the distribution of nitrogen between three fractions (insoluble, soluble coagulable, soluble non-coagulable) were also determined. In the second season, weighed samples of tubers were introduced into the clamps, so that changes in absolute amounts of the different constituents present in the tubers or sprouts could be measured. The effects of removing or retaining the soil cover on the clamps after early April were compared.

Beschreibung: SUMMARYThe changing of treatments during the course of an experiment is discussed both from the point of view of designing trials in which changes are anticipated and of modifying trials that have fulfilled their original purpose. Cases are distinguished according to whether the interactions of original and new treatments are or are not important and recommendations are made for each case.We are indebted to Miss J. M. S. Thom for preparing the diagrams fot publication.

Beschreibung: SUMMARY1. A method is described whereby fructose content and fructolysis can be assayed accurately in small samples of semen. The advantages of this method lie in its simplicity, accuracy and practical convenience as a tool for the assessment of semen quality, applicable also under field conditions.2. The content of fructose in fresh semen depends upon the secretory function of accessory glands which is influenced directly by the activity of the male sex hormone. A low level of seminal fructose may coincide with other symptoms of hormonal malfunction and poor quality of spermatozoa. A high level of seminal fructose indicates satisfactory functional ability of the accessory glands, but it does not necessarily coincide with high quality of spermatozoa as expressed in terms of density and motility.3. The normal level of fructose in fresh semen undergoes frequent fluctuations which can be observed if semen collections are made from the same individual at different times. Considerable variations in the sperm/fructose ratio may also occur in the semen of the same individual as illustrated by the results of an ‘exhaustion test’.4. Fructose disappears from semen incubated in vitro. The rate of fructose disappearance forms a convenient measure of sperm fructolysis. The normal rate of fructolysis in bull semen is 1·4–2 mg. fructose per 109 sperm cells in 1 hr. at 37° C. At this high level it can be maintained until almost the whole reserve of fructose has been exhausted. Azoospermic and necrospennic semen, as well as that from vasectomized animals, are unable to utilize fructose. A reduced rate of fructolysis is found in low quality semen of subfertile and infertile animals.5. The conditions of sperm survival in semen incubated in narrow tubes as used for the fructolysis test as well as for storage of semen in the practice of artificial insemination, are almost purely anaerobic. Under such conditions the survival of spermatozoa must largely depend upon fructolysis and not upon respiration.

Beschreibung: SUMMARYIn the investigation described in this third part of the work, we have studied the effect of imposing two extreme levels of diet upon the pregnant ewe during two periods, one of early and one of late, gestation. In order to build up a comprehensive picture of the effect of these treatments we have been concerned, first, with the changes that they have wrought in the tissues and organs of the mother's body; secondly, with the effect upon the growth and development of the genital tract and its major components, and lastly with the way in which the growth of the tissues and organs of the foetus have responded to the different nutritive levels. While the latter has been our primary concern, the former have been studied in some detail so that we may view the effects produced as a whole, and gain an understanding of any competition that may have occurred between maternal and foetal tissues.

Beschreibung: SUMMARY1. Picton, a winter-hardy variety of oats selected from the cross Argentine x Grey Winter, contains plants which have irregular meiotic divisions.2. Two types of irregularities were observed: first, univalents and the products of their division; and secondly, bridges and fragments at both first and second divisions.3. Plants selected for a low frequency of irregularities produced offspring with a low frequency of irregular divisions. On the other hand, plants with regular divisions were also obtained from parents which had a high frequency of irregularities.4. It is pointed out that the genetical effects of bridge chromatid formation and breakage is the production of gametes deficient for chromosome segments. There is some evidence that chlorotic plants are produced when such deficiencies become homozygous.5. It is suggested that the meiotic irregularities produce a certain degree of heterozygosity which may make Picton more adaptable, and at the same time give it a certain degree of hybrid vigour.

Beschreibung: SUMMARY1. The ventilation of two byres, one of large (1248 cu.ft.) and one of small (567 cu.ft.) cubic capacity per cow, was studied. The CO2 concentration in the atmosphere was used as a measure of the rate of air change and the dry katathermometer to determine the cooling power of the atmosphere. Temperatures and relative humidities were recorded and the actual air movements were studied by using smoke trails. The investigations were made under a variety of weather conditions and with a wide range of outlet and inlet areas.2. It was shown that the atmospheric conditions in the large byre were almost always superior to those in the small byre, and this was undoubtedly due to the greater cubic space per cow in the large byre. Adequate ventilation was, however, readily attained in the small byre provided the outlet area was sufficiently large.

Beschreibung: SUMMARYWhen maize forms a large part of the diet of any group of people, pellagra can be prevented by increasing the amount of nicotinic acid or by increasing the amount of tryptophane in the diet. The possibility of increasing the nicotinic acid content of maize by genetical means presents a promising field.

Beschreibung: SUMMARY1. The weights of muscular tissue, fatty tissue, bone, and tendons, etc. in the carcasses of twenty-nine cattle, fifty-five sheep and forty pigs are given. The weights of fat, dry fat-free residue, and water in the muscular and fatty tissues from the carcasses of twenty-nine cattle, twenty-nine sheep and two pigs (one wild and one domesticated) are also given. The cattle represent eight breeds, the sheep nine breeds and the pigs two breeds. Ages range from newly born to over 12 years and there are fifty females, seventy castrated males and four newly born males. The animals thus represent a very wide cross-section of the meat industry.

Beschreibung: SUMMARYIn presenting the results of these investigations, we have attempted to discuss in each section the findings that have been described, and here we will merely be concerned with summarizing the major points that have emerged.

Beschreibung: SUMMARYCertain vegetable seeds show such a marked loss of viability on storage that they are generally useless after 1–2 years storage under average commercial conditions; the most valuable seeds which store particularly badly are parsnip, onion and carrot. Storage experiments were therefore designed and set up to show the effect of the following factors on the viability of the seeds:(a) The water content as determined by the humidity of the atmosphere in which the seeds were stored.(b) Atmospheric conditions, viz. ventilated air, unventilated air and nitrogen.(c) Temperature.

Beschreibung: SUMMARYIt has been shown in a previous communication that the meal-replacement value of young grass in actual pig-feeding practice is considerably poorer than would be anticipated from a consideration of its content of ‘total digestible nutrients’ as determined by means of pig digestion trials. This is because the figure for ‘total digestible nutrients’ takes no account of the energy expended by the pig in consuming and masticating its food. Although this wastage of energy does not represent a serious loss in relation to the rate of live-weight increase in the case of ordinary pig meals fed in the form of a thick slop, it becomes of considerable significance when grass forms a major component of the diet, on account of the bulkiness of the grass and its unfavourable physical texture from the standpoint of consumption by pigs.

Beschreibung: SUMMARY1. Some data are given for the relative buffer-index values of saps from underground parts of wheat, barley, oats, potatoes and turnips.2. The correlation of these values with limits of tolerances of soil-pHranges by the plants is discussed.3. Some possible practical applications for these data are indicated.

Beschreibung: SUMMARY1. In a ration containing paddy straw, the large amount of oxalate ingested does not act in the same way in the ruminant system as has been observed when oxalate-rich spinach is fed to rats. About 10 % of the ingested oxalic acid is recovered in the faeces, and this can be explained as arising out of pre-formed insoluble and unabsorbable calcium oxalate present in paddy straw; the remaining 90%, which is soluble potassium oxalate, does not react with the calcium of the Tation to form unabsorbable calcium oxalate.

Beschreibung: SUMMARY1. The effect of iodinated casein feeding on the respiratory metabolism of the female sheep has been studied, using a spirometer technique with direct analysis of expired air.2. The effect of iodinated casein on basal metabolism was linearly related to the dosage expressed in mg./kg. W0·73. The effect on pulse rate was not linear: there was a greater acceleration at the higher levels.

Beschreibung: SUMMARY1. The compositions and digestibilities of ten selected typical Northern Irish meadow hays have been ascertained and compared with similar data published by other workers for meadow hays produced in the British Isles.2. It is suggested that average Northern Irish meadow hay of reasonably good quality has a starch equivalent value in the region of 35 on a drymatter basis. Poor samples will have a value in the region of 25.

Beschreibung: With the installation of more factories for the decortication of cotton-seeds in Pakistan, the utilization of cotton-seed hulls as a feed is likely to assume great importance. During 1949–50, the writers made determinations of the chemical composition and the feeding value of Pakistan cottonseed hulls by conducting a digestibility trial on dry Sahiwal cows. They are found to contain 39.89–56.47% total digestible nutrients (mean value = 48.68%) and 0.0–0.38% digestible protein. It was observed during the trials that the cows could eat about 20 lb. of hulls per head per day without difficulty. The cows also ate hulls in preference to wheat straw.Being low in calcium and phosphorus, cotton-seed hulls should not be used as a sole roughage for long periods, unless supplemented with calcium or phosphorus in mineral form, or preferably with silage, legume hay or green fodder of good quality.Pakistan cotton-seed hulls appear to be equal, if not better, than wheat straw as a cattle feed. From the economic point of view, hulls should be used as a cattle feed only if they are purchasable at about the same price as wheat straw.

Beschreibung: 1. The relation between the soluble-nitrogen content of grass silage and the pepsin digestibility has been investigated, and formulae have been derived for calculating the protein digestibility in the silage dry matter from the determined solublenitrogen content.2. Comparisons have been made between the calculated results for protein digestibility, the results using the formulae of Watson and Dijkstra and the digestibility as determined on sheep.3. The peculiarities of molassed silage in the above connexion have been noted.

Beschreibung: Designs are given for factorial experiments with three, four or five factors at two levels each, using thirty-two plots in a 4 × 8 lay-out on the ground. The effects of both rows and columns can be eliminated from the estimate of error. Provided that three-factor interactions can be ignored, information can be retained on all two-factor interactions.

Beschreibung: The influence of growing plants on nitrification in the soil was studied by means of small lysimeters of which four were planted to a perennial grass, four to an annual millet crop and four were left fallow.Nitrification was entirely repressed under the grass from the second season after its establishment onwards, and did not take place even when the grass was dormant in winter. This was due to a direct influence of the living root, since in the fallow soil which was treated similarly, nitrification took place freely throughout the winter. Under the annual crop a repression of nitrification could be detected only towards maturity of the crop and the soil solution was completely depleted of nitrates at this period. Nitrification was resumed, however, immediately after the crop was ripe and had died off and continued through the winter.During the period that nitrification was depressed replaceable ammonia made its appearance in the soil in more than normal quantities. This fact is hold to indicate that the plant exerts its influence on the mineralization of nitrogen in the soil by paralysing the autotrophic dehydrogenase system of the nitrifying organisms without interfering with the process of ammonification and not, as has been claimed, by excreting such quantities of carbonaceous matter that nitrates are reassimilated by micro-organisms.By virtue of the constancy of the carbon-nitrogen ratio in soils this influence of plants on the mineralization of nitrogen has a very important bearing on the conservation of soil humus and consequently on any system of alternate husbandry. Some of its implications were discussed with particular reference to local fertilizer practice and field experience.

Beschreibung: For three consecutive years American hybrid maize was grown, under replicated experimental conditions, in the south of England. Each season, the influence of the spacing of the plants and the use of nitrogenous fertilizer on the yield and composition of the crop and of its separate portions of leaf, stem and cob was investigated.The growth of the maize, and especially its yield of dry matter, were influenced by the weather conditions during the season. The weight of fresh crop varied, with season and treatment, from 126 to 278 (averaging 209), and of dry matter from 20 to 70 (averaging 50) cwt./acre.Thinning below the established plant populations of up to 30,000 plants per acre regularly reduced these yields. Top-dressing with sulphate of ammonia increased them in 1947 and 1949, but decreased them in 1948.The yield of crude protein varied from 2.2 to 5.0, and of soluble carbohydrates from 12 to 46 cwt./acre. The top-dressing increased the protein content of all portions of the plant.The cob contributed, on a weight basis, 46% of the fresh crop, 49% of its dry matter, 54% of its crude protein and 54% of its soluble carbohydrates. Details are given of the chemical composition of the whole plant, and of its separate leaf, cob and stem, for each season and treatment.A later paper will deal with the making of silage from the maize crops and with the yield, composition and nutritive value of the silage.

Beschreibung: Mating Wessex Saddleback with Gloucester Old Spot pigs shows clearly that the former are of the three genotypes expected if the belt pattern is primarily determined by a single dominant gene (Be). Breeding tests and measurements of belt width agree in showing that homozygotes tend to have medium to wide belts, heterozygotes tend to have medium, narrow or broken belts, while pigs homozygous for the recessive are black. Crosses of Wessex with black-spotted pigs produce black piglings with or without wide symmetrical belts depending on the genotype of the Wessex parents.Selection of breeding pigs with narrow belts maintains a high incidence of recessive blacks. Solid blacks which are nevertheless genetically belted may occur, but if so their numbers are likely to be very small.Evidence is given which suggests that pigmentation in the skin and hair of Wessex × Large White pigs is much reduced if the Large White parents have blue eyes.

Beschreibung: 1. A statistical study of factors affecting variation in persistency of lactation has been made using 5000 lactation records from twelve leading herds of Ayrshire cattle in south-west Scotland for the period 1930–9.2. It is suggested that a satisfactory numerical expression for the shape of the lactation curve could be obtained from the formula, Persistency = where A is the milk yield during the first 180 days and B is the initial milk yield, namely, the milk yield during the first ten weeks of lactation.3. The interrelationships of persistency, initial milk yield and 180-day milk yield showed that these three characteristics are positively correlated with one another on a between cows within herd basis. This meant that it should be possible to combine high initial milk yield with high persistency to obtain increased total production.4. The effect of month of calving on persistency of lactation varied significantly between herds. On the average, the highest persistency was attained by cows calving in the winter, and the lowest by summer calvers.5. The variation of persistency with age showed that it is necessary to correct for the high persistency of first calvers when comparing cows with different lactations.6. The average repeatability of persistency was 0.242 in the present material, while heritability was of the order of 0.10–0.15.7. It has been concluded that improved feeding and management would bring about the greatest returns in the direction of improved persistency.

Beschreibung: 1. Differences in cattle population (4 June returns) and in average body size of fat cattle (data from the collecting centres) have been illustrated for the three counties (Cardiganshire, Carmarthenshire and Pembrokeshire) constituting this region. They indicate the superiority of Pembrokeshire.2. The six westerly collecting areas of Pembrokeshire produce the heaviest cattle of better grading. It has a higher proportion of steers to heifers than the rest of the region.3. The statistical analysis of the data has made it possible to partition the region into four main groups of centres, which show significant differences in the size of the fat cattle.4. The superiority of group 1 has been demonstrated in relation to (a) the seasonally of deliveries, (b) the percentage grading and (c) in the average live weights.5. These differences are examined in greater detail by comparisons of the deliveries to the Pembroke and to the Llandilo centres. These show that Pembroke is superior in average live weights, percentage grading and in the proportion of steers to heifers.6. The ungraded cattle are also examined, and the results indicate the same trends within the region as for the graded cattle.7. The possible explanation of the variations or the ecology of beef production has been discussed in the light of Ashton's (1930) suggestions that variations in body size between cattle of different breeds is mainly due to the calcium and phosphorus content of the soil.8. The conclusion is drawn that differences of climate dominate the whole picture, because of the effect of rainfall on leaching and soil erosion, as well as on the quality of the harvested fodders, the effect of temperature on the length of the growing season and of the beneficial influence of sunshine on the quality of both grass and hay.

Beschreibung: A study has been made of the bias in error which occurs when Latin-square change-over trials conducted on dairy cattle are analysed by the usual method for Latin-square experiments, with modification for carry-over effects. Bias is present for adjusted direct effects and for permanent effects (direct plus carry-over), but does not exist for unadjusted direct effects.Analyses of fifteen sets of experimental data showed that the bias is of no importance in 3 × 3 designs but might be serious for some practical situations in the 4 × 4 designs. A tentative factor to correct for bias was given for the latter case.

Beschreibung: 1. The structure of the cattle population (4 June returns), as well as of cattle sales to the Ministry of Food, have been illustrated.2. The trends in cattle production show the definite changes from that of the traditional storestock rearing to that of milk selling.3. A considerable part (38·2%) of the total graded animals slaughtered for beef are the ‘wastage’ animals from the breeding and dairying herds.4. Reference has also been made to the high proportion of ungraded cows (36·7% of the total cows) purchased by the Ministry. The ungraded cattle, however, are only 17% of the total sales. On the other hand, the ungraded ‘wastage’ cattle contribute 90% of the total ungraded cattle.5. More heifers than steers were sold for slaughter, and it has been shown that the average live weight of the graded steers is nearly 224 lb. heavier than that of the heifers.

Beschreibung: Between 1941 and 1946 some twenty-five field experiments were carried out at various centres in England to assess the factors which determine the yield level and seed composition of linseed (oil flax). The experiments were of multifactorial design, and the main variables studied were varietal differences, levels of mineral nutrient supply and plant population. Additions of nitrogen (35 lb./acre) over all experiments raised the yield of seed by 10%, whereas additional phosphorus (50 lb. P2O5/acre) or potassium (80 lb. K2O/acre) had small and inconsistent effects. A significant interaction between nitrogen and variety was recorded in one trial, but in twelve out of fourteen experiments the varieties reacted uniformly to a combined application of nitrogen, phosphorus and potassium, while in the remaining two experiments the interactions were contradictory.

Beschreibung: 1. The experiment previously described (series 4, Holmes, 1949) on the effect of massive applications of nitrogenous fertilizers on the productivity of a ryegrass dominant pasture was continued for 3 years (1946, 1947, 1948). The manurial treatments ranged from none to the application of 312 lb. nitrogen per acre and this was applied with and without 135 lb. P2O5 and 168 lb. K2O per acre. Farmyard manure was applied to one block in 1948.2. With the heaviest nitrogen treatment plus phosphate and potash the average yield for 3 years was 8000 lb. dry matter and 1640 lb. crude protein (similar to the yield in 1946) compared with a control yield of 4720 lb. dry matter and 590 lb. crude protein. The yields declined from year to year when phosphate and potash were not applied, the decline being greatest with the heaviest application of nitrogen.3. The seasonal distribution of the yield of herbage was very considerably modified by the time when fertilizers were applied.4. The botanical composition of the swards was related to the yield, 70% of the grasses in the highest yielding sward being perennial ryegrass and cocksfoot while the lowest yielding sward contained only 35% of these grasses.5. The manurial treatments had no effect on the pH, loss on ignition or the content of readily soluble P2O5 in the soil, but in the first year there was some evidence of a general reduction of readily soluble K2O to a low level.

Beschreibung: 1. Studies were made of the effects of varying ground water-levels upon the productivity and composition of Italian Ryegrass grown on a calcareous light peat in the Fenland area. Six cuts were taken throughout the season at 3 to 4-weekly intervals.2. High ground water-level (approximately 15in. below ground surface) had a very deleterious effect on the total yield of fresh grass and of dry matter. Yields were little more than half of those obtained at medium and low water-levels (24 and 38 in. below ground surface, respectively).3. High water-level apparently interfered with nitrogen metabolism in the soil, and considerably lower percentages of crude protein were found in the grass growing on the high water-level plots than at the other levels. On the other hand, the percentage of crude fibre remained fairly constant for all levels of ground water.4. High water-level also had a depressing effect on the percentage of potassium, magnesium and chlorine in the grass. It had no obvious effect upon the calcium and phosphorus levels in the plants. The silica content of the grass rose steadily as the season advanced, this being most marked on the high water-level plots.5. Physical examination of typical plants showed the effect of the various ground water-levels upon the development of the root systems, with consequent effect upon the chemical composition of the grass.6. The composition of hay and aftermath showed similar changes to those reported for the green herbage.7. The findings are discussed in relation to grassdrying policies in Fenland areas.

Beschreibung: 1. Eight Cheviot ewes, bearing twins, housed in individual pens, and given the choice of a protein concentrate, a carbohydrate concentrate, hay, minerals and water, failed to select a ration that allowed them to bear and rear strong healthy lambs.2. Three ewes maintained under these conditions developed a condition resembling pregnancy toxaemia.3. The amount of food eaten by each ewe decreased during the last few weeks of pregnancy, This is probably the reason for the disappointing performance of the ewes at lambing.4. The possible influence on the behaviour of the ewes of the constant presence of food is discussed.

Beschreibung: The digestibility of carotene in dried grass was measured by the Cr2O3 method in both cows and goats. In the goats the direct method was simultaneously used for comparison with the Cr2O3 method.The main conclusions were:1. When mixed with the concentrate portion of the ration of lactating goats, Cr2O3 was recovered in the faeces in four experiments in amounts equal to 100·0, 99·1, 99·1 and 96·0% of the amount ingested.2. The apparent digestibility of carotene in the goat was measured both directly by the use of metabolism crates and indirectly by using Cr2O3 as an indicator of equivalence of faeces and food. By the former method digestibilities of carotene in four goats were 68·7, 62·7, 61·8 and 59·6%. The corresponding digestibilities obtained from the same faeces samples by the Cr2O3 method were 67·4, 62·9, 61·8 and 58·9%.3. In six cows, on the diet similar to that of the goats, the Cr2O3 method showed that 59·3, 54·0, 54·4, 54·4, 57·1 and 55·5% of carotene was apparently digested.4. Reasons for preferring the use of added Cr2O3 to natural constituents of the food as a marker are discussed.5. The individual results from cows and goats have been statistically analysed to partition the various sources of variance, and it has been shown that fewer animals for a longer time give a more reliable result than more animals for a shorter time.

Beschreibung: 1. Trials made near Cambridge in 1949 and 1950, under ‘mild’ and ‘hard’ spring weather conditions respectively, have confirmed that the findings of Aberg & Denward in Sweden, and of Pedersen, Andersen & Hermansen in Denmark, concerning distortions in barley caused by MCPA and 2,4-D, are also valid under English conditions.2. Damage to barley caused by the application of MCPA and 2,4-D up to the 2-leaf and early 3-leaf stages may be recognized by the occurrence of many tubular leaves and bowed or trapped ears. As little as 2 lb./acre of 2,4-D, as the amine salt, applied at this stage may also cause severe stunting of theplants with distortion of the roots.3. Damage to barley by the application of MCPA and 2,4-D at the 3–4-leaf stages may be recognized by the occurrence of tweaked ears. The application of as little as 2 lb./acre of MCPA, as the sodium salt, at these stages may cause tweaking in over 50% of the ears. 2,4-D (as amine) at the same dosage causes more distortion. Although the reduction in yield due to such tweaking may be slight, the grain sample is irregular in size, with a number of naked grains, and malting quality may be reduced.

Beschreibung: 1. Two groups, each of six Ayrshire dairy cows, have been watched in the field for a total of twentytwo 24 hr. periods during the months May to September. No supplementary foods were fed at any time. One group grazed under a system of close-folding and the other in small rotational paddocks.2. The effect of the different systems of management was small. It was clear, however, that closefolding increased the time spent in grazing and decreased the weight of herbage eaten. The milk yields from both groups were very similar.3. A very constant pattern of behaviour over the 24 hr. period, similar for both groups, was observed. The most prolonged grazing period always occurred immediately after the cows returned from evening milking.4. The amount of grazing during the hours of darkness was small at all times of the season but tended to increase as the evenings shortened and the nights lengthened. The cessation of evening grazing was closely linked with the fall of darkness at all times of the year.5. The activities during the ‘day’ period were less regular but, nevertheless, showed a marked division into three main spells of grazing, of which one occurred immediately after morning milking, separated by two main spells of rest.6. Stage of lactation, individual milk yield and live weight appeared to have no direct relation to the amount of time spent in grazing. Cows watched in both 1949 and 1950 grazed for very similar times despite differences in their stage of lactation.7. Increasing defoliation of the paddock resulted in an increased grazing time by the rotationally grazed cows.8. Close-folded cows grazed for a shorter time on herbage of low moisture content than on herbage of high moisture content, whilst eating virtually the same weight of dry matter.9. Climatic changes to the extent met with in south-west Scotland had only a limited effect on the general pattern of grazing.10. The physiological activities of dunging, urinating and drinking showed only small day to day variations.11. The distance walked during grazing in the 24 hr. by one individual cow from each group showed only a slightly longer track for the rotationally grazed animal, the average distance being about 2000 yards.

Beschreibung: Ten experiments on sugar beet in 1949 tested a phosphate-potash fertilizer applied in different ways. There was no damage to germination or plant establishment by fertilizer placed in bands 2 in. to the side and 2 in. below the level of the seed.There were no significant differences between the yields of sugar given by placed and broadcast fertilizer. Similar yields were given by broadcast applications applied early and worked deeply into the seed-bed and by dressings on the seed-bed which were worked in shallowly. Split dressings where half the fertilizer was broadcast and half was drilled beside the seed were not markedly superior to placing or broadcasting all the fertilizer. In most of the experiments placing gave more vigorous growth than broadcasting the fertilizer during late spring and early summer; at harvest this superiority had vanished.The results of these experiments confirm those carried out in 1947 and 1948. There is no advantage from placing the full dressing of fertilizer beside the seed in districts where the crop is normally grown, except that labour is saved in applying the fertilizer.

Beschreibung: The importance of conducting studies on the behaviour of grazing animals has been stressed by several authors. Stapledon & Jones (1927) indicated the need for such work; while more recently Stapledon (1948, 1949) has made further reference to this need.Adequate reviews of the work conducted prior to 1939 are to be found elsewhere (Castle, Foot & Halley, 1950; Tribe, 1950), and only the more important aspects need be considered here. The main weakness on the part of many of these earlier studies was that they were based on few observation periods, and that few animals were observed during each period. Many workers (Cory, 1927; Hodgson, 1933; Sheppard, 1921) carried out their observations during the daytime only, on the assumption that little or no grazing occurred after dark. In spite of this and the fact that the methods of study adopted varied considerably, some correlation exists between the results reported by the different workers.

Beschreibung: 1. Chicks from commercial sources were housed intensively and fed on a series of rations containing decorticated extracted groundnut meal as the main supplementary source of protein, with and without additions of animal by-products and aureomycin. Parallel groups received rations conforming to Government regulations in their content of sources of animal protein.2. Growth and feed efficiency up to point of lay were as good in groups fed on all-vegetable rations, containing 18% of crude protein in the starting ration and 16% in the growing ration, as in groups fed on regulation rations of the same protein content.3. Performance on the all-vegetable ration up to 6 weeks of age was not as good as on the regulation ration. This inferiority could be largely or wholly corrected by adding extra groundnut meal and condensed fish solubles to the ration. Growth and feed efficiency over the whole rearing period were not improved by the addition of these supplements.4. Addition of aureomycin stimulated growth over the whole rearing period but failed to improve feed efficiency.5. Protein levels in the ration, the provision of animal protein factor(s) and aureomycin were without effect on the age at which laying began.6. Current estimates of the chick's requirement for certain amino-acids appeared to be too high when this type of ration was used.7. The addition of riboflavin to these starting rations was essential. When this was done mortality was low, leg weakness absent and feathering rate normal.

Beschreibung: Between 1942 and 1950, some thirty field experiments have been carried out in the southern half of England to assess the potential value, either for grain or forage production, of seventeen openpollinated flint or dent maizes together with twentynine single or double hybrids of American or Canadian origin.Early-maturing flint varieties will consistently ripen grain, but before mechanical threshing or storage, the cobs require drying. Sibthorp, a mass selection made from an unknown German variety, is the earliest and most productive flint maize so far tested, and in the experiments has yielded as much as 39 cwt. of grain per acre with an average of 24 cwt. The earliest American hybrids, i.e. those with a U.S.A. rating of 80 days from sowing to maturity, give very high yields of grain in favourable seasons. Within the group Wisconsin 240–275, a yield level equal to or exceeding 50 cwt./acre has on occasion been recorded. On the other hand, in the most unfavourable years, such hybrids just failed to produce ripe cobs.Attempts to maintain sixty-five parent inlines of the earliest hybrids have largely failed. However, many of the parent single crosses have matured, and the production on a field scale of the double-cross seed of both Wisconsin 240 and 255 has been carried out.Spacing experiments indicate that for optimum grain production a density of 6 plants/sq.yd. is required for both flint varieties and the earliest hybrids. A spatial arrangement of individual plants is to be preferred to that of groups or hills.American hybrids, in the class of ‘90 days’ to maturity, will in all but the most unfavourable seasons reach the ‘early-dent’ stage of the grain before the incidence of autumn frosts. Yields of dry matter of plants harvested in this phase have ranged from 30 to 85 cwt. of dry matter per acre. In these trials, the plant density was standardized at 4 plants/sq.yd. and higher densities may be demanded for optimal yields.The ratio of the ‘ear’ (that is, the cob, immature grain and enclosing leaf sheaths) to the total shoot weight at harvest varies greatly with the variety or hybrid. With White Horsetooth, the usual variety grown for fodder in England, no cobs are formed before the plants are killed by frost, while with the early hybrids, the ear may be half the weight of the whole shoot.The earliest variety Sibthorp from an early May sowing takes approximately 70–80 days to reach full anthesis, while ‘80-day’ American hybrids are a week later. From sowing to full maturity the period in England is from 140 to 160 days, thus compared to conditions in Minnesota the period is nearly twice as long. Because of the much slower rate of development and because of the humidity of English autumns, it is concluded that until the date of maturity can be advanced some 14 days, grain production on a field scale is not yet feasible. On the other hand, many of the American hybrids are well fitted to the production of silage. The greatest drawback to the introduction of such hybrids is the liability of the seed and seedlings to be attacked by rooks.

Beschreibung: In dealing with fertility in sheep there are a number of initial difficulties. On the one hand, there is generally a lack of any uniform definition of such terms as ‘fertility’, ‘fecundity’ and ‘prolificacy’ (cf. Marshall & Hammond, 1947; Lush, 1938; Rice, 1942; Asdell, 1946; and others); on the other hand, investigators have been confronted with a real difficulty in procuring suitable information which would conform to the requirements of any single and adequate definition of fertility. Because of this, fertility figures have been calculated in different ways* and may differ by as much as 30%. The situation is at present so confused that reference to similar work, especially when the original papers are not available, or the terms not clearly denned, is often of dubious value if not altogether misleading. In the past the data analysed were mostly based on farmers' answers to questionnaires or on flock records. The limitations of such methods are only too obvious; yet it must be clearly realized that in commercial flocks there is no possibility of any basic departure from them, even though their accuracy could in many cases be improved. In other words, only such information is collected as the circumstances allow. This, for instance, may be the number of lambs docked per ewes put to ram in one flock and number of lambs docked per ewes lambed in another.

Beschreibung: 1. A small-scale plot experiment was carried out from 1947 till 1949 to study the effect of massive dressings of nitrogen with and without phosphate and potash on the yield of a ryegrass-dominant sward. A 4 × 4 Graeco-Latin square was used.The nitrogen treatments were: (1) no nitrogenous fertilizer, (2) 260 lb., (3) 520 lb., (4) 416 lb. nitrogen per acre per annum. These applications were divided into four or five equal dressings, the first being applied in March and the others after successive cuts.In 1948 and 1949 the following mineral treatments were also applied: (A) no mineral fertilizer, (B) 180 lb. K2O per acre, (C) 120 lb. P2O5 per acre, and (D) treatments B and C combined. These treatments were applied in two parts, half in spring and half in midsummer.2. Applications of phosphate did not affect the yields of herbage but yields were severely restricted in the absence of potash.3. Where potash was applied there was no significant change in the annual yield of herbage from 1947 to 1949 for any one of the treatments. The nitrogen treatments increased the yields from 4300 lb. dry matter and 600 lb. crude protein per acre with treatment 1 to 9000 lb. dry matter and 1900 lb. crude protein with treatment 3. The yield response of dry matter to nitrogen applications was curvilinear, but that for crude protein was rectilinear.4. Increasing the application of nitrogen per cut from 52 to 104 lb. per acre raised the protein content in the dry matter of the herbage from 15·20 to 18·25%.5. The plots receiving the nitrogen treatments gave earlier production and also produced a greater proportion of the total yield in July-September than the untreated control plots.6. Where potash was present the average net efficiency of recovery of nitrogen for 3 years was 47, 39 and 37% for treatments 2, 3 and 4 respectively.7. Where potash was present the content of vigorous grasses in the sward (perennial ryegrass and timothy) was increased in relation to the quantity of nitrogen applied, from approximately 40% in treatment 1 to 75% in treatment 3. The content of vigorous grasses in the sward was reduced in the absence of potash.8. The results and their practical implications are discussed.

Beschreibung: 1. The methods of investigation of the effect of ground water-level on crop growth, together with tho field installations in use, are discussed.2. Direct field experiments are handicapped by the difficulties of achieving close control on a sufficiently large scale, due to considerable variations of surface level and depth of peat within individual fields and to rapid fluctuations in rainfall and evaporation. Many recorded experiments are associated with climatic conditions of substantial precipitation during the growing season.3. Seasonal fluctuations of ground water-level in Fen peat soils in England, in natural and agricultural conditions, are described.4. The local soil conditions are outlined and the implications of profile variations are discussed.5. The effective control of ground water-level on a field scale requires deep and commodious ditches and frequent large underdrains to ensure the movement of water underground with sufficient freedom to give rapid compensatory adjustment for marked disturbances of ground water-level following the incidence of heavy rain or excessive evaporation.6. A working installation for a field experiment in ordinary farming conditions is described and the measure of control attained is indicated.

Beschreibung: In the carrying out of comparative determinations of the supplemental values in pig feeding of the proteins in different protein concentrates, the writers consider the following conditions to be fundamental, and must be observed if reliable results are to be obtained:(1) The comparison must be conducted over the period from weaning to about 90 lb. live weight. Measurements made in the later stages of growth can have no meaning, since supplementation of the basal mixture (cereal plus middlings or fine bran) with the protein-rich concentrates under comparison has no significant effect at tins stage on the rate of growth or nitrogen retention. Examples of the misleading results that are obtained by prolonging the period of comparison to 150 or 200 lb. live weight, instead of terminating the trial before the attainment of 90 lb. live weight, were encountered during the course of the present investigation, and are cited in the text.(2) The diets to be compared must be so designed as to contain, as nearly as possible, equal percentages of ‘total digestible nutrients’, as based on computations from digestion coefficients derived from digestion trials with pigs.(3) The daily allowances of meal must be scaled to live weight, and the diet must be sufficiently palatable to ensure clean food consumption.(4) The diets must make adequate provision for the mineral and vitamin requirements of young growing pigs.(5) The comparison in the case of growth experiments must be made by the method of individual feeding, and in accordance with the requirements of the modern statistical lay-out, so that the records of live-weight gain and food consumption may be submitted to statistical analysis.(6) The diet forming the standard for comparison should contain the minimum amount of protein needed for the maximum rate of growth compatible with the available supply of net energy. In the case of white-fish meal, which was the standard protein supplement in the present comparisons, this condition has been found in earlier work to be realized when a diet composed substantially of barley meal and middlings contains 7% of this animal-protein food.(7) In the initial tests, the experimental diet should contain, as nearly as possible, the same percentage of digestible crude protein as the standard diet, and the percentage of the protein supplement under test should be such as to provide as much digestible crude protein as is contained in the 7% of white-fish meal in the standard diet. Under such conditions of feeding, differences of protein quality in the two feeding treatments will be the factor responsible for any observed differences in the rate of live-weight increase or of nitrogen retention.Should the pigs on the experimental treatment display a poorer rate of growth, or of nitrogen retention, than those on the standard treatment, then further trials should be undertaken in which the percentage of protein supplement under test is progressively increased, whilst still maintaining equality between the experimental and standard diets in respect of ‘total digestible nutrients’, until a level is reached at which the experimental pigs show a rate of live-weight increase, or of nitrogen retention, equal to that of the pigs on the standard treatment. The final stage of the comparison, therefore, is based on the results of feeding tests in which the maximum possible rate of growth, or of nitrogen retention, is obtained, both on the standard and experimental treatments, with diets supplying, respectively, the minimum amounts of the two types of protein supply.The object of the present investigation has been to compare the supplemental values of a typical animal-protein concentrate (white-fish meal) and vegetable-protein concentrate (ex. dec. ground-nut meal). The aim has been to determine what percentage of ex. dec. ground-nut meal must be incorporated with a basal diet, composed approximately of 2 parts by weight of barley meal, 1 part of middlings (or fine bran) and a small allowance of lucerne meal and minerals, to promote the same rate of growth, or of nitrogen retention, in young pigs as is obtained with a standard diet containing roughly the same proportions of the basal foods in conjunction with 7% white-fish meal, the diets under comparison being made up so as to contain equal percentages of ‘total digestible nutrients’.On the basis of pig digestion trials, 8 parts by weight of ex. dec. ground-nut meal contains as much digestible crude protein as 7 parts of whitefish meal. The diets under comparison in the initial growth and balance trials were made up, therefore, to contain, respectively, 7% of white-fish meal and 8% of ex. dec. ground-nut meal. Their contents of crude protein, digestible crude protein and ‘total digestible nutrients’ were approximately equal. Over a range of live weight from 36 to 90 lb., the pigs receiving the white-fish meal averaged 0·92 lb. of live-weight increase per day, with a mean efficiency of food conversion of 3·08 lb. per lb. of live-weight gain. The corresponding figures for the pigs receiving the ex. dec. ground-nut meal were 0·73 and 3·87 lb. These differences were strongly significant and pointed clearly to the poorer supplementa. value of the vegetable protein supplement. Confirmation of this finding was given by the results of nitrogen-balance trials on young pigs. At all stages, pig (1) receiving the standard diet containing 7% of white-fish meal was retaining nitrogen at a distinctly higher rate than pig (2) subsisting on the diet containing 8% of ex. dec. ground-nut meal. Over the 43 days of continuous measurement, pig (1) consumed 1719·5 g. of nitrogen, and retained 720·5 g., or 41·9% of the total nitrogen intake; whereas pig (2), which had steadily fallen behind in live weight during this period, consumed a total of 1591·9 g. of nitrogen, and retained 566·6 g., or only 35·6% of the ingested nitrogen. It was clear from the results that the protein assimilated from the diet containing ground-nut meal is not so suitably balanced in respect of amino-acids as the digestible protein in the standard diet, and is subject on this account to a higher degree of de-amination, with a correspondingly greater wastage in terms of urinary nitrogen.This conclusion was substantiated by re-calculating the results for the same range of live weight, namely, 62·92 lb., a range which falls within the limits that have been shown to be necessary for a sensitive comparison. For this live-weight gain, pig (1), receiving white-fish meal, required 22 days, over which period the total consumption of nitrogen amounted to 771·5 g., of which 327·6 g., representing 42·5% of the ingested nitrogen, was retained, and 226·9 g. (29·4% of the nitrogen intake) eliminated in the urine. The corresponding results for pig (2) receiving groundnut meal were distinctly inferior. The time needed for the same gain in live weight averaged 25·3 days; the necessary nitrogen consumption amounted to 859·3g., and of this, 301·8g.(35·1% of the intake) was voided in the urine and 309·5 g. (36·0%) was retained in the body of the animal.A succession of growth trials was next carried out in which the effect of increasing the level of ex. dec. ground-nut meal to 12, 14, 15, 16, 17 and 20%on the rate of live-weight increase between weaning and 90 lb. live weight was investigated. Although the successive increases led to progressive improvement of the results in relation to those obtained on the standard diet containing 7% of white-fish meal, was not until the 20% level of feeding was reached that the diet containing ex. dec. ground-nut meal gave as good results in respect of rate of growth and efficiency of food conversion as were obtained by the use of the standard diet.The same result was obtained in the investigation of the problem from the standpoint of nitrogen retention, the inclusion in the experimental diet of as much as 20% of ex. dec. ground-nut meal being found necessary to so rectify the ill-balance of the amino-acids in the cereal part of the diet as to make possible, between weaning and 90 lb. live weight, the maximum rate of nitrogen retention such as was obtained in the case of the pigs receiving the control diet containing 7% of white-fish meal.In view of the variation from consignment to consignment of the protein content of such proteinrich concentrates as white-fish meal and ex. dec. ground-nut meal, it is necessary to define the different diets under test in terms of their protein content rather than their content of protein supplement. Examined from this standpoint, the results of the growth trial and the balance trial, in which ex. dec. ground-nut meal formed 20% of the diet under test, showed a substantial measure of agreement. Averaging the results of these trials, it is found that the standard diet supplying 7% of white-fish meal contained 14·2% of crude protein on the air-dry basis (16·4% on the basis of dry matter), and of this, 32%, or roughly one-third, came from the white-fish meal. In the case of the diet supplying 20% of ex. dec. ground-nut meal, the crude protein content on the air-dry basis rose to 18·5% (21·2% on the basis of dry matter), and as much as 54%, or rather more than half, of the total protein was derived from the vegetable-protein supplement. The two diets contained, respectively, 11·6 and 15·6% of digestible crude protein, and of ‘total digestible nutrients’, 62·4 and 62·7% respectively (air-dry basis). On the two diets as so made up, equality in respect of rate of growth and nitrogen retention in young pigs was made possible, only, however, at the expense of a less efficient and more wasteful utilization, as evidenced by the greater degree of de-amination and a correspondingly higher loss of nitrogen in the urine, of the protein in the ration containing ex. dec. ground-nut meal.The feeding of as much as 20% of ex. dec. groundnut meal in the rations of young bacon pigs for the purpose of ensuring the maximum rate of growth compatible with the available supply of net energy may seem an extravagant usage of the protein concentrate, but this is really not so if it is kept in mind that, in accordance with the writers’ earlier findings, the protein supplement may be omitted altogether at about 90 lb. live weight without occasioning any depression of the rate of live-weight gain or the efficiency of food conversion. Thus, in the growth trial in which the diet containing 20% of ground-nut meal was compared against the standard diet, no more than 35·5 lb. of the vegetable-protein concentrate was required, on an average per pig, between the live weights of 36 and 90 lb., and following the attainment of 90 lb., the use of the ground-nut meal could, if desired, have been discontinued.Perhaps the best way of economizing in the use of ground-nut meal, however, is to feed it in conjunction with a small allowance of an animal-protein food, such as white-fish meal. In growth trial no. 4, for example, the diet containing 6% of ex. dec. groundnut meal and 2% of white-fish meal gave as good results as the diet containing 15% of ex. dec. ground-nut meal. Thus, the introduction of as little as 2% of white-fish meal into the diet enabled the percentage of ground-nut meal to be reduced from 15 to 6%, with a consequential reduction of the total digestible crude protein from 13·9 to 11·2%, without affecting the rate of live weight gain or the efficiency of food conversion.

Beschreibung: In the course of two breeding seasons 137 mature to aged ewes of mixed breeds but predominantly Border Leicester × Cheviots, Dorset × Cheviots, Suffolks and Hampshires and their crosses, have been injected with PMS or PU, and at different levels of dosage, and slaughtered at intervals after service to determine the sequence of events following treatment. In addition ten ewe lambs received similar treatment and eighty-one flock Suffolk and Romney Marsh ewes, of which forty-nine were injected, have been studied. The results may be summarized as follows:1. The injection of 500–2000 i.u. PMS on the 12th day of the oestrous cycle will regularly induce multiple ovulations at the ensuing heat.2. There is a significant dose-response relationship between 500 and 2000 i.u. PMS. Mean ovulation rates observed were: 500 i.u., 4·1; 1000 i.u., 10·6; 2000 i.u., 15·8. There is, however, considerable variation, the ranges being 2–9, 4–33 and 8–29 respectively.3. The injection of 1000 i.u. PU subcutaneously on the 12th day of the cycle causes marked ovarian and cyclic abnormalities, and heat may be entirely suppressed. When injected intravenously at heat following a priming injection with PMS on the 12th day there is no evidence that it increases the rate of ovulation; in other words, the ewe can ovulate up to at least thirty ova without difficulty, provided the follicles are matured.4. PMS levels of 500 and 1000 i.u. do not cause any apparent ovarian abnormalities apart from superovulation. A very high proportion of all follicles developed rupture and form apparently normal corpora lutea. PMS at 2000 i.u. causes lutein cysts and ovulation may be inhibited.5. PMS at 500 and 1000 i.u. causes no cyclic abnormalities, although cycle length is slightly shortened. In the event of the ewe failing to conceive, the subsequent oestrus is normal, and ovulation and fertilization of the ova occur.6. Commercial PMS is probably as effective as fresh PMS provided it is correctly standardized. There seems no reason to suspect differences in multiple ovulating efficiency between different batches of fresh PMS.7. While breed differences in response possibly exist they were not observed in these experiments. Nor were differences apparently related to the relative time of injection within the breeding season.8. There is an ovarian weight-PMS level, doseresponse relationship which is almost entirely accounted for by the numbers of corpora lutea and hence of luteal tissue.9. Multiple-ovulated ova are highly fertilizable. However, when fifteen or more are shed the rate of tubal transport is considerably accelerated and the proportion fertilized appears to fall. One- and two- cell ova have been recovered from the uterus within 48 hr. of service. Nine fertilized ova have been recovered from one ewe.10. Considerable embryonic mortality occurs before attachment of the blastocysts. None the less, multiple impregnation does occur but is followed by further early death. Up to thirteen attachments have been observed in one ewe, but all but three were showing signs of regression by the 19th day.11. Post-attachment mortality takes the form of an initial retardation commencing about the 15th day, embryos apparently dying a day or so later. The peak of mortality occurs between the 17th and 19th day, by which time definite signs of resorption are apparent.12. By 21 days equilibrium has been reached, the mean numbers of survivals of those ewes pregnant being some 260%. This level is maintained without further loss until the 68th day. Several cases of four normal foetuses were noted up to the 41st day, and one uterus containing six perfectly normal foetuses was recovered at 61 days.13. The overall fertility indicated by these slaughterhouse ewes varies with the level of PMS administered. While equilibrium is achieved by animals conceiving, at about 250–260% viable foetuses, regardless of the dose injected, there is increasing proportion of returns to service with increasing dosage. For the most part this appears due to hormonal imbalance at the time of ovulation and fertilization when an excessive number (〉 15) ova are shed. This results in accelerated ovum transport through the tubes and lowered rate of fertilization. Between ovulation rates of 4 and 12, produced by 500 i.u., rate of conception is extremely high. Of twenty-five ewes receiving 500 i.u. PMS, twenty-three (92%) conceived to the first fertile service. The conception rates were reduced to 80 and 60% by 1000 and 2000 i.u. respectively.14. Although after the end of the 3rd week there is no direct evidence of further foetal mortality, the percentage of lambs born in the flock ewes injected with 500 i.u. PMS was only 192% of those lambing or 167% of all ewes mated (147% for controls). This indicates a loss late in pregnancy. This can in part accounted for by abortion; one ewe aborted, due, is believed, to her carrying more lambs than she was physically capable of retaining.15. OffifteenflockSuffolksinjectedinthe 2nd year with 500 i.u. PMS, thirteen lambed, one aborted and one did not conceive. The thirteen ewes lambing presented twenty-five lambs, including one set triplets and one of quadruplets. All the latter were viable, but two sets of twins were bom dead. One triplet was lost on fostering and one other lamb was lost, so nineteen were tailed. Of fifteen controls, all lambed, giving twenty-one lambs bom of which twenty survived. Conception to first fertile service was higher in the injected than in the control ewes. In the preceding year when 1000 i.u. was given, both conception and lambing rates were appreciably lowered as compared with untreated controls. The significance of this in respect to the level of PMS administered is stressed.16. It is concluded that the major part of the embryonic loss is due to a uterine environment which is incapable of supporting more than a limited number of embryos. It is considered possible that there are breed differences in this, and that each breed, and individual within the breed, has ‘Maximum Potential Fertility’.17. This ‘Maximum Potential Fertility’ is not attained in normal breeding practice, since the number of ova shed by the ewe tends to constitute a limiting factor. Use of a level of PMS which will induce between three and ten ovulations—in the case of this experiment, 500 i.u.—removes this limiting factor, giving the individual full opportunity to express its full potential breeding capabilities.18. There is some indication that the use of PMS in lambs may not give good results, and its use for the while should be restricted to mature ewes.19. Since 500 i.u. PMS has resulted in a higher conception rate to first service and to a greater number of lambs born, it is apparent that this technique of injecting on the 12th day of the cycle a level of PMS which will result in a moderate number of ovulations is worthy of exhaustive field trials, notwithstanding the high post-natal mortality observed in the few cases which were allowed to go to term.20. In view of the higher indicated fertility of the slaughtered ewes which were mainly Border Leicester cross and Dorset × Cheviots—normally very highly fertile ewes as compared with the flock Suffolks—it is considered possible that this technique will yield best results with more highly fertile breeds.21. To have any hope for successful increase of fertility in mammals following gonadotrophin treatment the hormone must be administered at a time and at such a concentration that it will augment, but not upset, normal hypophysial and ovarian function.