ALBERT

Description: 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.

Description: 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from that in soils of other arid regions.I am indebted to H. Greene and E. M. Crowther for access to their earlier unpublished work on nitrification in Gezira soil, and to O. W. Snow of this Service for advice during the course of this work.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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’.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: SUMMARYHerbage samples were collected in late June, and again in early September (1987) from permanent mountain meadows situated in North-western Spain (León). Botanical composition was determined by grouping the species into grasses, legumes and herbaceous ‘weeds’. Rumen degradability of the dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) of the botanical groups in each harvest season was determined by the nylon-bag technique.Grasses and legumes differed in their degradation characteristics, and the comparisons between forage species were different for the two harvest seasons. There were no significant differences between September grasses, June legumes and September legumes in the potential degradabilities of the DM (86·9, 87·1 and 88·4%) and CP (94·2, 92·4 and 93·8%). The NDF of grasses harvested in September was degraded to a greater extent (80·6%) than that of legumes from both harvests (70·9 and 73·6% in June and September respectively). However, June grasses showed significantly lower potential degradabilities for the DM (77·0 %), CP (84·3%) and cell wall (65·9%). Legumes were degraded at a faster rate than grasses (mean DM degradation rates of 0·143 and 0·057 respectively), and lag times were longer for grasses (4·7 h) than for legumes (2·5 h). Rumen degradation characteristics of the herbaceous ‘weeds’ were estimated, but it should be remembered that many other factors may limit their utilization by ruminants.It was concluded that the major constraint to the nutritive value of these permanent swards would be the maturity of the grasses harvested in June, which markedly reduced the rumen degradability of the forages.

Description: SUMMARYQuinoa produces a cereal-like grain with a higher protein content and a better balanced amino acid composition than the major cereals. It is cultivated at high altitudes in the Andes, and is believed to have potential for temperate regions. In the development of quinoa as an arable break crop, sowing date, sowing rate and row spacing are identified as agronomic variables having a high priority for investigation. The variety Baer, from high latitudes at sea-level in Chile, and the variety Blanca de Junin, from the inter-Andean valleys of Peru, were sown on 25 March, 14 April and 7 May 1982 at spacings between rows of 0·8 and 0·4 m and sowing rates within rows of 0·2, 0·4 and 0·6 g/m, at Cambridge, England. These varieties were chosen for their strongly contrasting origins and plant types. In another experiment sown on 15 March 1984, Blanca de Junin was replaced by another valley variety, Amarilla de Marangani, somewhat better adapted for cultivation in England. Between-row spacings of 0·4 and 0·2 m, and sowing rates of 15, 20 and 30 kg seed/ha were used. Weed competition was more intense after later sowings, causing the plots sown in May to be abandoned. At the higher sowing rates, plants were shorter, a higher proportion were stunted, branching was reduced and maturity was earlier. These effects were more marked in the valley varieties, particularly Blanca de Junin. Increases in within-row density caused greater increases in competition effects than corresponding reductions in row width, except for the effect on the proportion of branched plants. The highest grain yield, 6·96 t/ha, was obtained with Baer sown in March in rows 0·2 m apart at 20 kg seed/ha. However, Amarilla de Marangani produced a higher yield at 30 kg seed/ha than at 20 kg seed/ha, which is surprising since valley varieties are normally sown with low target population densities or in intercrop, and Amarilla de Marangani was, in other respects, less tolerant of competition than Baer. The implications of these results for the cultivation of quinoa in mechanized farming systems, both in temperate and in highland tropical regions, are discussed.

Description: SUMMARYHand harvesting is a major constraint to lentil production in North Africa and West Asia. This study, in north Syria, compared hand harvesting, cutting by mower (double-knife) and cutting with angled blades on two lentil cultivars differing in standing ability and using two sowing methods (broadcast and drilled) both with and without the use of a heavy bar for field levelling in the 1984/85 season. Seven treatments were selected for testing in five locations in the 1985/86 season; and in the 1986/87 and 1987/88 seasons, agronomic comparisons of mowing v. hand harvesting were conducted on five farmers' fields.Both machine methods of harvesting resulted in significant harvest losses compared with hand harvesting. The angled blades performed well on a ridged broadcast crop, but tended to mix soil with the harvested crop. The loss of straw associated with harvesting by mower was reduced by levelling the seedbed after sowing. The superiority in seed yield of cultivar 78S26002 over the local cultivar increased from 9% when hand harvested to 39% with mowing because of its lower likelihood of lodging. In the 1986/87 and 1987/88 seasons, the seed yield from a hand harvest was 1650 kg/ha compared with 1508 kg/ha following harvest by mower, representing a loss of 8·6% from mechanization. The corresponding straw loss was 16·6% of the mean from a hand harvest of 2140 kg straw/ha. However, the harvest losses from mechanical harvesting by mower were compensated for by the reduced labour costs compared with hand harvesting.

Description: SUMMARYThe effect of phosphorus fertilizer on the performance of an improved semi-dwarf (100 cm), long duration (170 days), photosensitive rice variety CR 1016, grown under conditions of intermediate deepwater (15–50 cm) and simulated flash flooding (80 cm), was investigated at Cuttack, India in 1985, 1987 and 1988. Growth and yield of rice subjected to overhead flash flooding (complete submergence) at the vegetative stage for 10 days was decreased significantly compared with partial submergence in water of intermediate depth. The adverse effect of complete submergence was due to greater tiller mortality and lower number and/or weight of panicles at maturity. Rice plants fertilized with P tolerated flooding better and produced significantly higher grain yields than when no P was applied. There was no significant effect of P application on the crop grown under natural unsubmerged conditions, except when it was raised in the same plots as the previous year and may therefore have benefited from residual effects. Therefore, application of 8.7–17.5 kg P/ha along with 60 kg N and 16.7 kg K/ha at sowing was essential to overcome the deleterious effects of submergence on rice grown under waterlogged conditions.

Description: SUMMARYOptimum applications of N fertilizer, Nopt have been related successfully to the amount of mineral N in the soil, Nmin in some parts of Europe but not always in the UK. If there is a body of mineral N, QN, that ultimately lessens the need for N fertilizer, it will not remain constant in its amount or its position. Mineralization will add to QN, while the nitrate component of QN will be leached downwards.Also, part of QN will be taken up into the crop where it will continue to lessen the need for fertilizer N but will be safe from leaching. A computer model was used to simulate these processes for 23 experiments, covering five sites and five years, in which N opt had been estimated. From these simulations we derived trial values of QN that took account of mineral N to a series of depths on a series of dates. For each date we used the trial values to find the depth for which Nopt was best correlated with QN andassumed that this was the depth, dL, of the lower boundary of QN on that date. Thus dL was a collective value for all 23 experiments. The value of dLincreased throughout the winter and the spring and was very closely related to the cumulative average drainage through 0·5 m soil at Rothamsted. By 15 April, dL, was 1·66 m, a depth that was compatible with observations by others that winter wheat can remove mineral N to a depth of at least 1·5 m. We inferred two likely reasons why Nmin may fail as a predictor of Nopt in the UK: insufficient depth of sampling, and too wide a spread of sampling dates. The values of Nopt were shown to be related satisfactorily to the values of QN computed, without any measurements of mineral N, for appropriate depths on single dates.

Description: SUMMARYIn 1989 three experiments with up to three different treatments each were carried out in North Germany to determine the ammonia flux densities after the application of liquid slurry using the micrometeorological mass balance method.In Expts 1 and 2, pig slurry was applied with a conventional surface spreader to wheat stubble. The results demonstrated the influence of meteorological conditions and that of incorporation on the extent of ammonia volatilization. In comparison to warm and windy conditions, NH3 losses decreased from 56% of the NH4-N applied to wheat stubble to 42% during a cool and rainy period. When slurry was incorporated immediately into the soil, ammonia losses were significantly reduced to 20 and 10%, respectively, of the applied NH4-N. The highest losses (67% NH4-N) were found when slurry was applied during warm weather on wheat stubble covered with chopped straw. Soil cultivation of the wheat stubble before the application of slurry diminished the ammonia emission from 42 to 28% of the NH4-N.In Expt 3, cattle slurry was applied to rape. It was found that compared with a conventional surface spreader the ammonia volatilization was reduced from 68 to 58% of the NH4-N when an alternative distribution system consisting of drag hoses was used for the application.

Description: SUMMARYThe nutritive value of taro leaf (Colocasia esculenta) silage, with or without various crop or crop byproducts as additives, was evaluated in two experiments in Western Samoa in 1988 and 1989. In Experiment 1, laboratory silos were used to assess the quality of eight taro leaf silages which were either ensiled fresh or wilted overnight. Taro leaf ensiled alone was poorly preserved with a pH of 5·4 and high concentrations of ammonia-N and volatile fatty acids. In contrast, silages with crop byproduct additives rich in water soluble carbohydrates (WSC), mainly molasses, ripe banana or papaya pulp, were of high quality with pH levels of c. 4 and low concentrations of volatiles. Copra meal, although low in WSC, was able to produce a satisfactory silage when added to taro leaf through its ability to restrict fermentation.Despite only a small increase (14·2%) in silage dry matter (DM) content, wilting of taro leaves resulted in silage of significantly higher quality than that made from fresh leaves. Most of the benefit of wilting was attributed to better fermentation conditions rather than a restricted fermentation.Two of the better silages from Experiment 1, taro/molasses and taro/banana, were prepared on a larger scale in earth pits and fed to goats in a second experiment. Both silages were highly palatable and digestible; DM intakes of 47 and 63 g/kg W0·75 per day and organic matter digestibilities of 69·0 and 74·9% were recorded for the banana and molasses silages, respectively.It was concluded that taro leaf is a suitable forage for ensilage, and when combined with additives rich in WSC, a forage of high nutritive value can be produced.

Description: SUMMARYLentils were grown in 1984/85, 1985/86 and 1988/89 in Canterbury, New Zealand. Results showed that lentil canopies were capable of intercepting a maximum of 95% of incident solar radiation at a leaf area index of 7. Autumn sowings attained canopy closure, but late spring sowings did not. At the highest population density used (500 plants/m2), only 65% of incident solar radiation was intercepted by a late spring-sown crop. In all three growing seasons there was a highly significant positive relationship between cumulative absorbed radiation and dry matter (DM) production. Over all seasons, 1·6 g DM/m2 was produced per MJ of absorbed photosynthetically active radiation (PAR). The final utilization coefficient (u) was not affected by sowing date but in a late-sown, diseased crop, u was 38% less than in a disease free crop. In 1984/85, dryland crops had a utilization coefficient of 1·39 while irrigated crops had a u of 1·54. Growth efficiency of lentils was low, at 2·5%.

Description: SUMMARYTwo experiments, each involving a set of six sweet potato clones, the first set developed in sites differing in altitude, and the second in sites differing in soil type, were done at three locations in 4 years in Cameroon. Data obtained were subjected to analyses of variance to determine the presence of genotype × environment (G × E) interactions, and to joint regression analyses to measure the performance of clones across environments. The first experiment produced higher yields and contained more stable clones than the second. In both experiments, mean yields were almost twice as high in 1984 (21·1 t/ha) as in each of the other years (c. 11·0 t/ha), and highest at Nyombe (18·0 t/ha). In Expt 1, the G × E interaction mainly concerned interaction with location, whereas in Expt 2 it concerned interaction with years.Clones 1611 (Expt 1) and 048 (Expt 2) yielded above average and gave linear regressions significantly above unity (b 〉 1·0) for most traits, indicating specific adaptation to high-yielding environments and hence below average stability. Clones 1112, 1639 and TIbl (Expt I) yielded above average and had regression slopes equal to unity (b = 1·0), indicating average stability and thus general adaptability. Clones TIb2 (Expt 1) and 1487 (Expt 2) produced below average yields (b 〈 1·0), indicating specific adaptation to low-yielding environments. Since sweet potato is grown mainly for human consumption in Cameroon, a preferred clone must have stable marketable yields. Only clones 1112, TIbl and 1639 could be considered desirable for release to growers.

Description: SUMMARYChinoli (Brassica campestris subsp. oleifera × subsp. chinensis), Marnoo and Apetalous (B. napus), with contrasting morphological characters, were compared over four seasons in Tasmania in 1985/86 and 1986/87. The total water use estimated from a depth of 70 cm increased in proportion to irrigations. Before irrigation all the crops had a similar pattern of moisture extraction but differences between the lines, and due to irrigations, emerged after the irrigation treatments. The genotypic differences were clearer in the winter sowing of 1986/87, when the growing season was longer. Apetalous, when unirrigated, extracted a greater amount of water from the lower, wetter regions of the soil profile, particularly in the longer winter sowing when its water use was the same as in the treatment receiving one irrigation. With consistently higher stomatal conductance, Apetalous used more water than chinoli or Marnoo. It also maintained a higher turgor at lower osmotic potentials, suggesting a greater degree of drought tolerance than found in the short duration chinoli which, although it had a lower water use, also gave lower seed yields.

Description: SUMMARYSpring barley and spring oats were strip-seeded into crops of the white clover cultivar Alice at Hereford in 1987 and cultivar S184 at Aberystwyth in 1988. Drilling was done with or without a band-spray of glyphosate, a moderate or low (1988 only) dose of paraquat or into plots where the clover had been killed by herbicide 2 months previously.In the first experiment, initial cereal emergence was sparse; growth was suppressed in the unchecked (unsprayed) clover base but was vigorous in the clover-free plots; the cereals also became dominant in the swards sprayed with herbicide. Whole-crop yields in mid-August were 13, 3–4 and 8–10 t DM/ha in the plots in which clover was killed, unchecked or checked with herbicide. Clover contributed 4–12% of the harvested herbage in the latter treatment. This treatment also yielded c. 70 % as much N, carbohydrate and fibre as that without clover. Grain yields exceeded 7 t/ha without clover but were only 0·3 t/ha for barley and 1·1 t/ha for oats with unchecked clover; in the checked clover plots, barley yielded 60% and oats 78% as much as on the clover-free plots. Four and 5 weeks after whole-crop harvest, residual clover growth was 27 and 39% of that on unchecked plots for oats and barley, respectively.In the second experiment, the cereals emerged thickly but were later dominated by the clover, and an equitable balance was achieved only with the larger dose of paraquat. However, the oat cultivar Emrys was suppressed less than the tall barley cultivar Dandy; the short barley cultivar Digger was the most suppressed. Mean whole-crop yields were 11 t/ha in the treatment without clover, about half this in the unchecked bases and c. 9 t/ha with the larger dose of paraquat. Differences in chemical composition reflected much larger clover contents in 1988 than in 1987. Yields of N and water-soluble carbohydrate were at least as large or larger with moderate paraquat than for the clover-free plots. Grain yields ranged from 5·6 to 6·9 t/ha for the three cereal cultivars without clover but were negligible to very small in the unchecked and band-sprayed treatments, and were 3·4 and 2·0 t/ha for oats and barley, respectively, with the larger dose of paraquat. Residual stolon weights, 70–80 days after whole-crop harvest, greatly exceeded initial values in all treatments. They were smallest following the larger dose of paraquat, and larger in Digger than in Dandy, which in turn was larger than in Emrys.It is concluded that the concept of growing cereals in a clover base shows potential as a low input–moderate output system of cereal production. However, further longer term work is needed on regulation of the cereal–clover balance, on the release and uptake of N and the environmental effects of the technique.

Description: SUMMARYField experiments were conducted at Fagu and Shimla in India in 1983 and 1984 to study the effect of thiourea (0 and 5 kg/ha) on tuber yield of potatoes and uptake of P with different rates of fertilizer P (0, 22, 33, 44 and 66 kg/ha). Application of phosphorus and thiourea, both alone and in combination, increased tuber yield and uptake of P significantly at both the locations in both years.

Description: SUMMARYIn a 2-year field experiment at Hohenheim in 1987–88, with an intact or partly deflowered indeterminate cultivar and a determinate cultivar, light interception and dry matter production were highest in crops grown in isometric stands (equal distances between plants), lowest in double rows and intermediate in single rows. Dry matter production was greater at high than at low population density and in the wetter and cooler weather of 1987. Population density had a greater effect on DM production than on light interception. The greater leaf canopies under high density and in 1987 (Stützel & Aufhammer 1991) reduced light extinction coefficients. In the determinate cultivar, light extinction coefficients were consistently higher and light use efficiencies were consistently lower than in the indeterminate cultivar. Deflowering the indeterminate genotype and different planting designs did not change light use efficiencies and light extinction coefficients. In general, differences in light use efficiencies were inversely related to differences in light extinction coefficients.

Description: SUMMARYIn studies of two indeterminate cultivars in field experiments in 1985 and 1986 at Hohenheim University, the hierarchy within the reproductive storage system of field bean plants was manipulated by removal of inflorescences at various growth stages and nodes. Shading reduced pod set and seed weight mainly at basal nodes. Increasing plant population density reduced seed yield traits at all nodes. Removal of basal inflorescences increased pod set and seed weight at the remaining nodes, especially the lower ones. The favourable effects were greater under high light intensities and in sparse stands. The growth stages at which the basal inflorescences were removed and the removal of apical inflorescences were of minor importance.