ALBERT

Notes: The main object of the experiment was to assess the effect of the relative proportion of non-protein nitrogen (NPN) to total nitrogen in silage on digestion in the sheep. Four unwilted perennial ryegrass silages were made with the addition of formic acid at 0, 2·2, 4·2 and 5·2 litres t-1 to provide foods with NPN proportions reducing from 0·26 to 0·20 of the total N. The digestion of the silages was studied in a 4 × 4 Latin Square experiment with sheep cannulated in the rumen, proximal duodenum and terminal ileum.Results for organic matter (OM), cellulose and N showed no major difference between silages in their digestion in the rumen, small intestine and caecum and colon, though small differences (P 〈0·25) in rumen fermentation pattern and in the proportion of digestible OM disappearing in the small intestine were observed. Concentrations of ammonia N in the rumen and rates of rumen bacterial protein synthesis did not differ significantly between silages and there were no treatment effects on the passage of individual amino acids to the small intestine. The results indicate that the proportions of NPN to total N in the silages examined had little influence on the efficiency of silage N utilization in the rumen or on the passage of undegraded dietary protein to the small intestine.

Notes: Two experiments were carried out to determine whether the differences in intake and feeding value previously shown between two grass cultivars when offered to ruminants as chopped artificially dehydrated (dried) material could also be demonstrated when the grasses were offered in other forms. Two cultivars of tetraploid Italian ryegrass (Lolium multiflorum), Sabalan and Tetila, were established in the same field in 1975. In 1976 they were grazed and conserved (two cuts of primary growth) as dried material or as silage.The composition of the herbage selected at pasture and conserved showed higher concentrations of normal detergent fibre and acid detergent fibre in the dry matter for Tetila than for Sabalan, but differences between cultivars in digestibility were small. In both grazing and winter feeding trials differences in voluntary intake between the two cultivars were not significant, but at pasture young beef cattle spent less time grazing and tended to spend more time ruminating on Tetila than Sabalan. There was no measure of animal performance at pasture but liveweight gain was 15% higher for Sabalan than Tetila when both were offered to young beef cattle as the sole feed of dried grass or of silage. The voluntary intakes of the three forms of feed were very similar, which in part reflected a similarity in digestibility. However, gains were lower for calves given silage than those given dried grass. This may have been due to a lower efficiency in the utilization of the nitrogeneous components of silage for tissue growth than those of dried grass.

Notes: Four grass silages, all made in mid-July from second-harvest perennial ryegrass swards, were compared in a 16-week feeding experiment with twelve Ayrshire cows. Two silages were unwilted and two wilted. All the silages received formic acid (‘Add-F’) at the rate of 3 litres t-1 either with formalin at the rate of 1 litre t-1 or without formalin. The unwilted and wilted silages had mean dry matter (DM) concentrations of 200 and 243 g kg-1, and in vitro D-values of 0·293 and 0·272 respectively. The silages were offered ad libitum plus 6 kg concentrates per cow per day. The daily intakes of unwilted and wilted silage DM were 10·2 and 9·2 kg per cow respectively on the formic acid treatment, and 10·2 and 9·2 kg on the formic acid + formalin treatment. The mean daily milk yield on the unwilted silage treatments was 19·2 kg per cow which was significantly higher than the yield of 17·2 kg per cow on the wilted silage treatments. The formalin had no significant effect on milk yield. The four silage treatments had small and non-significant effects on milk composition. It is concluded that the unwilted silages, which had excellent fermentation characteristics, were superior to the wilted silages as a feed for dairy cows.

Notes: Book review in this article Forage Evaluation: Concepts and Techniques Edited by J. L. Wheeler and R. D. Mochrie Improved Feeding of Cattle and Sheep By P. N. Wilson and T. D. A. Brigstocke Nitrogen Cycling in West African Ecosystems Edited by T. Rosswall Land Evaluation By S. G. McRae and C. P. Burnham

Notes: Three field experiments showed that perennial ryegrass can be successfully slot-seeded into an existing Festuca-Agrostis sward. Ryegrass survival was satisfactory in all cases but was improved on a low fertility site by the application of fertilizer N, P and K in the slot at sowing.The effect of varying inter-row spacing from 37·2 to 15 cm was measured in a 3-year experiment. In year one, involving seven cuts, slot-seeding increased total herbage dry matter harvested by a mean value of 17%; inter-row distances of 22·2-30 cm gave the optimal combination of ryegrass + old sward herbage. Differences in yield between inter-row spacings declined in the subsequent two years, as the rows of ryegrass thickened. Ryegrass digestibility (measured only in year two, from six cuts) was higher than that of the old sward; total metabolizable energy harvested from 15-cm rows was 20% higher than that from unsown controls. Increasing N input from 200 to 400 kg ha-1, starting in year two, only produced a significant increase in total herbage harvested in year three but proved effective in increasing the ryegrass contribution from the wider spaced rows.

Notes: In three separate feeding experiments using a total of thirty individually-housed Ayrshire cows three silages made from perennial ryegrass were given ad libitum together with supplements of four different hays in the long form. The in vitro D-values of the silages ranged from 0·298 to 0·283, and the hays from 0·280 to 0·200. The daily intake of hay DM varied from 0·2 to 4·2 kg per cow and was given either without or with a daily maximum of 2·2 kg concentrate DM containing 379–527 g CP per kg DM. On average, 1 kg hay DM decreased silage intake by 0·24 kg DM with a range of 0·21–1·20 kg. The hay supplements had only small and non-significant effects on total DM intake, milk yield and milk composition, but increased the daily intake of drinking water. In three behavioural studies, the eating and ruminating times expressed as min per kg DM did not differ significantly between the various supplement treatments. It is concluded that hay has only a marginal value as a supplement for grass silage, although the hay could serve as a useful ‘buffer’ feed if the amount of silage was limited.

Notes: Two areas of an early-heading perennial ryegrass cv. Cropper were harvested by either a precision-chop or a flail harvester at around 50% ear emergence (15 May 1978) and 14d later (29 May). Formic acid (85%) was applied at the rate of 2·2 litres t-1. Mature crossbred wethers were used in a 2 × 2 factorial design to determine the effect of stage of maturity and method of harvesting (chop length) on the in vivo digestibilities of formic acid-treated grass in experiment 1 and formic acid silage in experiment 2. Apparent digestibility coefficients were determined at a fixed level of feeding for both grass and silage and at ad libitum access to feed for silage only.There were no significant differences in the concentrations of crude protein (CP), ether extract (EE), acid-detergent fibre (ADF) or acid-detergent lignin (ADL) in grass or silages of differing chop lengths but the later cut forages had significantly higher ADF and ADL concentrations and lower CP concentrations than the early-cut forages. The ADF and ADL concentrations were also higher in the silages than in the corresponding grasses.In general, the fermentation characteristics of precision-chopped silage were better than for the corresponding flail-cut silage but date of harvest was a more important determinant of quality and the late, flail-cut silage had the highest butyrate and ammonia N concentrations and the highest pH (411) of any treatment. There was a significantly higher intake of precision-chopped as compared with flail-cut silage with both the early-and the late-cut silage but there were no significant differences attributable to stage of maturity (i.e. date of harvest) or significant interaction between chop length and maturity. The slightly increased intake of early harvested, precision-chopped silage as compared with late precision-chopped silage was not significant.Dry matter digestibility (DMD) of the grass decreased at a rate of 0004 units d-1 post 50% ear emergence. The results of experiment 2 indicated a decrease of 0·207 units d-1 in silage fed at a similar level. The late-cut silage (DMD 0·292, mean of both harvesting treatments) thus had a significantly lower digestibility than the corresponding grass (mean DMD 0·247). Chop length had a variable influence on the DMD of both grass and silage fed at a fixed level but treatment differences were non-significant. However, a trend towards higher digestibility of flail-cut as compared with precision-chopped silage was apparent and this became statistically significant when the animals were allowed ad libitum access to feed. This may be a response to the generally lower intake of flail-cut silage.

Notes: Book review in this article Weed and Pasture Management in South Africa Edited by N. M. Tainton Collecting and testing tropical forage plants Edited by R. J. Clements and D. G. Cameron Herbage Intake by Grazing Dairy Cows By J. A. C. Meijs

Notes: Two experiments were carried out to evaluate propionic acid-treated hay as a feed for sheep in which eighteen ewes (experiment 1) and eighteen ewe lambs (experiment 2) were fed ad libitum on hay only. At feeding, the propionic acid-treated hays had higher D-values and water-soluble carbohydrate concentrations, but a lower dry matter concentration, than the untreated hays. The voluntary feed intake and liveweight gain of the sheep fed on two acid-treated hays and on an untreated hay in experiment 1 were similar. In the second experiment an acid-treated moist hay was eaten in greater amounts by the sheep and liveweight gains were greater than on the corresponding untreated hay, but were not significantly different from those of sheep fed on field-cured hay.

Notes: Six varieties of white clover, each grown with perennial ryegrass, four intervals between cuts and two levels of applied nitrogen in all combinations, were compared in a field experiment during the first 27 months after sowing. Information about yields, crop fractions, heights and ryegrass tillers has been presented in an earlier paper (Wilman and Asiegbu, 1982). The present paper is concerned with the more detailed studies of white clover, which help to explain the yield results and contribute to the understanding of the response of this species to management when grown in competition with grass.Increasing the interval between harvests increased the length of clover stolon per unit area of ground and increased stolon diameter, petiole length, weight per leaf and number of leaves harvested as a proportion of the number present in the sward while only slightly reducing the rate of leaf emergence, helping to explain the positive effect of increasing the interval on clover yield noted in the earlier paper. During regrowth, successive leaves had longer petioles and the length of individual petioles increased beyond the stage at which the leaflets were fully opened. Weight per leaf in clover increased considerably from April to June and declined to below the April value by October. It was shown that weight per leaf can be greatly increased by increasing the interval between harvests without reducing the number of leaves harvested per unit area per year. The stolon length measurements provided some support for the view that medium large-leaved varieties of white clover can with advantage be defoliated rather less frequently than small-leaved varieties. Stolon length was less adversely affected by applied N in the medium large- than in the small-leaved varieties. The small-leaved varieties had thinner stolons than the medium large-leaved varieties but about twice the stolon length when no N was applied, and a relatively high proportion of leaves which escaped defoliation. The application of N reduced stolon diameter, increased petiole length and had little or no effect on weight per clover leaf.

Notes: Data from twenty-two comparisons carried out at ADAS Experimental Husbandary Farms are used to compare untreated and formic acid-treated silages. Additive treatment led to an improved fermentation in some crops, particularly those of low DM concentration (〈262 g kg-1). Where this occurred there were associated benefits in silage digestibility (+0·234 units), intake (+16%) and the growth rate of young cattle (+0·28 kg d-1). Where the fermentation of the untreated silage was good, both digestibility and animal performance associated with treated and untreated silages were similar. It is suggested that the justification for using formic acid in a commercial situation is thus restricted to occasions where the untreated crop would be liable to develop a clostridial fermentation. These may be when crops contain less than 35 g water-soluble carbohydrate kg-1.

Notes: The change in structure of continuously grazed versus infrequently cut swards of perennial ryegrass (Lolium perenne L), cv. S23, was investigated during their first full harvest year. Measurements were made from early May until late September. The intensity of stocking by sheep in the grazed sward was adjusted in an attempt to maintain a high level of radiation interception and the cut sward was harvested at approximately monthly intervals.The herbage mass, lamina area index and radiation interception of the cut sward varied in a cyclic pattern between harvests but in the grazed sward these parameters showed considerably less variation, although they all increased early in the season and then declined later. The proportion of dead material above ground increased throughout the season in both sward types but was more marked in the grazed sward.There were major differences between the grazed and cut swards in the number of tillers per unit ground area; the difference became more marked throughout the season and by September the tiller densities in the grazed and cut swards were 3·204 m-2 and 6·203 m-2 respectively. Divergence in tiller density was associated with differences in specific stem weight and leaf area per tiller.Rates of appearance and death of leaves on tillers in the grazed sward were determined. During May, leaf appearance exceeded leaf death but this was reversed in June. During the rest of the season as a new leaf appeared on a tiller so the oldest leaf died.

Notes: A rising-plate meter was used in a double sampling technique to measure the herbage mass of rotationally grazed perennial ryegrass-white clover swards over a period of 2 years. The meter was calibrated by developing a linear regression between meter reading and herbage dry matter mass as measured by cutting 0·2-m2 quadrats to ground level.There was a strong relationship between meter reading and herbage mass, and correlation coefficients were consistently 0·2 or above. The calibration regression was normally constant for extended periods, especially over the winter and spring. The relationship was more variable over the summer but appeared to follow a pattern that was to some extent repeatable between years. The slope of the regression (kg DM ha-1 cm-1) was 312 and 267 in the two winters and reached values of 800 and 452 in the two summers. The calibration relationship was adequately described by a linear model over the winter and spring but there was a tendency for a curved relationship in mid-to late summer.The standard pooled regression found with winter ryegrass-clover swards was not applicable to the more erect prairie grass, and the standard regression overestimated slightly the yield of heavily grazed swards. There was no evidence of a difference in relationship between irrigated and non-irrigated swards over the summer.The individual meter readings could be used to develop a useful diagrammatic picture of the changes that occurred in sward structure as the pastures were subjected to different managements and this could be used to illustrate problem areas in pasture management.The meter was useful in overcoming the problem of variability of herbage mass within paddocks and could give precise estimates of herbage mass, especially when it was possible to use a pooled regression encompassing a large number of calibration cuts. In these cases the meter could be used to detect differences of about 8%.

Notes: Varieties of Italian, perennial and Italian × perennial ryegrasses, tall fescue and cocksfoot were used to determine the effects of soil moisture on grass growth. Weather conditions were monitored and herbage accumulation, leaf extension rate, leaf appearance rate and tillering were recorded under natural (control), covered and irrigated treatments.Water deficit reduced crop growth rate in the spring and drought was the major factor influencing crop growth rates in all varieties during the summer. The ryegrasses appeared most sensitive to drought, and particularly poor recovery growth was exhibited by the Italian ryegrass RvP and the hybrid ryegrass Snowdon.Leaf extension rate and leaf appearance rate were both reduced by increasing soil water deficit. Herbage accumulation was increased by irrigation when potential soil water deficits were greater than 100 mm. When water deficits were large, irrigation increased leaf extension more than leaf appearance or tiller number. Increasing moisture deficit had a greater effect upon tiller number than on leaf extension.

Notes: Records of grassland productivity were kept for 2 years on 152 dairy and 179 beef farms. Results were collated for six lowland zones, delineated primarily on the basis of average rainfall, and an upland zone. Contemporary and long-term average meteorological records were also collected.In most of the lowland zones stocking rates and use of fertilizer N were similar, but utilized metabolizable energy (UME) output from grass varied; it was 25% higher in the wet, cool zone of north-west England and east Wales than in the dry zone of eastern England. The ranking of zones for utilized output corresponded closely with the ranking for summer rainfall.On upland farms stocking rate was 25% lower and UME output 15% lower than on lowland farms, but this was achieved from little more than half the N input.The differences between zones were similar to those shown in other published farm data. They also showed a similar trend to that demonstrated in grass cutting experiments. This suggests that farmers were, on average, able to exploit the extra grass grown in wetter climates. The incidence of difficult topography and impeded drainage was similar in dry and wet zones, but did have a more serious effect in the wet zones. The much higher level of concentrate feeding in the driest zone may have reduced the utilization of grass.

Notes: Twelve varieties of cocksfoot, Dactylis glomerata L., were analysed for three mineral elements (Na, K, Ca) and their dry matter (DM) yields were measured in pot and field trials. Among these characteristics there were strong varietal differences in Na concentration, whereas in other cases the varietal differences were less significant. The concentrations of individual mineral elements were, in most cases, independent of yield and of one another.Parent plants and their clonal derivatives were highly correlated in Na and Ca concentration as well as in DM yield. Tiller size or position on the parental plant had no significant effects on the mineral concentrations or DM yields of clones derived from separated tillers.Within varieties continuous variation was observed for Na concentration and the range of variation increased with increasing mean Na concentration. When plants were grown under different experimental conditions there was a high repeatability in Na concentration within varieties over cuts and years. This result was taken as an indication of a strong genetic basis for Na concentration. The results obtained in this study show that it is possible to develop grass varieties of defined potential Na concentration.

Notes: Samples of 39 perennial ryegrass (Lolium perenne L.) and 24 Italian ryegrass (Lolium multiflorum Lam.) commercial seed-lots used at the Grassland Research Institute between 1974 and 1978 were examined for the presence of seed-borne Drechslera species. The five species of Drechslera isolated from the seeds were D. andersenii, D. siccans, D. nobleae, D. sorokiniana and an unidentified Drechslera sp.A high proportion of the seed-lots were infected but levels of infection were low except in the perennial ryegrass cv. S24. Infection was located more commonly inside the caryopses than externally on the lemmas and paleae, and about 12% of the seedlings growing from infected seeds were infected. The species recovered in the seedlings were the same as those observed on the seeds.There was no relationship between level of seed infection and level of damage observed in the field in the autumn of the first harvest year.

Notes: A high risk of pest damage to seedlings of white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.) was shown to exist after reseeding with a slot-seeder. Damage varied between years and sites; white clover appeared to be more affected than perennial ryegrass. Insecticides of feasible commercial use (chlorpyrifos granules and γ-HCH seed treatment) were found to prevent damage. There was no evidence of phytotoxicity from any of the pesticides studied at the dose rates used in the field.

Notes: The statistical properties and applicability of the Dry-Weight-Rank (DWR) method of pasture sampling are examined. Formulae for the expected value and variance of the DWR estimates are presented.The extent of bias in DWR is examined using several mathematical models. DWR is shown to break down when estimating multinomial proportions; however it provides good estimates for a subset of models simulated from a class of compound probability distributions.The success of DWR in practice does not rest on a theoretical basis. It appears to be a remarkable empirical discovery that DWR estimates are virtually unbiased on most pasture types. Several cases are considered where difficulties may be encountered in using DWR. Provided the theoretical reservations of this paper are borne in mind, DWR will continue to be a useful practical tool, especially in the absence of non-destructive observational alternatives.

Notes: Three groups of cows were continuously stocked on pasture and offered supplementary concentrates according to the herbage height measured weekly with a grass disc. Concentrates were offered when the mean herbage height fell below 9 cm for treatment A, 7 cm for treatment B and 5 cm for treatment C at a rate of 1 kg d-1 for each 0·2-cm decline below these threshold levels. If the herbage height declined by more than 1·2 cm (8 kg concentrates d-1) hay was offered in addition ad libitum. The stocking rates for all three treatments were 5·2, 3·2 and 3·2 cows ha-1 for three successive 8-week periods. For treatments A, B and C the mean concentrate DM intakes were 3·2, 1·2 and 1·2 kg d-1 (treatment A also received 0·2 kg hay DM d-1), and the mean daily milk yields were 17·2, 16·2 and 15·2 kg respectively. The increasing level of supplementary feeding from treatment C to A also resulted in an increase in liveweight and body condition score change, and a reduction in milk fat.

Notes: The effects of sheep grazing on the development of and production from heather swards and on intake and diet selection by grazing Scottish Blackface wether sheep were studied in an experiment in which sheep numbers were adjusted to remove 0, 40% or 80% by weight of current season's shoots in summer and in autumn for a period of 5 years. All combinations of season and level of grazing were provided. The plots were divided after 2 years and grazing was continued for a further 3 years on one subplot but discontinued on the other.Sward productivity during the 5 years of grazing was unaffected at the 40% level of shoot removal but at the 80% level was reduced by up to 66%.After a season's uninterrupted growth at the end of the experiment heather cover and herbage mass were lower and current season's shoots as a proportion of total mass were higher on those treatments which received the greatest severity of grazing. Weight of current season's shoots was unaffected on treatments which had received the 40% level of shoot removal but was reduced by 40% and 50% on treatments which had received the 80% level in summer and autumn respectively. On the rested subplots sward recovery was such that no treatment effects remained after 3 years except with respect to 80% shoot removal in autumn where herbage mass was reduced compared with other treatments.Intakes of digestible organic matter per sheep were higher at the 80% than the 40% level of grazing in the fifth year of the experiment. This was ascribed to the ingestion of new shoot growth from the twig bases on the 80% level of removal treatments. Intake and digestibility were higher in the summer on those treatments which had received the 80% level of removal in previous autumns. Over the 5 years of the experiment there was a small decline in intake and digestibility values, with the decline being greatest in the summer and at low levels of grazing.Floristic changes differed on the rested and grazed areas. On the rested subplots in the fourth year after grazing stopped, heather height was lower and cover by grasses, sedges and herbs was greater on treatments which previously had received the highest levels of utilization. On bare areas the rate of recovery of heather was rapid where shoots as well as seedlings contributed to recovery growth. On the grazed subplots, with the exception of the low-growing ruderal Rumex acetosella, cover due to grasses, sedges and herbs remained low as species other than heather were selectively grazed.Relationships among stocking rates, grazing behaviour and heather utilization are discussed and guidelines for the recognition of overgrazing are outlined.

Notes: In a study of growth rates and developmental morphology of simulated swards of two contrasting white clover varieties, Katrina and Kent, it was found that both varieties continued to produce dry matter throughout the winter at Aberystwyth. The gross crop growth rate in the coldest periods was about 7 kg ha-1 d-1. The rates of formation and loss of new leaves were approximately equal so that there was no net increase in weight until the latter part of March. This initial net weight increase in both varieties was observed in the same harvest interval, the most important factor being the difference in weight between the new leaf plus petiole unit and the weight of the unit which it replaced. The weight of laminae and petioles throughout the experiment was somewhat higher in Katrina which has come to be regarded as the ‘earlier’ variety.The prospects for improving spring production in white clover by variety improvement are discussed.

Notes: A technique for estimating the rate of disappearance of material from samples of dead herbage protected by simple nylon or wire mesh covers is described. Using this technique on a perennial ryegrass sward in southern England during August-November, relative rates of disappearance close to 0·204 g g-1 d-1 (DM) were obtained, but the variability was high. When herbage killed with paraquat was used, the rate of disappearance was higher and the variability lower. There were only small differences in the temperatures recorded in a normal sward and within samples of dead herbage under mesh covers.

Notes: Electrical capacitance and root diameter techniques for estimating root dry weight were evaluated in one test with red clover plants grown on slant-boards in plant growth chambers for 37–77 d, and in six tests with alfalfa grown in the field for 55–165 d. Root dry weights of red clover were estimated satisfactorily with regression equations from both diameter (R2=90%) and capacitance (R2=76%) measurements. Root dry weights of alfalfa were estimated satisfactorily throughout the entire season from diameter values (R2 from 51 to 92%). Alfalfa root weight was significantly (P 〈0·25) related to capacitance values at the beginning and at the end of the season but not at mid-season. Electrical capacitance measurements were similar for intact root systems and roots severed 4 cm below the crown in separate experiments with red clover and with alfalfa. The root diameter technique provided an accurate, rapid and inexpensive method of estimating root size throughout the first season of growth. The root capacitance method provided satisfactory estimates of roots at certain times during the summer. Neither method would be useful if a large portion of the root was naturally severed.

Notes: Italian ryegrass was slot-seeded into permanent grass in two field experiments at Oxford. In the first experiment August and September proved to be the most reliable months for slot-seeding, with April as a possible alternative. A row-spacing experiment showed that the optimum distance between rows was about 30 cm; seed rate in the row had a lesser influence on increasing herbage growth. In both experiments slot-seeding did not result in any substantial change in earliness of growth or alter total herbage harvested but it did even out the seasonal distribution of growth, particularly by increasing it in the following July.

Notes: An apparatus is described which enables excised pieces of plant material lo be weighed al frequent intervals as they dry in controlled conditions of temperature, humidity and air-speed. The effect of removing the epidermis on the drying rate of red clover (Trifolium pratense) leaflets, leaf petioles and stems is examined. Initially this treatment caused a very large increase in the drying rate of leaflets. Although the effect declined as water content fell, leaflets from which the epidermis had been removed still dried more rapidly than the controls at a water content equivalent to 50% of the dry weight. Removing the epidermis had a greater effect on the drying rate of leaf petioles and stems at low water contents than it did on the drying rate of leaflets.Slow drying at low water contents is a major factor responsible for the undesirably long periods for which hay may lie in the field. Slow drying occurs even though swath microclimate becomes more favourable for drying as water content falls. The results presented here suggest that treatments which reduce cuticular resistance have the potential to reduce field drying time.

Notes: A detailed study of the spring growth curves of two forage grasses, tall fescue and cocksfoot, over three successive years showed a large variability of growth over the vegetative phase. This variability was evident at levels of fertilizer N which were considered to be non-limiting (60 kg N ha-1 in autumn plus 120 kg N ha-1 in February).At this level of N there was a relationship between yield in the vegetative phase and accumulated temperatures from the last cut in the autumn which was described by a regression common to the three years. The slope of this regression represents the potential growth of a variety. At a lower level of N a separate regression was needed in each year to relate growth to accumulated temperature.Variation in spring growth was not related to accumulated net radiation. Growth in the reproductive phase was related to accumulated temperature and accumulated net radiation from the 10-cm ear stage.

Notes: In subtropical latitudes temperate crops can be grown during the cool months but the growing season is restricted by the termination and beginning of hot weather. Postponing sowing date in south Florida from October to November to January resulted in 150, 130 and 110-d growing seasons respectively. Dry matter (DM) yields of turnip, swede, rape and kale were lowered by each later sowing date and shorter growing season, and crude protein (CP) concentration was the same as for, or was increased by late sowing. In vitro organic matter digestibility (IVOMD) of turnip, swede and rape leaves was not affected by sowing date, but roots of turnip and swede from the earlier sowings and longer growing seasons were more digestible. Yield of the four species depended on harvest management as well as date of sowing and length of growing season. Total yield of turnip and swede were unaffected by harvest management but multiple cutting resulted in greater leaf yields and smaller root yields, whereas stockpiling resulted in smaller leaf yields and larger root yields. Kale produced more DM when harvested once at the end of the winter growing season but rape produced the greatest DM yield when sown in October and harvested

Notes: Plants of white clover (Trifolium repens L.) cv. Blanca and red clover (T. pratense L.) cv. Hungaropoly were grown singly in controlled environments. The effects of eight treatments on the two species were examined: 16- and 8-h photo-periods × 20/15 and 15/10°C day/night temperatures ×Rhizobium-free plants receiving nitrate N and inoculated plants receiving no combined N. Twice weekly measurements of the main axis leaf size, petiole length, rate of leaf production and the time period between the appearance of a leaf and its final size were carried out for 8 weeks after sowing.Increasing the day/night temperature from 15/10 to 20/15°C, or doubling the daylength from 8 to 16 h (doubling the daylength increased temperature by 1·2°C) accelerated the rate of leaf production and expansion and increased petiole length and the final area of leaves. Most aspects of main axis leaf growth were reduced in the inoculated plants dependent on their own N fixation compared with the nodule-free plants receiving abundant nitrate N. The results suggest that the temperature above which white clover exhibits appreciable leaf growth in the field could be relatively high compared with grasses. Further research is required to define these differences and relate them to seasonal changes in the environment.

Notes: Preharvest application of 1 and 2 litres ha-1 IPA glyphosate (glyphosate) to a seed crop of S24 perennial ryegrass with moisture concentrations of around 400 and 340 g kg-1 (40 and 34% moisture content w/w) failed to significantly lower seed and straw moisture concentration at harvest and consequently did not affect combine rate. Addition of extra surfactants and ammonium sulphate to glyphosate did not significantly increase the rate of desiccation.The quality of harvested seed was impaired at both rates and application times. Germination was significantly lowered through the production of abnormal seedlings. The germination of seed harvested in the previous year from glyphosatetreated plots decreased with storage. Seed vigour, germination rate and field emergence were also significantly decreased as a result of glyphosate application. The effect of glyphosate on seed quality precludes its preharvest use as a desiccant in the ryegrass seed crop.Harvesting difficulties due to the production of secondary vegetative tillers may be overcome by swathing rather than direct combining.

Notes: The fertility of forty-two heifers offered either red clover silage or grass silage prior to and during the period of insemination was compared. Pregnancy rate to first service was significantly higher (P 〈 0·25) on red clover silage at 76% compared with 43% on grass silage. Pregnancy rates from a mating period covering three oestrus cycles were similar on the two silage diets. The ratio of services to pregnancies was lower on red clover silage (1·2) than on grass silage (2·2). In a subsidiary trial with twenty-three heifers, pregnancy rate to first service on red clover silage was 78%.There was no evidence to indicate that herd fertility is depressed by red clover silage.

Notes: An estimate of the level of pest damage on enclosed upland permanent pasture in England and Wales was made by reducing invertebrate populations with insecticides at thirteen well-distributed sites and measuring the effect on herbage growth over a 3-year period. Potential pests were fewer in number than on lowland pastures and there was a wide range in herbage yield between sites. Insecticide treatment significantly increased annual yields at only three of the sites, and significantly decreased yield at two of the sites. Insect damage to grassland appears to be much less important in upland than in lowland areas: this may be due to the relative scarcity of frit-fly in these areas, but this could change if its preferred host, ryegrass, were encouraged by intensification of sward management in the uplands. At all but one of the sites insecticide treatment led to considerable soil compaction, probably as a consequence of suppressing earthworm populations.

Notes: Eight samples of perennial ryegrass-white clover herbage with in vivo dry matter digestibility (DMD) ranging from 0·279 to 0·264 were used to evaluate various cost-saving modifications to the two-stage pepsin–cellulase digestibility technique. The effect of sample size, cellulase quality, cellulase/sample ratio, digestion time and washing of residue following digestion were investigated. The loss of dry matter (DM) in the assay was correlated with in vivo DMD and each variation of the method was evaluated by comparing the s.d. between replicates and r.s.d. of the regression, as well as the convenience of the method for large-scale monitoring of digestibility of mixed ryegrass-clover herbage.It was found that the amount of cellulase used could be reduced by a factor of 25, compared with recently published methods, without increasing s.d. or r.s.d. appreciably. In addition stirring during digestion and washing of the residue could be omitted without any deleterious effects. Increasing digestion time did not reduce s.d. or r.s.d. and the low-grade cellulase proved to be slightly more economical.Increasing the sample size from 0·25 to 0·20 g improved the s.d. and r.s.d. but the residues from the larger samples were generally slower to filter, which made the assay unsuitable for routine use. Substantial reduction of digestion volume and use of a thermostatically controlled water bath instead of an incubator led to a considerable increase in efficiency and throughput of samples. Stirring the samples during digestion was found to be unnecessary, thus allowing more flexibility in the laboratory routine, for example using the weekend for digestion. Using the recommended method modification the repeatability between replicates and r.s.d. of the calibration regression was 0·204 and 0·215 respectively for samples ranging in DMD from 0·279 to 0·264.

Notes: Six varieties of white clover, each grown with perennial ryegrass, four intervals between cuts and two levels of applied nitrogen in all combinations, were compared in a field experiment during the first 27 months after sowing.Increasing the interval between harvests from 3 or 4 to 8–12 weeks increased the yield of white clover and generally did not reduce the proportion of clover in total herbage. Increasing the interval between harvests reduced the number of grass tillers but increased grass yield and the size of grass leaves and increased grass height more than clover height; it also increased the proportion of petiole relative to leaflet in the clover. Differences between varieties in response to interval between harvests were small but supported the view that medium large-leaved varieties can with advantage be defoliated rather less frequently than small-leaved ones. The adverse effect of applied N on clover appeared almost equally great with all four intervals between harvests and further research on this topic is suggested. Applied N increased grass height more than clover height and increased the number of grass tillers, the size of grass leaves and grass yield. The medium large-leaved varieties seemed more tolerant of applied N than the smaller varieties.

Notes: The toxic and mutagenic effects of gamma-irradiated peanut meal contaminated with aflatoxin B1 were studied in Salmonella typhimu-rium strain TM 677, using forward mutation to 8-azaguanine resistance. After treatment with 5 to 10 M-rad gamma radiation, the contaminated peanut meal lost its toxic and mutagenic properties. Irradiation at 0.1 to 1.0 M-rad removed 75–100% of the toxicity but not mutagenicity.

Notes: This paper reports the levels of Pb, Cd, and Zn found in 39 individual canned foods and in samples of ground beef and sugar collected throughout the United States in fiscal years (FYs) 1980 and 1981. The foods were collected in conjunction with the Total Diet Studies program of the Food and Drug Administration (FDA), but were analyzed separately from the Total Diet samples at the FDA Kansas City District Laboratory. Before analysis, multiple-can samples of each product type were individually composited and thoroughly homogenized with dilute nitric acid to ensure representative subsamples for analysis. Homogenized subsamples were dry-ashed with sulfuric acid as the ashing aid and analyzed by differential pulse anodic stripping voltammetry for Pb and Cd and by atomic absorption spectroscopy for Zn. Quantitation limits were 0.02 ppm Pb, 0.002 ppm Cd, and 0.1 ppm Zn. The overall mean levels of Pb, Cd, and Zn found in the 19 canned foods that contained sufficient samples for statistical analysis were 0.19 and 0.22 ppm Pb, 0.011 and 0.008 ppm Cd, and 4.3 and 5.0 ppm Zn in FY-80 and FY-81, respectively. These levels are about one-half as high as the levels found for Pb and Cd in an FDA FY-74 survey but are about the same for Zn. The frequency and magnitude of occasionally high levels of Pb in individual samples were considerably diminished in FY-80 and FY-81, compared to those in FY-74. These lower levels are probably due to improvements in canning technology, in quality control by food processors, and in the methods used for analysis. Over the next 3 years the FDA will continue this survey of individual canned foods, focusing on adult canned foods commonly eated by children, to monitor the progress of industry in reducing Pb levels in canned foods.

Notes: The three major secondary metabolites of Penicillium viridicatum, brevianamide, xanthomegnin, and viomellein were tested for mutagenicity by the Salmonella/microsome test and for toxicity and teratogenicity by the chick embryo test. None were mutagenic. Viomellein was mildly toxic and teratogenic, xanthomegnin was the most toxic and was not a teratogen, and brevianamide was not toxic yet was the most teratogenic.

Notes: Poly (hexamethylene biguanide hydrochloride) (PHMB), an industrial disinfectant, was evaluated for potential use in the food industry following suggestions in the literature. A colorimetric test based on the reaction with nitro-prusside reagent was found suitable for the dosimetry of this compound. In a bacteriological medium, at a concentration of 20 μg/ml, PHMB was inhibitory to Escherichia coli, less effective against Staphylococcus aureus, and practically ineffective against Pseudomonas aeruginosa. The bactericidal activity of PHMB was impaired in the presence of milk but little affected upon the addition of blood. Finally, in a toxicological test in vitro, PHMB was found to be toxic toward Chinese hamster cells, at doses similar to those required for antibacterial activity.

Notes: The results obtained by a rapid Celite column extraction method for the determination of dimethylnitrosamine (DMN) in beer and ale were compared with those obtained by a more elaborate vacuum distillation method. The end determination in both cases was done by gas-liquid chromatography using a thermal energy analyzer (TEA) detector. The two sets of results for 28 samples of beers from various countries were highly comparable. Recent survey results for both Canadian and imported beer and ales suggest a significant decrease in the levels of DMN in these beverages from that observed 2–3 years earlier. This decrease is probably due to the improvements in the malt drying techniques instituted in Canada as well as in other countries.

Notes: In separate experiments, growing and/or finishing swine were fed a control diet and diets supplemented with various low levels of lead and cadmium, for periods up to 24 weeks. The levels of lead in different treatment groups were 2 (control), 6 and 21 parts per million (ppm), whereas those for cadmium were 0.2 (control), 2.4 and 10.1 ppm, respectively. Lead did not accumulate in skeletal muscles, but a dose-related increase was observed in bone, liver and kidney. In the case of cadmium, no increase was seen in skeletal muscles, bone or brain; the accumulation occurred primarily in kidney and liver. After cessation of lead supplementation the concentration of this metal declined in liver and kidney tissues. On the other hand, cadmium levels did not show any appreciable decline in kidney or liver during 12 weeks after an initial 12 weeks treatment. Lead and cadmium did not accumulate in edible muscles of swine, but the high concentrations of these metals that were recorded in liver and kidney would render these organs unfit for food purposes.

Notes: Aerobic plate counts on Plate Count Agar at 25°C were used to determine the time required to reach a microbial spoilage level of 1.0 × 107 C.F.U./g, for mechanically deboned chicken meat, minced fish and chicken sausage stored at 2°C. The storage times were 5, 8 and 9 days, respectively. Addition of citric acid (0.2%), ascorbic acid (0.2%) or lauricidin (250 ppm) alone extended the shelf-life by 0–2 days. The combination of lauricidin and citric acid or lauricidin and ascorbic acid extended the time required to reach a microbial spoilage level for mechanically deboned chicken meat by as much as 7 days, minced fish by as much 4 days and chicken sausage by 8 days.

Notes: A depuration chamber was used to study the persistence of marine vibrios in the hardshell clam, Mercenaria mercenaria. Specimens of M. mercenaria were incubated for two h in artificial seawater containing 103 cells/ml each of the following bacterial species; Vibrio parahaemolyticus, Vibrio harveyi and Escherichia coli, and then transferred to the depuration chamber (a tank through which U. V.-sterilized artificial seawater was continually flowing). Numbers of the three bacterial species in tissues of M. mercenaira removed from the chamber at various times were determined by differential plating techniques. The number of each species ranged from 102 to 103 colony-forming units/gram tissues immediately after transfer to the depuration chamber. After 24 h at 25°C the number of E coli cells detected had decreased over 100-fold. Generally, V. parahaemolyticus and V. harveyi were found in increased abundance after 24 h. The abundance of V. parahaemolyticus and V. harveyi in clams that had been incubated in the depuration chamber for 72 h at 25°C was approximately 10% of the abundance of these species immediately after transfer to the chamber. Similar results were obtained when the incubation temperature was 8 or 15°C and when initial cell concentrations were altered. Thus, V. harveyi and the potential human pathogen, V. parahaemolyticus which are both of marine origin were not removed from M. mercenaria at a rate comparable to the rate at which M. mercenaria depurated cells of E. coli.

Notes: Results are presented for a limited survey performed in 1978 for residues of ethylenebisdithiocarbamate (EBDC) fungicides and ethylenethiourea (ETU) in raw and canned spinach and tomato samples (12 samples each of the raw and 12 each of the canned commodities). Correlated samples of each commodity were obtained by batch sampling the canned commodity and the corresponding raw commodity. Most of the tomato sample analyses were negative for EBDC and ETU. However, the 12 raw, unwashed spinach samples contained relatively high levels of EBDC residues (5.2 — 80 ppm calculated as zineb) and 0.12 — 2.3 ppm ETU; the ETU residue levels were somewhat proportional to the EBDC residue levels. It appears that washing the spinach before canning removes the EBDC residues, but not the ETU residues. Cooking the raw spinach samples in the laboratory to yield “cooked” or “total” ETU was found to be useful for identification and semiquantitative confirmation of EBDC residues. There was considerable variation between replicate ETU determinations for each spinach sample.

Notes: The influence of pH on the susceptibility of Staphylococcus aureus 196E to repeated freeze-thaw stress was studied in 0.2 Macetate buffer (pH 3.0–7.8) and ground beef (adjusted to pH 4.2–6.3). In acetate buffer in the pH range of 4.4–7.0, repeated freeze-thaw stress did not decrease the viability of the cells; at pH values below 4.1 and above 7.5, decrease in the viable cells was exponential with the number of freeze-thaw cycles. In meat, S. aureus was not killed at pH values 4.3–6.3; however, at pH 4.2, death resulted from the repeated stress. Repeated freeze-thaw cycling of foods should have little effect on the viability of S. aureus within the pH values of most foods implicated in S. aureus food poisoning.

Notes: A desmutagenic factor which inhibited the mutagenicity of the mutagens, Trp-P-1 (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole), Trp-P-2 (3-amino-1-methyl)-5H-pyrido[4,3-b]indole), ethidiumbromide and 2-aminoanthracene, was purified from broccoli (Brassica olerancea var. italica plenck). The factor was not sedimented by ultra-centrifugation at 200,000 xg for 2 h. It adsorbed to a DEAE-cellulose column and was eluted with low concentration of potassium chloride. The purified factor exhibited a heme-like protein absorption spectrum with a Soret band at 403 nm and α and β bands at 640 and 504 nm, respectively. The molecualr weight was estimated to be approximately 53,000 by SDS-gel electrophoresis.

Notes: Modified Skirrow's (with 15 μg cephalothin/ml), Campy-BAP, and Butzler's selective agar plates were compared for sensitivity and selectivity in the recovery of inoculated Campylobacter fetus ssp. jejuni from ground beef. The diluted inoculation samples were surface plated directly onto these selective plates and incubated. When colonies on the plates were enumerated, characterized, and identified, Campy-BAP medium proved to be the most sensitive for recovery, and Butzler's medium the most selective. Contaminants of Pseudomonas and Acinetobacter were observed. A combination of both Campy-BAP and Butzler's media should prove most useful in the recovery of Campylobacter from food sources. The significance of current taxo-nomical considerations for food microbiologists are also discussed.

Notes: The widespread use of caffeine is most commonly linked to the stimulatory action it has on the central nervous system. Generally, adverse effects include gastrorrhea, insomnia, and diuresis. Tolerance and withdrawal symptoms have been observed and excessive consumption can lead to an anxiety neurosis condition (caffeinism). The actions of caffeine may involve its effects on neurotransmitter turnover and metabolism; its promotion of the cellular messenger, cAMP; its sensitization of the calcium releasing mechanisms of cellular reticulum; or its antagonism of the autacoid, adenosine. Caffeine lethality is rare in man but caffeine poisoning with its gastrointestinal, CNS, and cardiovascular stimulation could especially be hazardous to children. Most of the mutagenicity work has been performed in organisms whose cellular DNA synthesis and repair mechanism vary significantly from those found in man. The work in human cell lines suggests that caffeine-induced chromosomal breakage, with its lack of chromatid exchange would promote cell lethality, not muta-genticity. Nothing but circumstantial evidence implicates caffeine as a human carcinogen or teratogen. Involvement of caffeine as a cocarcinogen or a coteratogen (which includes effects on gamete production or fetal development) appears far more likely, but neither has even begun to be truly evaluated. Basic metabolism of caffeine involves the processes of N-demethylation, hydration, and oxidation; and most likely requires the cytochrome P1-450 system. Though various metabolites of caffeine are pharmacologically active, the extent of involvement of individual metabolites in the pharmacological or toxicological responses of caffeine in man is still unknown.

Notes: Monolaurin alone and monolaurin with tert-butylhydroxyanisole (BHA), methylparaben, or sorbic acid were tested for in vitro virucidal activity against 14 human RNA and DNA enveloped viruses in cell culture. At concentrations of 1% additive in the reaction mixture for 1 h at 23°C, all viruses were reduced in infectivity by 〉99.9%. Monolaurin with BHA was the most effective virucidal agent in that it removed all measurable infectivity from all of the viruses tested. The compounds acted similarly on all the viruses and reduced infectivity by disintegrating the virus envelope.

Notes: LauricidinR (monolaurin) and related compounds were tested against 16 fungi belonging to different groups and having different cell wall composition. Lauricidin Plus F (a combination of monolaurin, butylated hydroxy anisole and ethylenediaminetetraacetic acid) was the most effective agent and inhibited the growth of all fungi tested at a concentration of 0.1%. Lauribic (a combination of monolaurin and sorbic acid) also exhibited strong antifungal activity but was less effective than Lauricidin Plus F. In most cases Lauricidin showed antifungal activity at a concentration of 0.5%. Other commercial samples of monolaurin, e.g. Lauricidin 812 (A), Lauricidin 802 (B), and Lauricidin 112 (C), showed higher antifungal activity than Lauricidin. Tests comparing Lauricidin Plus F with sorbic acid, K sorbate and propionic acid, showed that Lauricidin Plus F has higher antifungal activity except when sclerotia of Sclerotium rolfsii were used for inoculation. Lauricidin Plus F was fungistatic and maintained its activity in a semi-synthetic medium for at least 21 days at 26°C.

Notes: Laboratory studies on the degradation of several sugar-beet herbicides both singly and in combination with lenacil were conducted in four soils. First-order kinetics were used to describe the breakdown rates of lenacil, benzthiazuron, carbetamide, propham and phenmedipham, and their combinations with lenacil. Mean half-lives of the herbicides ranged from 14 days for propham to 191 days for benzthiazuron. There were no significant differences between the herbicides applied singly or in combination.Persistance dans le sol de plusieurs herbicides de la betterave et leurs combinaisons avec le lenacilPour quatre types de sols, nous avons étudié, au laboratoire, la dégradation de plusieurs herbicides de la betterave appliqués seuls ou avec du lenacil. Des cinétiques de première ordre ont été utilisées pour calculer les taux de dégradation des herbicides suivants: lenacil, benzthiazuron, carbetamide, prophame, phenmediphame et de leurs combinaisons avec du lenacil. Les temps moyens de rémanence des herbicides se situaient entre 14 jours pour le prophame et 191 pour le benzthiazuron. Nous n'avons trouvé aucune difference significative entre les herbicides appliqués seuls et avec du lenacil.

Notes: Dans une population de folles avoines de l'Italie centrale, l'observation des caractéres diagnostiques a permis de reconnaitre l'existence de deux espéces, Avena fatua et Avena sterils, cette dernière représentée par deux sous espèces: A. Iludoviciana et A. macrocarpa. Ces différentes entités sont présentes dans des proportions trés différentes. De plus, il existe des individus difficiles à classifier. l'étude de caractères biochimiques: electrophorèse d'enzymes foliaires (estérases, peroxydases, GOT) et le traitement de ces données par une analyse factorielle des correspondances ont montré l'existence des mèmes groupes; cependant A. fatua est plus proche de A. ludoviciana que celle-ci de A. macrocarpa. Entin les individus particuliers semblent, par leur position intermédiaire, descendre d'hybrides naturels entre les deux espèces.

Notes: Eupatorium adenophorum Spreng. is an important weedy colonizer in early successional communities developing after slash and burn agriculture (jhum) at higher elevations of the north-eastern hill regions of India. The relative performance of this species in terms of fecundity and survivorship in successional plant communities has been worked out. A net population increase occurred through both vegetative and sexual reproduction in early successional fallows up to 6 years old, the increase being greatest in a 6-year fallow. Mortality of seedlings was high in 1- and 3-year fallows, low in a 6-year fallow but reached 100% in older fallows. Seedling mortality was maximal during the monsoon although some seedlings also died during winter as a result of drought and frost. Mortality of vegetative sprouts followed a similar pattern to that of seedlings. The reproductive potential was reduced with increasing age of the successional communities and in a 15-year fallow all individuals were non-reproductive. Since E. adenophorum is able to succeed only in fallows of less than 6 years, repeated short jhum cycles of 4–5 years have had the effect of arresting succession al the weedy stage.