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: Over a 3-year period the productivity of perennial ryegrass (Lolium perenne L., cv. S24) swards as influenced by variations in the time of initial defoliation and close (2·5 cm) and lax (8 cm) defoliation was studied. Treatments with initial defoliations in the early vegetative stage, stem elongation and flowering stages of growth gave higher annual yields than treatments in which the initial defoliation was taken at an intermediate stage of growth when the majority of the stem apices had just been elevated above the height of defoliation. Initial defoliation treatments which removed a high proportion of apical meristems while the yield at the initial defoliation was still low produced the lowest annual yield. Consistent lax defoliation reduced yield by 14·5% compared with continual close defoliation. However, taking an initial lax defoliation followed by subsequent close defoliations produced a slight yield advantage of 4·8% over consistent close defoliation. The results are discussed in relation to other research findings and the practical implications commented upon.

Notes: Estimates of the total acidity of silage effluent from a range of first-cut silages varied from 1025 to 21,125 mg Ca CO3 per l with a weighted mean of 8817 mg l-1. Quick-lime (CaO), hydrated lime [Ca(OH)2] or caustic soda (NaOH) were found to be effective neutralizing agents when thoroughly mixed with the effluent. Results from seven field-plot experiments carried out between 1973 and 1977 involving application of silage effluent to grass swards are reported. Leaf scorch occurred when silage effluent with a total acidity equivalent to more than 6000 mg CaCO3 per l was applied at rates exceeding 50 m3 ha-1 to swards with several weeks regrowth. Scorch was most severe when applications were made during periods of dry sunny weather and to mechanically damaged swards. In these conditions reducing the total acidity to below 2000 mg CaCO3 per l by neutralization or dilution allowed rates of over 100 m3 ha-1 to be applied without harmful effects.Acid neutralization was found to be unnecessary when silage effluent was applied to recently cut swards. Here rates of up to 150 m3 ha-1 were applied without adverse effects and generally resulted in increased grass growth.

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: Replicated plots of Hungaropoly red clover were sown on a sterilized area in May 1975 alone (seed rate 11 kg ha-1) or with one of six cultivars of perennial ryegrass (seed rate 3·5 kg ha-1) viz. Cropper and S24 (early heading), Barlenna and Hora (medium heading) and Melle and Perma (late heading). In 1976 and 1977 primary growth was cut at one of four dates ranging from mid-May to mid-June and thereafter plots were harvested twice each year.Varying the time of first cut did not have a significant effect on total dry matter (DM) yield in either year despite differences in means of cutting treatments on annual red clover yields of the order of 6–9%.In some companion grass treatments total DM yield in 1976 was increased and total red clover yield and percentage red clover contribution were reduced relative to swards sown only with red clover. In 1977 a similar but non-significant trend was found. Swards containing early ryegrasses had higher total herbage DM yields but lower red clover yields and contents than all other swards at the first harvest in both years.Delay in date of taking the first harvest in 1976 reduced DM digestibility in the first cut and increased it in the second in both years.It is suggested that by cutting early and increasing the number of harvests from three to four per year, differences in the content of red clover between the first and second cut might be reduced, and it is concluded that more benefit is derived from red clover when medium or late heading ryegrasses are used as companion grasses.

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: Results of experiments where timothy, perennial ryegrass and mixtures of these two in the presence and absence of white clover and receiving various nitrogen treatments were compared, have been considered in the light of previous related experiments. There is evidence that under certain conditions greater yields of sown grass can be achieved from mixed seedings than from either of the two grasses on its own. No yield advantage was gained from mixtures of species when cut infrequently after a late first cut. Inclusion of white clover changed the balance of species in favour of perennial ryegrass and no yield advantage occurred with mixtures in the presence of clover. Yield advantage may be related to seasonal changes in the order of dominance of the two grass species in mixed seedings.

Notes: The lignin and total hemicellulose concentrations of ten varieties of temperate grasses (five species) were determined with increasing maturity. A strong correlation existed between the lignin and hemicellulose concentrations. Lignin and hemicellulose concentrations tended to be higher in cocksfoot and timothy than in perennial ryegrass and diploid varieties also had higher lignin and hemicellulose concentrations than their tetraploid counterparts. The hemicellulose fractions were further separated into their linear and branched components whose compositions were determined. The varieties with higher lignin concentrations showed a higher linear:branched ratio and the ‘linear’ components also had higher xylose: arabinose ratios. These findings were consistent for both leaf and stem tissue although the effects from stem tissue were more marked.

Notes: Nitrogen fertilizer was applied at 0, 30,60 and 90 kg N ha-1 in March 1976, 1977 and 1978 to plots containing perennial ryegrass cv. Barlenna sown either alone or with white clover cv. Blanca, Sabeda, Olwen and S100 in four replicated blocks.Dry matter (DM) yield of all swards responded positively to N with the response being highest in the no-clover swards in two of the three years. Annual DM yields were lower in the no-clover than in the mixed swards at any given N level. The higher levels of N reduced DM yield in mixed swards at some harvests in midsummer.Swards of S100 were consistently among the lower yielding mixed swards, whereas the other three clover cultivars varied in their relative yields. There were no N x cultivar interactions for white clover yields; irrespective of cultivar, N application reduced annual white clover yield by similar amounts.It is concluded that it is beneficial to apply moderate amounts of N fertilizer to mixed swards in spring and that under these conditions the yield differences between swards including medium-large and smaller leaved white clover cultivars are similar to differences between the inherent yield potential of these cultivars in mixed swards receiving no N.

Notes: In order to assess the relative effects of protein content and acid on intake, grass silage was given ad libitum to twelve entire male calves, initially 4 months of age and 117 kg liveweight (LW), either alone or supplemented with fishmeal at 50 g dry matter (DM) per kg silage DM. These two diets were offered alone or with additions of lactic acid at 50 g per kg silage DM in a partial changeover design in which lactic acid levels only were reversed between two 28-d measurement periods.In the absence of lactic acid, fishmeal significantly increased absolute intake but not intake relative to LW. There was a significant interaction between treatments in that the addition of lactic acid depressed DM intake in the absence of fishmeal (23·9 vs 21·1 g kg-1 LW) but not in its presence (23·2 vs 23·1 g kg-1 LW). Addition of fishmeal increased the digestibility of DM from a mean of 0·708 to 0·744 (P 〈 0·05), of gross energy from 0·646 to 0·694 (P 〈 0·01) and of N from 0·422 to 0·592 (P 〈 0·001) but had no significant effect on the digestibility of cellulose (0·766 vs 0·788 for treatments without and with fishmeal respectively). Lactic acid addition had no effect on the digestibility of plant components and, further, interaction effects between treatments were not significant. Supplementation with fishmeal reduced the total time spent eating and ruminating (Ro value) from a mean of 284 to 240 min kg-1 DM (P 〈 0·01) and increased urine pH from 8·34 to 8·50. Lactic acid influenced neither Ro value nor urine pH and the interaction effect did not reach significance for these two parameters.The results indicate that the addition of fishmeal can overcome a depressant effect of lactic acid on intake and it is suggested that the responses to treatment were mediated via changes in the ratio of energy to protein supply rather than as a result of treatment effects on digestive efficiency or acid-base balance.

Notes: Between 1976 and 1978 a further 154 beef animals were grazed in separate groups on Alberts and Far field at Begbroke Hill, the former being a paddock system and the latter being set-stocked. Each year part of Alberts received complete fertilizer (147–180 kg ha-1 N) and part did not. All of Far field received complete fertilizer (140–190 kg ha-1 N). Drought caused a reduction in output in 1976, but in 1977 and 1978 total production of live weight was 9·07 and 8·74 t respectively from 11·65 ha grassland. Calculations of corrected outputs show that maxima of 829 kg ha-1 in Alberts and 908 kg ha-1 in Far field were achieved from fertilized grass. The highest output in Alberts represented 929 livestock unit grazing days per ha or 87·9 GJ ha-1 in 1978.

Notes: Two early perennial ryegrass varieties (Cropper and RvP Hay Pasture), an intermediate perennial ryegrass (Talbot) and an early cocksfoot (Roskilde) were grazed fortnightly by sheep, mown to simulate grazing or left undefoliated from January to May. The effects of spring management on ear emergence, D-value (in vitro) and conservation yields were assessed in each of the 2 years 1976 and 1977. Grazing and mowing had a similar effect on date of first (5%) and 50% ear emergence of the ryegrass varieties; the effect was an average delay of 2 d in both stages of growth over the 2 years. Defoliations significantly (P〈0·001) delayed the fall in D-value with no significant differences between grazing and mowing in the ryegrass varieties, nor in cocksfoot in 1977. The occurrence of a D-value of 67 was delayed by between 3 and 8 d for the ryegrasses and 9 and 11 d for the cocksfoot. The early ryegrasses produced stemmy regrowths and fell to 67 D-value about 4 weeks after the final defoliations in 1976 and after 5–6 weeks in 1977. The fall in D-value took 7–14 d longer in the intermediate ryegrass. Yields were significantly (P 〈 0·001) reduced by grazing and mowing, particularly in 1976. The DM yield reductions in mid June averaged 25% for the ryegrasses and 41% for the cocksfoot.The results indicate that either first or 50% ear emergence may be used to indicate times when a D-value of 67 will be reached in grazed or ungrazed swards but further work is required to determine the effect of weather conditions on the accuracy of this prediction. An early fall in D-value of early perennials after spring grazing, and a marked reduction in yield of cocksfoot, suggests that these grasses should be used sparingly where spring grazing of fields set aside for conservation is a feature of the farming system.

Notes: Paraquat and glyphosate were sprayed on to simulated swards in a glasshouse experiment. Residues of these herbicides depressed emergence, growth and survival of Lolium perenne seedlings sown after spraying.Residues of paraquat applied at a rate (1·5 kg ha-1) within the range normally used for sward destruction killed nearly all seedlings of a normal L. perenne variety, Barlenna, but had much less effect on the paraquat-tolerant variety, Causeway. It was estimated that Causeway was almost nine times as tolerant of paraquat residues as Barlenna. Sowing at a depth of 20 mm gave some protection against paraquat residues. A delay of 10 d between spraying and sowing had equivocal effects. It was concluded that residues of paraquat used for killing swards before direct drilling may hinder the establishment of normal L. perenne varieties but not of paraquat-tolerant varieties.Residues of glyphosate had equal effects on the two varieties and the effects were severest on seedlings sown on the soil surface immediately after spraying. It is thought to be unlikely that glyphosate residues in sprayed herbage would be a problem in direct drilling.

Notes: Small-plot trials with Lupinus albus cv. Kievskij Mutant (sweet) and L. angustifolius cv. Kubesa (bitter) and Uniwhite (sweet) were sown in April 1977. Sequential whole-crop samples of the above ground dry matter (DM) were taken to assess the interaction of DM yield and forage quality during crop growth. Both species had similar DM yields, exceeding 11 t DM ha1 in August. L. albus displayed superior whole-crop in vitro digestibility from late July, due to the large contribution to total DM yield from this time from its succulent, highly digestible pod shells. L. angustifolius showed higher N contents in June and early July, but N concentrations fell below those of L. albus from early August. The steady decline in digestibility of forage from L. angustifolius suggests this species should be harvested rather earlier than L. albus. Harvested in mid-August, L. albus should yield 11 t DM ha-1, ata D-value of 64 and 23·5 g N per kg DM, whereas L. angustifolius harvested 10–14 d earlier should give the same DM yield, but at a D-value of 58 and 22·0 g N per kg DM. Lupins can thus be regarded as having good potential forage yields, but providing material of only moderate quality.

Notes: Book review in this article Turfgrass Management By A. J. Turgeon; illustrated by F. A. Giles Feeding Strategy for the High Yielding Dairy Cow Edited by W. H. Broster and H. Swan Seed production Proceedings of the 28th Easter School in Agricultural Science, University of Nottingham, 1978 Edited by P. D. Hebblethwaite

Notes: Dactylis glomerata and Holcus lanatus were grown together in boxes with either full competition, root competition only, shoot competition only or no competition between them. The boxes were either fertilized (150 kg ha-1N, 100 kg ha-1 K, 80 kg ha-1 P) or not fertilized. The experiment was continued for 13 months, and a total of six cuts were taken. H. lanatus was more competitive than D. glomerata throughout the experiment, though the effect declined after flowering during the second growing season. The effects of root competition were generally much greater than those of shoot competition and tended to increase during the first year. However, the effects of root competition declined, relative to shoot competition, after flowering in the second growing season.Fertilizer applications slightly increased the root competitive ability of H. lanatus relative to D. glomerata but slightly reduced its shoot competitive ability.

Notes: Several different techniques for the non-destructive estimation of pasture or range biomass are critically reviewed and compared to remote sensing methods. Similarities and differences between the visual estimation procedure, β-attentuation, capacitance meters, weighted disc, and spectral methods are discussed in terms of accuracy, time, ease of operation, operational constraints and calibration procedures. No one technique has been shown to be superior across the board to the other techniques reviewed for ground-based biomass estimation. A discussion of the strengths and weaknesses of each non-destructive method allows for the selection of the technique most suited to a particular application.

Notes: A comparison was made of the effect of a cereal supplement during early lactation on the performance and intake of ewes suckling two lambs while rotationally grazing pasture at stocking rates of 20, 17 or 14 ewes per ha. Supplement (S) at the high (H) and medium (M) stocking rates resulted in higher organic matter (OM) intakes (grass + supplement) of 2040 and 2500 g d-1 respectively, compared with the herbage OM intakes of unsupplemented (U) ewes of 1750 and 2040 g d-1 respectively. At the low (L) stocking rate the total OM intake of supplemented ewes and the herbage OM intake of unsupplemented ewes was similar at 2250 and 2210 g d-1 respectively.Lamb growth rate (g d-1) to 12 weeks of age was significantly lower on treatment UH (229) compared with those on UM (253) and UL (262). Growth rates on S treatments were similar (SH 248; SM 261; SL 272) and there were no significant differences between S and U within stocking rates. Unsupplemented ewes lost significantly more weight during the period of intake measurement than those receiving supplement. The speed of rotation was faster where supplement was not fed at the medium and high stocking rates and herbage accumulation under UH was less than under SH. Only at the high stocking rate did feeding a supplement give a higher financial output.

Notes: Calibration of an earth-plate forage capacitance meter was conducted on pure stands of Festuca arundinacea Schreb., Medicago sativa L., Cynodon dactylon (L.) Pers. and Trifolium repens L. and a mixture of Trifolium repens and Dactylis glomerata L. Dry weight (DW) prediction equations were developed using the instrument capacitance reading modified by visual estimates of height, stand density and species percentage. In general, meter readings (MR) correlated better with DW than with fresh weight or weight of water and especially when the area harvested exceeded 0·537 m2. Correlation between MR and DW improved with increasing top plate area and with decreasing distance between the top plate (suspended sheet of aluminium) and the earth-plate ground. The use of a plastic shield to suppress the forage to a uniform height caused a reduction in the correlation between MR and DW.The use of MR to predict DW from selected settings, their linear and curvilinear relationships and several auxiliary observations gave results with R2 values ranging from 0·94 to 0·99, depending on species and mixture.

Notes: The response of marsh birdsfoot trefoil (Lotus uliginosus) to inoculation with appropriate Rhizobium spp. was compared over 2 years. Inoculated and uninoculated seed was sown at 5 kg ha-1 on three soil types, brown earth, peaty podsol and deep peat. Perennial ryegrass cv. Perma was sown at 20 kg ha-1 as a companion species. Plots received either no N or a light starter dressing of 30 kg ha-1 N. Significant benefits from inoculation were recorded for Lotus germination and nodulation, Lotus and non-Lotus herbage DM harvested and Lotus cover on the deep peat, and to a lesser extent on the other soil-types. Due to particularly uneven early establishment, work on the peaty-podsol site was discontinued at an early stage. There was a trend towards depression of Lotus where N had been applied to inoculated plots.

Notes: The effects of fertilizer treatment were studied over two seasons on a 2 × 2 factorial arrangement of altitude and major soil group. The soil groups were brown earths and podzols and the altitudinal zones were 260–320 m and 380–440 m. Major responses were found to N only and these were generally linear in terms of overall dry matter yield up to the highest treatment level of 176 kg ha-1. Productivity on brown earths was significantly higher than on podzols and differences between soil groups were not removed by increasing fertilizer input. In most instances 88–132 kg ha-1 N would have to be added to podzols to achieve the same yields as on brown earths with no N input. Apparent fertilizer recoveries and responses per unit of fertilizer input did not, however, differ markedly between soil groups. Overall yields were comparable with those from lowland situations at similar levels of N input, but the growing season was short and 60–80% of production was obtained by early July.

Notes: Plants of Holcus lanatus L. and Lolium perenne L. were grown in monocultures and in 50:50 mixtures and cut at three heights and at three frequencies during 24 weeks. The higher the H. lanatus plants were cut the greater was their harvested yield but height of cutting did not affect the yield of L. perenne. Reduction in the frequency of cutting increased the total harvested yield of both species in monoculture. In mixture, H. lanatus dominated L. perenne, especially with high and infrequent cutting. Stubble yields generally followed harvested yields.In a second experiment, H. lanatus plants were cut sequentially in spring; plants cut in early June produced very few panicles in the regrowth.In a third experiment the growth of decumbent tillers in late summer on spaced plants of H. lanatus produced a stoloniferous growth habit. The production of lateral shoots and roots on these stolons was measured in spring on plants undergoing various types of defoliation. Regular cutting of the parent plant increased the production of lateral shoots on stolons but did not affect the production of lateral roots.The significance of these results is discussed in relation to the manipulation of swards containing these two species.

Notes: Three first-harvest grass silages made from S23 perennial ryegrass cut on 25 May, 13 June and 25 June, and termed early, medium and late silages respectively, were compared in a 16-week feeding experiment with fourteen Ayrshire cows. The early, medium and late silages had D-values of 71·2, 65·0 and 62·5 respectively. The early silage was offered alone, whereas the medium and late silages were supplemented with a concentrate containing 208 g crude protein per kg DM at rates of 2, 3 and 4 kg per 10 kg milk. Silage DM intake was 12·8 kg per cow per d on the early silage treatment, and decreased progressively as concentrate intake increased on the other silage treatments. The mean daily milk yields were 16·0 kg per cow in the early silage treatment, 17·0, 18·4 and 20·4 kg per cow in the medium silage treatments, and 16·8, 18·1 and 20·2 kg per cow in the late silage treatments on the 2-, 3- and 4-kg concentrate treatments respectively. Fat concentration in the milk was not affected significantly by treatment, whereas the CP and SNF concentrations increased progressively and significantly as supplementary feeding increased. From the relationship between milk yield and concentrate intake it was calculated that the medium and late silages required a daily concentrate supplement of 2·1 kg DM per cow to give the same daily milk yields as the early silage.

Notes: Applications of either sewage sludge or N as ammonium nitrate were made to a 15-year-old hayfield over a 2-year period. The original seeding mixture was unknown but was believed to be timothy (Phleum pratense L.) and red clover (Trifolium pratense L.). During the second year, botanical separations indicated that applications of both N and sewage sludge resulted in reduced proportions of red and volunteer white clover (Trifolium repens L.) as well as volunteer Kentucky bluegrass (Poa pratensis L.). During the growing season a decline in proportion of timothy (Phleum pratense L.) was observed for the control as well as for the N and sludge treatments. In contrast, quackgrass (Agropyron repens (L.) Beauv.) was markedly stimulated by the treatments and the proportion of it in the hay increased during the growing season.

Notes: Italian ryegrass, Lolium multiflorum Lam., cv. RvP., was broadcast in spring on to fine and coarse seedbeds at seed rates of either 2 or 20 kg ha-1. Each of the four combinations of sowing condition was either left untreated or treated with fungicide or insecticide. The establishment of the sown species and of weeds under each regime was measured and their relative contribution to dry matter assessed in four cuts during the sowing year. Seed rate affected weed invasion and yield more than seedbed condition. Insecticide treatment increased the establishment and yield of ryegrass and its contribution to total herbage yield under all four sowing conditions. The fungicide treatment had no effect. The improvements caused by insecticide treatment were associated with a reduction in the level of infestation by shoot flies, Oscinella spp. (Diptera: Chloropidae): the effect of a single treatment in April was still detectable in October.

Notes: Book review in this article The Response of Perennial Ryegrass to Fertilizer Nitrogen in Relation to Climate and Soil Report of the Joint ADAS/GRI Grassland Manuring Trial—GM20 Technical Report No. 27, Grassland Research Institute By J. Morrison, M. V. Jackson and P. E. Sparrow Recognition and Control of Pests and Diseases of Farm Crops (2nd edition) By Ernst Gram An Introduction to Practical Animal Breeding By Clive Dalton Planned Beef Production By David Allen

Notes: An improved electronic capacitance pasture meter is described, and data on its calibration and use in a grazing trial are presented. The instrument is light (1·4 kg) and portable, and uses integrated circuits to record the readings from a number of sampled sites. It has a digital display and can be constructed for a modest cost. The meter is mainly responsive to the surface area of the herbage and hence it is less sensitive to variations in moisture content of the pasture than previous meters. Thus it can be calibrated to measure the mass of herbage dry matter to ground level and reduces the need to collect and dry herbage samples for frequent recalibration of the instrument.

Notes: A forage capacitance-measuring scheme is presented which uses the earth and plants growing in it as one plate of a two-plate capacitor. Low frequency analogue circuitry is coupled with digital circuitry to sense and read out digitally the capacitance as a function of the forage under the sensing head. The circuitry is linear, reasonably stable and offers the opportunity for electrically confining the sensed area. The apparatus behaviour is characterized by a mathematical describing function.

Notes: Dactylis glomerata and Lolium perenne were grown in single-species stands and in mixed-species stands in boxes for 1 year. Plants were grown in paired rows in each box with full competition below ground, but aerial partitions prevented shoot competition. The rows were cut either frequently (six cuts) or infrequently (three cuts).In single-species stands, frequent defoliation reduced the root competitive ability of D. glomerata plants, when growing with infrequently defoliated plants, though this occurred only if no N fertilizer was applied. Frequent defoliation did not affect the root competitive ability of L. perenne plants, in single-species stands, whether or not N fertilizer was applied.In mixed-species stands, the root competitive ability of D. glomerata was always greater than that of L. perenne, though N fertilizer applications and frequent cutting both reduced the root competitive ability of D. glomerata relative to L. perenne.Mixtures of frequently cut and infrequently cut plants, in unfertilized single-species stands, always yielded more than the mean of the uniformly treated stands (frequently or infrequently cut); they usually yielded more than the highest-yielding uniformly treated stand. Mixtures of frequently and infrequently cut plants, in fertilized single-species stands, always yielded less than the mean of uniformly treated stands.Mixed-species stands usually yielded more than the mean yield of the component species, and sometimes yielded significantly more than the highest yielding component. This effect generally increased with time.Relative yield totals (RYT) were consistently greater than 1·0, in both single-species and mixed-species stands, when no N fertilizer was applied. RYT were greatest (1·2–1·6) when neither N nor P fertilizer was applied, and generally increased with time.The results are discussed in relation to the effects of cutting on root competition and the probable value of mixed-species stands.

Notes: Sites were established on good quality grass swards in areas representative of three of the most extensive soil parent materials in north-east Scotland and covering an altitudinal range of 260–460 m. Overall yields of herbage dry matter in 1975 were high, ranging from 6280 kg ha-1 with no fertilizer to 9190 kg ha-1 with an application of 100, 26 and 50 kg ha-1 N, P and K respectively. Differences in production between parent material and altitude groupings were found to be associated with differences in major soils group and past land use, with long-enclosed brown earths outyielding podzols recently reclaimed from heather moorland by about 30% overall. Increasing inputs of fertilizer appeared to reduce the effects of soil and climatic conditions. Brown earths showed higher apparent recoveries of N fertilizer than did podzols.

Notes: Six groups of five 18-month-old wether sheep received a diet of dried grass ad libitum with a pelleted ground barley/oat supplement containing various levels of salt for 30 d. The first group received grass of high Na concentration (7·3 g per kg DM) with no added salt in the supplement, a second group received low sodium grass (4·2 g per kg DM) with no salt additions, and the other four groups received the low sodium grass with varying levels of salt added to the supplement to provide a final dietary Na concentration ranging from 7·0 to 18·0 g per kg DM.Dry matter (DM) and organic matter (OM) intakes were significantly reduced for groups receiving salt supplementation. The digestibilities of DM and OM were reduced for all groups on the low sodium grass diets compared with the high sodium grass diet, but were not affected by salt supplementation.No consistent changes were observed in the molar proportions of volatile fatty acids in rumen fluid, but N availability and retention were higher for the animals on the high sodium grass diet.The high sodium grass diet gave a better apparent availability and retention of minerals than the low sodium grass diets and, while addition of salt tended to improve the availability of minerals, the urinary loss of minerals increased with salt addition to the diet.There were no changes in plasma Na levels, and plasma K changes were inconsistent. However, plasma Ca concentration was reduced significantly for salt-supplemented diets with a Na concentration above 7·0 g per kg DM, and plasma Mg was significantly depressed at dietary Na concentrations above 15·0 g per kg DM.

Notes: An investigation of the carbon economy of single S184 white clover plants nodulated with an effective strain of Rhizobium trifolii growing on N-free nutrient solution and supplied with 150 parts/106 N as NH4NO3 has shown that 10% more of the C fixed per day is available for growth in the plants supplied with combined N. The difference between the two groups of plants is a result of higher respiratory activity in the roots of plants growing exclusively on N2. In terms of shoot growth, however, the difference in growth rate is likely to be less than 10%, because the rate of root growth is greater in the plants supplied with a moderate level of combined N. There is no evidence that NO-3 and CO2 compete for photosynthetically produced reductant in the leaves of plants grown on N2+NH4NO3, since no reduction in net photosynthesis was observed in plants assimilating combined N.An experiment carried out on detached leaflets of white clover grown on N2 and on N2+ NH4NO3 has shown that NO-3 -reducing activity is present in the leaflets of plants grown on N2+ NH4NO3 but not in plants grown on N2 and that the activity is light-dependent. Measurements of 14CO2 respired in the light and dark by leaflets previously allowed to photosynthesize 14CO2 showed that the ratio of 14CO2 output in the light to 14CO2 output in the dark was no higher in plants grown on N2+ NH4NO3 than in plants grown on N2. This observation is consistent with the finding that N source does not affect net photosynthesis in whole plants.

Notes: Two experiments were conducted to estimate the influence of initial cutting dates in March and April and of cutting frequencies on Guinea grass, elephant grass and star grass productivity. Increasing delay in date of first cut in the season resulted in a progressive increase in dry-matter yield. 72–81% of the tiller population at any cut were vegetative and this helped to maintain good aftermath yield for each date of first cut. Early April cuts gave the highest dry-matter yield and early March the least.Harvesting frequencies affected the sward productivity such that the annual dry matter yield increased with increasing harvesting interval from 6800 kg ha-1 for a 3-week interval to 13,000 kg ha-1 for a 10-week interval. The proportion of green leaf in the dry matter dropped from 57·7% at 3-week intervals to 32·0% at 10-week intervals. Seasonal effects showed that potential yield was reduced by a short interval between harvests early in the season but not late in the season. Species differences in quality and in the harvesting interval that gave the maximum yields were noted. These results are discussed in relation to management of the sward throughout the growing season.

Notes: A preliminary investigation evaluated six grass-suppressing herbicides applied on two occasions in late winter to a predominantly ryegrass ley containing only 15% ground cover of white clover. Substantial increases in clover growth, estimated visually, and flower head numbers per unit area were recorded in the first summer after treatment with 2·8 kg ha-1 carbetamide, 0·8 kg ha-1 propyzamide and 0·6 kg ha-1 paraquat. To achieve these increases, visual estimates suggested that spring growth of grass was reduced by 40–80%. However, grass growth recovered fully by mid-summer on the majority of the treatments.The following year five of the herbicides were compared in a field experiment. Dry matter (DM) and nitrogen (N) assessments of the grass and legume components were made at three harvests in the first growing season and a single harvest in the second year. Carbetamide, paraquat and, especially, propyzamide increased the proportion of clover in the DM (to 89% in the case of 1·2 kg ha-1 propyzamide); in general, using herbicides to raise clover contents above 20% lead to reductions in spring grass growth of about 70%. However, such reduction was offset by subsequent increased growth so that total annual yields were largely unaffected. The increased legume content resulted in an increased N concentration in both grass and legume components, measured in the second summer. At this time, the greatest increase in total N yield (up to 35%) was recorded from 0·6 kg ha-1 propyzamide. Potential uses to achieve legume dominance by grass-suppression are suggested and the needs for further research are outlined.

Notes: The effect of sowing date, within the period from late May to mid-August, on the DM yield of five leafy forage brassica crops sown to a stand was examined over the period 1976–78. Kale was the crop most sensitive to variation in sowing date and yields declined progressively with later sowings. There was no yield benefit from sowing rapes or stubble turnips earlier than mid- to late-June. Raphanobrassica produced yields as good as rape when sown in June. In 1978, DM yields of rape, kale and Raphanobrassica increased from September to early November, largely as a result of stem growth; kale was slower to accumulate DM than rape in late summer but continued growing longer into the autumn. The DM concentrations of all crops increased from September to December. Rape had a higher DM concentration than stubble turnip. Raphanobrassica was 10–25 g kg-1 lower in DM concentration than rape or kale. Raphanobrassica produced 23–59% flowering plants from late-May to early-June sowing. Harvest date affected DM yield and concentration, leaf: stem ratio and flowering percentage. The effects of sowing dale on DM concentration were small.

Notes: Herbage dry-matter yields of sown plots of white clover were greatly reduced by a natural infection of clover rot (Sclerotinia trifoliorum), the extent of the reduction being related to the level of infection. Examination of seasonal yield patterns suggested that although the plants apparently recovered from the disease it re-exerted its influence later in the season. No effects on seed yield could be detected but effects on the development of inflorescences and the proportion of ripe heads surviving to harvest were noted. Marked differences between varietal types existed for some of the characters examined.

Notes: A simple technique for extracting stem nematodes from air-dried samples of lucerne is described. The technique was found to be suitable for use in a breeding programme to improve resistance to stem nematodes in lucerne.

Notes: Book review in this article Ecology and Utilization of Desert Shrub Rangelands in Iraq By D. C. P. Thalen Population Biology of Plants By J. L. Harper How Grasses Grow By R. H. M. Langer Plant Strategies and Vegetation Processes By J. P. Grime Proceedings of the 36th Southern Pasture and Forage Crop Improvement Conference, 1979. Beltsville, Maryland, USA. Tropical Pasture Seed Production By L. R. Humphreys

Notes: The history and development of the multiple-probe capacitance meter used for in situ, non-destructive estimations of herbage mass is reviewed. An elementary, semi-theoretical electric-field analysis focuses attention on the inherent difficulties associated with the multiple-probe approach. This report establishes the background for the introduction of an ‘earth-plate’ capacitancemeter.

Notes: Studies have been carried out to measure the response to selection for canopy characters, as measured on young spaced plants, and the associated changes in sward yield in Lolium. In addition certain of the selection lines were compared with and found to be more productive than several existing bred varieties, indicating the considerable scope for improvement of dry matter yield through breeding.The canopy characters which were associated with high yield are compared with those which confer high yielding ability on a spaced plant and an individual in a community. The plant breeding implications of the results are briefly discussed.

Notes: A series of preliminary trials is described to assess the potential and some of the cultural requirements of new cultivars of forage peas grown as pure stands in the west of Scotland. Optimum sowing date was late March for harvesting 15 weeks later to leave sufficient of the growing season for a catch crop or the establishment of a grass sward. Yield of dry matter (DM) at harvest was approximately 6 t ha-1 but DM concentration varied greatly with season. The digestibility of the organic matter was of the order of 0·700 and the crude protein concentration in the DM 170 g kg-1. DM yield increased with increasing seed rate up to 200 kg ha-1 the maximum rate tested.

Notes: Thousand-seed weight, germination and seedling dry weight were measured in some tetraploid hybrid ryegrasses to study variations in seed quality. In cv. Sabrina, seed from spaced plants had a higher 1000-seed weight and seedling dry weight, and a slower germination rate than seed from narrow drills. Seed from later emerging groups of inflorescences had a low 1000-seed weight and seedling dry weight, but a high germination rate. Seeds of cv. Sabrina, Leri and Augusta harvested at between 10 and 25 d after peak anthesis had low 1000-seed weights, low germination rates and low seedling dry weights. Air temperatures between inflorescence emergence and seed maturity also affected seed quality; an increase in temperature from a 15°/10°C regime to a constant 25°C environment reduced 1000-seed weight and seedling dry weight, but increased germination rate. It is concluded that year-to-year variation in seed characters will occur because of temperature and other climatic changes, but seed quality can also be influenced by the time at which the seed is harvested. If combine harvesting is carried out at a moisture concentration of about 400 g kg-1 (≡40%) then maximum yields of seed of a high quality should be obtained.