ALBERT

Notes: Groups of calves and lambs grazed on plots of S23 perennial ryegrass, in successive periods of 2, 2 and 3 weeks, at stocking rates which resulted in a slow change in herbage mass on each plot and measurements were made of ingestive behaviour (biting rate, bite size and grazing time) and herbage intake.As the green herbage mass was progressively reduced from approx. 3000 to 1000 kg OM per ha between periods, biting rate and grazing time increased, but insufficiently to offset the rapid fall in bite size so that herbage intake declined by 24% and 39% for calves and lambs respectively. Patterns of response were similar in calves and lambs, though in all parameters except biting rate the lambs appeared to be more sensitive than the calves to changes in sward conditions and there was no evidence that lambs were better adapted to grazing on short swards than calves.Intake increased in both calves and lambs up to levels of 2500–3000 kg green OM per ha, though this response may have been attributable in part to the reinforcing effects of increasing herbage mass and diet digestibility. Lambs consistently selected a more digestible diet than calves.Both calves and lambs increased grazing time substantially in response to limiting sward conditions, in contrast to results in earlier strip-grazing trials with calves, thus supporting the suggestion that the lack of response under strip-grazing is a characteristic of the management imposed.

Notes: The effects on clover and grass growth of five levels of ammonium nitrogen (NH4-N) applied before sowing, at sowing and after nodule initiation have been investigated. A pot experiment in which S184 white clover was grown in a peat soil showed that NH4-N up to 688 mg N per pot (approx. equivalent to a field rate of 120 kg ha-1 N) applied before sowing and at sowing did not affect clover growth. N-fixing activity (C2H2-reduction), on the other hand, was reduced progressively up to the highest level (688 mg N per pot). Application after nodule initiation increased growth relative to the zero-N treatment at all levels of application. Maximum growth and N fixation occurred at 516 mg N per pot where the DM yield was 70% higher than in the absence of added N. A field trial in which S184 clover and S24 perennial ryegrass were surface sown on to a peat soil showed an increase in grass and clover growth in the first year in response to 120 kg ha-1 N applied at sowing. Grass growth alone was increased at 120 kg ha -1 N applied 40 d before sowing. Lower rates of application before sowing and at sowing did not affect clover or grass growth. The effect of the delayed application of NH4-N on legume growth was less marked than that in the pot experiment, 90 kg ha-1 N stimulating clover growth by 40% in the first year. The effect was however different from that in the pot experiment, in that, whilst 30kg ha-1 N increased N fixation relative to the zero-N treatment, plants exposed to higher levels showed a depression in N-fixing capacity. N-fixation was correlated with nodule numbers in the delayed NH4-N application, the closest correlation being with the number of multilobed nodules which was highest at 30 kg ha-1 N and lowest at 120 kg ha-1 N.It is suggested that circumstances exist when the use of a relatively low starter N dressing (20–60 kg ha-1 N) at sowing would not increase clover or grass growth in the early stages of the establishment of a hill reseed. Under such circumstances higher rates of application (100 kg ha -1 N), preferably delayed until the seedlings are in a position to take up the nitrogen rapidly, would have the greatest effect.

Notes: A field trial with maize (Zea mays) was sown in two successive years at Hurley to examine whether the advantages in terms of low lignin concentration and high digestibility demonstrated in USA and France for the‘brown mid-rib-3’(bm3) mutant over its otherwise isogenic counterpart would still be manifest in a cool maritime climate. Plants of the bm3 mutant and the normal counterpart (cv. Troyer Reid) together with a locally adapted earlier maturing variety (cv. Caldera 535) were grown in 1976 and 1977 and sampled on three occasions. Despite considerable contrast in the two growing seasons, 1976 being unusually hot, differences of 4 to 8 units in whole-crop D-value and 6 to 10 units in stover D-value were demonstrated in favour of the mutant form, together with significantly lower lignin concentrations (1976, normal 22 g per kg DM, mutant 14; 1977, normal 25 g per kg DM, mutant 16). The results give strong support to the case for introducing the bm3 gene into forage maize breeding programmes in Britain.

Notes: The drying of Italian ryegrass (RvP) tillers under controlled conditions at three stages of growth is described. The rate of water loss was dependent on tiller morphology as well as on water content. Leaf laminae dried faster than stems and also aided the loss of water from stems. Drying time was shortest for vegetative tillers despite their high water content, and longest for reproductive tillers shortly before ear emergence. The practical implications in relation to haymaking are discussed.

Notes: Scots timothy was harvested three times a year for 3 years under four harvesting patterns and at all combinations of three levels of application of nitrogen and four of potassium. Harvesting patterns, H1, H2, H3 and H4, comprised cutting primary growth on 27–29 May or 14, 28 or 42 d later followed by cutting a first regrowth 8 weeks afterwards and a second regrowth on 15–16 October. N treatments, N0, N1 and N2, involved annual totals of 0,108 and 216 kg ha-1 N in three equal doses. K treatments, K0, K1, K2 and K4, involved annual totals of 0, 54, 108 and 216 kg ha-1 K also in three equal doses.Mean herbage DM yields in successive years were 8·90, 9·54 and 9·61 t ha-1 containing92·4%, 93·1% and 94·5% timothy, respectively. Systems H3 and H4 had 24% higher yields than H1 and H2. The superiority of the late systems derived from higher yields of primary growth. Mean response to 108 kg ha-1 N at 36·7 kg DM per kg N was significantly higher than the response to an additional 108 kg ha-1 N. Response in primary growth to successive increments of 36 kg ha-1 N averaged 53·9 and 27·5 kg DM per kg N. The first regrowth gave linear responses up to 72 kg ha-1 N. The possibility is discussed of more effective use of N by increasing the proportion applied to regrowth. Response to K was low except in the third year when there was a marked response at N2. It was calculated that to maintain soil potash it is necessary to apply 23·9, 47·7 and 86·6 kg ha-1 fertilizer K for each harvest at N0, N1 and N2 respectively.

Notes: The crude protein concentration, amino acid composition and protein quality of sainfoin (Onobrychis viciifolia) forage was compared to that of lucerne (Medicago sativa). The amino acid analyses showed that sainfoin contained higher amounts of lysine, histidine, proline, cystine, glycine, alanine, valine, leucine, tyrosine, phenylalanine and tryptophan than lucerne, whereas lucerne contained more aspartic acid, methionine and isoleucine than sainfoin; the limiting amino acid in both legumes was methionine. The protein score, an estimation of protein quality for nonruminants, was 68 for sainfoin forage and 71 for lucerne forage compared to 100 for an ‘ideal protein’. The similarity of protein quality of sainfoin forage to that of lucerne indicates that, where conditions permit, sainfoin could be grown for the production of protein as an alternative to other crops.

Notes: The outcome of spraying two bracken-infested hill sites in July with asulam at the commercial rate of 4·5 kg a.i. per ha was a 98% reduction in frond numbers which persisted for the following 3 years. Broad-leaved grasses, Agrostis tenuis, Agrostis canina and Poa pratensis, were susceptible to asulam and were severely reduced at both sites while fine-leaved grasses, Festuca ovina and Deschampsia flexuosa, were resistant. Over a period of 3 years after spray application the original bare ground under the bracken canopy and that produced by the effects of asulam was recolonized by the recovery of the broad-leaved grasses and an increase in the cover of herbs. The latter also increased on the unsprayed control areas.A favourable aspect and an abundance of the productive broad-leaved grasses appeared to be the main factors which determined the amount of increase in herbage yield observed following spray treatment. One such area gave a herbage DM yield of 3039 kg ha-1 during the growing season which was 47% greater than the control while an area with a less favourable aspect and dominated by the less productive fine-leaved grasses gave a herbage yield of 2069 kg ha-1 which was only 18% greater than the control.

Notes: The effects of cereal and protein supplements on feed intake and liveweight gain were studied. In 1975, steers were continuously stocked on autumn pasture and fed no supplement or 8 g dry matter (DM) per kg liveweight (LW) per d as rolled barley (crude protein (CP) concentration 120 g kg-1), lucerne cobs (CP concentration 190 g kg-1) or a mixed concentrate (CP concentration 300 g kg-1). In 1976, steers were continuously stocked or rotationally grazed in summer and fed no supplement or 7 g DM per kg LW per d as either rolled barley (CP concentration 130 g kg-1) or a mixture of rolled barley and groundnut meal (CP concentration 210 g kg-1). Herbage organic matter (OM) intakes in 1975 and 1976 were depressed on average by 22 and 15% respectively with supplementation, but total OM intakes were increased by 9 and 15% respectively. Daily liveweight gain was not significantly increased by supplementation in 1975 when herbage allowance was ample but was significantly increased in 1976 when herbage allowance was limited and herbage digestibility was lower. Protein concentration of the concentrate did not significantly affect daily gain in either year nor was there any difference in gain between rotational grazing and continuous stocking.

Notes: Two modifications have been made to the dry-weight-rank (DWR) method for measuring botanical composition. One previous limitation of the method has been that it gives biased results in pastures where there is a consistent relation between quadrat dry matter yield and the order in which species are ranked for yield. A weighting factor, applied to the DWR multipliers and based on pasture yield in quadrats estimated for dry weight rank, can correct for this bias. In routine pasture sampling quadrat yields are often visually estimated in the same quadrats in which composition is assessed by DWR. These estimated quadrat yields can then be used as weighting factors to improve the accuracy of DWR as well as to estimate pasture yield. Dry weight rank has also been unsuited to pastures which are heavily dominated by one species but this problem can be lessened by assigning more than one rank to the dominant species, a method referred to as ‘cumulative ranking’.Both these modifications were found to give a more accurate estimate of composition using data from a wide range of tropical and temperate pastures. On the other hand, creation of new DWR multipliers for particular cases was inadvisable. All data made available for this study and the original data ('t Mannetje and Haydock, 1963) were used to derive new multipliers: 0·705, 0·238 and 0·057. The overall benefits from using the new multipliers will, however, only be slight.

Notes: In 1976, 1977 and 1978 a red clover-perennial ryegrass sward was cut twice for silage, and in the autumn of 1976 and 1977 it was either grazed at low and high stocking rates, i.e. seventeen and thirty-four lambs per ha respectively, or was cut with a forage harvester. The effects of grazing on yield in the following year were examined.Herbage growth in the grazing period was slow and did not differ significantly between the treatments. The yield of silage dry matter taken in May and July was highest in ungrazed plots (9·8 and 8·1 t ha-1 in 1977 and 1978 respectively) and lowest in plots stocked at the high rate (5·9 and 5·7 t ha-1 in 1977 and 1978 respectively). The aftermath yield for grazing in 1977 was slightly but significantly greater on treatments grazed in the previous year compared with ungrazed treatments.Red clover content decreased markedly during grazing, the high stocking rate treatment containing 2·4% clover and the ungrazed treatment 57·3% clover. The high stocking rate treatment also had the lowest red clover content in the first silage cut. Red clover content in grazed plots increased to a level similar to that in ungrazed plots by the start of the grazing period in the subsequent harvest year.Animal performance was higher at the low than at the high stocking rate but herbage consumption per head did not differ significantly between the two grazing treatments.Possible reasons for the adverse effect of grazing on the red clover are defoliation and treading. It is concluded that such experiments can form the basis of an economic assessment of red clover and help the farmer decide whether or not he should integrate the crop into his system.