ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01462.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe 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 caninaandPoa pratensis, were susceptible to asulam and were severely reduced at both sites while fine‐leaved grasses,Festuca ovinaandDeschampsia 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‐1during 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‐1which was only 18% greater

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01463.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe 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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01464.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractTwo 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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01465.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractIn 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‐1in 1977 and 1978 respectively) and lowest in plots stocked at the high rate (5·9 and 5·7 t ha‐1in 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 in

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01466.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractIn two 12‐week grazing experiments using twelve and eighteen spring‐calved cows in 1976 and 1977 respectively, the effects of feeding either a barley or a groundnut concentrate supplement were investigated. The mean yield of herbage DM on offer was 2330 and 2030 kg ha‐1, with crude protein concentrations of 192 and 193 g per kg DM in 1976 and 1977 respectively. Grazed herbage was the sole feed in the control treatment. In the other two treatments the herbage was supplemented with 3 kg per cow per d of a concentrate containing either 82·2% barley or groundnut with mean crude protein concentrations of 109 and 409 g per kg DM respectively. Similar results were obtained in both experiments with average daily milk yields of 18·3, 19·8 and 19·9 kg per cow on the control, barley and groundnut treatments respectively. The supplements had no significant effects on either milk composition or liveweight change. It is concluded, that with an ample supply of herbage of high crude protein concentration, a supplement of groundnut had no advantages over one

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01467.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe milk yields obtained from 845 herd‐years within the ICI Recorded Farms Scheme have been correlated, by multiple regression analysis, with the N fertilizer supplied to the grassland, the quantities of concentrates fed and the stocking rates. The large quantity of data gave highly significant correlations which indicated that, over the whole period, the supply of an extra 1 kg N from fertilizer was associated with an average extra yield of 9·9 1 milk. 4·9 1 were associated with the extra N independently of any simultaneous changes in either stocking rate or concentrate feeding, and 4‐5 1 were ascribable to a simultaneous increase in stocking rate. There was a substantial variation in the ‘milk yield per kg N’ response from year to year, but the average value over 6 years agreed closely with that observed in the perio

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01468.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractTwenty‐four British Friesian cows were allocated between six grazing treatments (two levels of herbage mass x three levels of daily herbage allowance) in a balanced change‐over design with four periods of 12 d each at monthly intervals. Herbage OM mass ranged from 3790 to 5770 kg ha‐1measured to ground level and daily herbage DM allowances were 30, 60 and 90 g per kg animal live weight. Herbage OM intake was lower at high than at low herbage mass (24·6 vs 26·3 g per kg LW), and was 26·9, 26·6 and 22·9 g per kg LW respectively at daily herbage DM allowances of 90, 60 and 30 g per kg LW. Milk yield was not affected by herbage mass but was depressed at the low herbage

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01469.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractSeed development and seed shedding were studied in seven populations ofLolium multiflorum.Five of these populations were from the North Italian Plains, two from the Piedmont area and three from the Lombardy region. The remaining populations were Delecta, a variety derived from ecotypes from the Lombardy Plain, and RvP Lemtal. Seed shedding was greatest in the three ecotypes from the Lombardy Plain and lowest in RvP Lemtal. The two ecotypes from the Piedmont Plain, and Delecta, gave intermediate values. Moisture loss during ripening was greatest in the Lombardy ecotypes but there were no differences in the time taken to reach maximum 1000‐seed weight. Germination values had reached a maximum 27 d after anthesis in all populations. It is suggested that the North Italian ecotypes, or varieties derived from them, should be harvested by direct combining at a moisture concentration of 450 g kg‐1(≡45%) to obtain the maximum weight of germinable

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01470.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe effects of water and nitrogen (N) availabilities and their possible interactions on the seed yield and yield components of S23 perennial ryegrass grown in pots in the glasshouse were investigated. Increasing the N fertilizer from 0 to 5 g per pot more than doubled the seed yield but no further increase in seed yield was found by increasing N fertilizer from 5 to 10 g per pot. The main effect of increasing water availability was to increase both seed and straw yield. When N had been applied, accumulated evapotranspiration was linearly related to seed and straw yield. The component of yield having the greatest effect on yield was the number of fertile tillers and, although both N and water availability affected this component, N had the larger effect. Implications of these responses are discussed in relation to the potential yield of the crop and to the field situation.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01471.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY