ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01475.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe 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‐1N) 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‐1N applied at sowing. Grass growth alone was increased at 120 kg ha‐1N 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‐1N 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‐1N 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‐1N and lowest at 120 kg ha‐1N.It is suggested that circumstances exist when the use of a relatively low starter N dressing (20–60 kg ha‐1N) 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‐1N), preferably delayed until the seedlings are in a position to take up the nitrogen

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01476.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractTwo experiments are described in which two levels of winter feeding and three levels of herbage allowance during the grazing season were imposed upon March/April calving British Friesian dairy cows. The winter treatments resulted in differences in live weight and milk yield at turnout of 35 and 53 kg and 3·4 and 3·2 kg d‐1for the two trials. Subsequently, when grazed at generous herbage allowances, the cows were able to compensate for much of this difference but when herbage was restricted the milk yield differences were accentuated.Groups of cows from each winter treatment were offered 25, 50 or 75 (Experiment 1) and 30, 50 or 70 (Experiment 2) g herbage DM per kg LW daily during the grazing season. Daily herbage intakes on the three allowances in each trial were 14·1, 13·3, 10·7 and 12·5, 12·1, 11·5 kg OM and milk yields were 16·0, 15·3, 12·5 and 15·2, 14·3, 11·8 kg SCM respectively. Both intake and milk production were depressed once the cows were forced to consume more than 50% of herbage on offer or to graze the sward down to a mean height of less than 8–10 cm. Grazing behaviour observations indicated that under rotational managements the cows did not compensate for restrictions in available herbage by grazing longer. Highest levels of milk production per unit area were observed in both trials when production per cow was de

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01477.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractMeasurements of herbage intake and ingestive behaviour were made on British Friesian calves 4–9 months old, which were strip‐grazed on swards of S24 perennial ryegrass at three (Experiment A) or four (Experiment B) levels of daily herbage allowance in three (A) or four (B) 12‐d periods. Herbage intake declined by approx. 18% as daily herbage allowance was reduced from 90 to 30 g DM per kg LW in both experiments, but the relationship between intake and allowance was not consistent between periods.Bite size and rate of biting were greater in calves on low than on high allowances after entry to a new strip of herbage but the positions were reversed towards the end of grazing. Reduced herbage intakes at low allowance resulted from reductions of approx. equal magnitude in bite size, rate of biting and grazing time, though not all of these effects were significant. It is suggested that these responses result from the increasing difficulty of prehending and ingesting herbage as swards are grazed down. The calves at low herbage allowances did not increase grazing time, probably because their behaviour was conditioned by anticipation of a new allowance of herbage.Bite size and daily herbage intake were greater on a spring sward than on an autumn sward, but within experiments herbage intake was not consistently related to any of the sward characteristics mea

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01478.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractGroups 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 im

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01479.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA 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 thebm3mutant 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 thebm3gene into forage maize breeding programm

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01480.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThree grass silages of different chop lengths made from a uniform sward of S23 perennial ryegrass were compared in four experiments including a feeding experiment with twelve lactating cows, an eating behaviour study, a rate of passage investigation and a selection trial. The silages had median chop lengths of 9·4, 17·4 and 72·0 mm, termed short, medium and long, with pH values of 3·93, 3·94 and 4·17 and D‐values of 65·9, 65·2 and 64·4 respectively.The daily intakes of silage DM and the daily milk yields increased as silage chop length decreased. The milk yield response to shorter chopping was significant with a supplement of groundnut but not significant with a supplement of sugar‐beet pulp. Chop length had small and generally non‐significant effects on milk composition.Eating and ruminating times expressed as min per kg DM decreased as silage chop length decreased but the retention time of the silage residues in the entire digestive tract was not significantly affected by chop length. When offered simultaneously, the intakes of the individual silages were 52·2, 31·9 and 15·9% of the total DM intake for the short, medium and long treatments respectively.Although silage with a chop length of 9 mm had nutritional advantages over longer silages, it is concluded that the mechanical and economic aspects of silage making must be considered fully when defining op

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01481.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractFriesian heifers grazingCenchrus ciliariscv. Biloela were supplemented with 0, 3 or 6 kg concentrates daily during weeks 10–34 (±1·7) of lactation during either the rainy or the dry season. The overall responses to concentrate were identical between seasons at 0·27 kg extra milk and solids corrected milk per kg. Supplementation increased total feed intake and modified the grazing behaviour of cows. For each kg concentrate organic matter eaten, herbage organic matter intake was reduced by 0·64 and 0·42 kg in the rainy and dry seasons respectively and the time spent grazing by 11 min. Higher intakes in the dry season were the result of an increased rate of biting and were reflected in liveweight change but not milk

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01482.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractTwo experiments were carried out to examine the nitrogenous changes occurring in herbage during harvesting and ensiling. In the first, ryegrass‐clover was wilted rapidly in the laboratory (6 h) and in the field under good (48 h) and poor (48 h and 144 h) weather conditions. Protein breakdown and ammonia formation were negligible in herbage wilted rapidly and it was only when the crop was exposed to a prolonged wilt in humid conditions that appreciable proteolysis occurred. In the second experiment ryegrass‐clover was ensiled in laboratory silos after treatment with varying levels of formic and sulphuric acids. An additional treatment included herbage inoculated with a mixture of lactic acid bacteria and glucose. The silos were opened after 4 and 50 d and samples were analysed for protein‐N, ammonia‐N, water‐soluble carbohydrates and organic acids. There was a high negative correlation between level of addition of either acid and the degree of proteolysis and deamination. Even at the highest levels of formic acid (7·7 g per kg) and sulphuric acid (4·0 g per kg) additions, however, about 45% of the original herbage protein was degraded after 50 d in the silo. The inoculum treatment was also effective in reducing proteolysis, the effect after 50 d being comparable with formic acid applied at a rate of 4

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01483.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe vegetation of an upland deep peat soil consisting mainly ofFestuca rubra, Holcus mollis, Molinia caerulea, Juncus acutiflorusandPotentilla erectawas sprayed with 1·5 kg a.i. per ha glyphosate applied to separate plots at monthly intervals from April to August. In July of the following year, April and May applications showed no effect on sward composition while June, July and August treatments resulted in increasing proportions of mosses and bare ground. August spraying gave almost complete control of the indigenous species with the exception ofF. rubraand mosses. The results are discussed in relation to the establishment of improved pastures in upland areas by surface seeding

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01484.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY