摘要:

AbstractThe 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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01584.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThree field experiments showed that perennial ryegrass can be successfully slot‐seeded into an existingFestuca‐Agrostissward. 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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01585.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractItalian 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 followi

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01586.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractAn 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 popula

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01587.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractIn three separate feeding experiments using a total of thirty individually‐housed Ayrshire cows three silages made from perennial ryegrass were givenad libitumtogether with supplements of four different hays in the long form. Thein vitroD‐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 amoun

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01588.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractTwo 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 thein vivodigestibilities 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 atad libitumaccess 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‐1post 50% ear emergence. The results of experiment 2 indicated a decrease of 0·207 units d‐1in 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 allowedad libitumaccess to feed. This may be a response t

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01589.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractEight samples of perennial ryegrass‐white clover herbage within vivodry 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 within vivoDMD 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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01590.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractAn 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 tim

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01591.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe 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‐1to 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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01592.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractTwo 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 fedad libitumon 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 fiel

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01593.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY