THE USE OF RUMEN-FISTULATED STEERS IN THE DIRECT DETERMINATION OF NUTRITIVE VALUE OF INGESTED HERBAGE IN GRAZING EXPERIMENTS

A rumen-fistulated steer was used for the manual collection of samples of freshly swallowed herbage, in a grazing-management experiment on a perennial ryegrass sward. Diurnal and seasonal changes in the in vitro digestibility of the herbage selected by the grazing animal were studied under both strip- and continuous-grazing methods of management.
There was no appreciable change in digestibility as the sward was grazed down from upper to lower layers under strip-grazing management in April and May. In June to October a within-day fall in digestibility was found, much of which was attributable to an increase in the amount of old dead herbage grazed from the lower regions of the sward. Dead herbage taken in by the grazing steer was considerably lower in digestibility in August than in May. The in vitro digestibility of herbage samples, cut to ground level before and after grazing in a strip-grazed treatment, fell markedly as the proportion of dead herbage in the sample increased, giving a high negative correlation.
In a continuous-grazing management there was no pattern of diurnal variation, and the seasonal variation in digestibility of the ingested herbage was less than in strip grazing. The implications of these results are discussed in relation to indirect methods of digestibility determination (faecal-index technique), the measurement of herbage intake, and to some aspects of grazing management.     

LOSSES IN THE NUTRITIVE VALUE OF HEAVILY-WILTED HERBAGE ENSILED IN EVACUATED AND NON-EVACUATED POLYTHENE CONTAINERS

A conservation experiment is described in which the losses entailed in ensiling heavily-wilted herbage of 37–43% dry-matter content either by complete sealing in polythene alone, or by complete sealing followed by evacuation of air, were investigated.
The metabolizable energy values of the grass and silages were determined, and the silage volatile-acids fraction investigated by gas chromatography. The results indicate that there are no significant fermentation differences between the two types of silage. The mean dry-matter loss for the sealed, unevacuated silos was 6.5% and for the evacuated silos 7.8%. These losses, and the individual crude- and digestible-nutrient losses, are discussed in relation to other published work.     

THE NUTRITIVE VALUE OF WEEPING LOVEGRASS DURING THE SPRING SEASON

A continuous digestibility trial, lasting 50 days with subperiods of 5 days each, was made with the spring regrowth of Eragrostis curvula grown in the semi-arid region of Argentina. Five sheep were used to measure the digestibility of DM, organic-matter, cell-wall contents and N. DM yield was estimated simultaneously. The fall in digestibility of all fractions examined was described by quadratic equations. Cell-wall digestibility explained 91% of the variation in organic-matter digestibility. The rate of decrease in crude-protein digestibility increased with time and was particularly noticeable after about 40 days of growth. Digestible DM yield increased at a decreasing rate as maturity advanced, but digestible crude-protein content decreased linearly throughout the trial. It is concluded that the optimum stage of maturity for weeping lovegrass utilization depends upon the performance required from the animals that are to utilize it.     

THE NUTRITIVE VALUE OF WEEPING LOVEGRASS DURING THE SPRING SEASON

Faecal samples from a continuous digestibility trial with Eragrostis curvula were analyzed for cell-wall contents, acid-detergent fibre, lignin, asb and N. DM digestibility was regressed on all these fractions and organic-matter digestibility was also regressed on faecal organic-matter N. The best predictions of digestibility were obtained by the use of faecal lignin as a percentage of acid-detergent fibre, and by cell-wall contents. N was a comparatively poor predictor and it is shown that its relationship with organic-matter digestibility varies with the level of N in the diet. It is concluded that both lignin and cell-wall contents could serve as useful internal indicators since their use is unlikely to be biassed by metabolic and microbial contamination.     

A NOTE ON THE USE OF THE POWER-DRIVEN SHEEP-SHEARING HEAD FOR MEASURING HERBAGE YIELDS

3-inch sheep shears powered by various motors have been used extensively for sampling in grazing experiments at Hurley since 1958. General observations on their use are made and the results obtained in comparisons of sampling methods made in 1958 and 1959 are discussed.     

THE NUTRITIVE VALUE AND AGRONOMIC ASPECTS OF SOME FODDERS IN NORTHERN NIGERIA

The results of digestibility trials are presented on Andropogon gayanus, Brachiaria brizantha, Chloris gayana (Rhodes grass), Cynodon dactylon (Bermuda grass), Hyparrhenia rufa (Janagua grass), Panicum maximum (Guinea grass), Pennisetum pedicellatum, P. purpureum (Elephant grass), unimproved bush grass, Centrasema pubescens (Centro), Desmodium scorpuris and Stylosanthes gracilis (Stylo). The nutritive values are discussed, together with agronomic aspects important in relation to the growth of these species in Northern Nigeria.     

THE NUTRITIVE VALUE AND AGRONOMIC ASPECTS OF SOME FODDERS IN NORTHERN NIGERIA

Digestibility data are presented on the following; Andropogon gayanus hay and bush foggage, Arachis hypogoea (groundnut) haulms, Glycine max (soya-bean) hay. Sorghum vulgare (sorghum) leaves and hay, Stizolobium sp. (velvet bean) hay, Vigna sinensis (cowpea) hay and haulms, and S. vnlgare/Stizolobium sp. mixture. The results are discussed from the agronomic aspect.     

THE NUTRITIVE VALUE AND AGRONOMIC ASPECTS OF SOME FODDERS IN NORTHERN NIGERIA

The results are presented of digestibility trials on silage samples made from the following materials: Andropogon gay anus, Chloris gayana (Rhodes grass), Hyparrhenia rufa (Jaragua grass), Panicum maximum (Guinea grass), Pennisetum pedicellatum, P. purpureum (Elephant grass). Sorghum vulgare (sorghum), Acanthospermum hispidum, Helianthus annuus (sunflower), Stizolobium sp. (velvet bean), Zea mays (maize) and mixtures of A. gayanus/P. pedicellatum, Arachis hypogoea (groundnut haulms)/ P, pedicellatum. Sorghum vtdgare/Stizolobium sp., Z. mays/Vigna sinensis (cowpea). The results obtained, also the agronomic aspects of the subject and the use of the materials as fodder for cattle during the dry season are discussed.     

A NOTE ON THE EVALUATION OF THE NUTRITIVE VALUE OF FORAGE CROPS BY THE ACETYL BROMIDE TECHNIQUE

It has been shown in the past that in vitro digestibility of forage crops could be accurately predicted by the acetyl bromide absorption technique. This note demonstrates that in vivo digestibility values can be accurately predicted by this method and that in this respect the method is comparable in accuracy with the in vitro digestibility technique.     

A PORTABLE-CORRAL TECHNIQUE FOR MEASURING THE EFFECT OF GRAZING INTENSITY ON YIELD, QUALITY AND INTAKE OF HERBAGE

A grazing experiment using four stocking rates of sheep, equivalent to 34, 45, 57 and 68 sheep/ha on an assumed 200-day grazing season, was conducted using a portable grazing corral technique. Plots were subjected to fotir grazing periods between mid May and early September. The effect of stocking rate on herbage yield and quality and the influence of these factors and feed intake on liveweights of the sheep were recorded. The mean daily herbage organic matter available over the trial was 9.6, 5.8, 3.3 and 23% of the total liveweight of the sheep at each of the four stocking rates. The highest grazing pressure led to the production of high-quality herbage, but also led to reduced productivity, low feed intake and liveweight losses. The most lenient grazing pressure failed to provide adequate herbage utilization. Even at the most intensive stocking pressure, only 66% of the herbage available to ground level was utilized in grazings after July. Intake results suggested that sheep of 45 kg liveweight required 1000–1200 g digestible organic matter per day to maintain body weight. Despite the higher in vitro digestibility of herbage on offer at the higher stocking rates, intake was limited through lack of herbage; a high degree of correlation existed between herbage availability and herbage intake over the four stocking rates and at all grazings. It is concluded that the portable corral technique is well suited for grazing studies and the assessment of sward response to varying stocking rates and is particularly useful where facilities for more extensive studies are limited.     

STUDIES IN THE DIGESTIBILITY OF HERBAGE

Data from 291 digestion trials have been used to derive regression equations relating the organic-matter digestibility of herbage to the nitrogen percentage of its dry matter and to the nitrogen percentage in the organic matter of the resulting faces.
The residual errors are very high and it is shown that the deviations from the lines are not randomly distributed but have a seasonal trend. The seasonal biases have been calculated, and the inclusion of month of cutting as a factor is found to improve the two regressions to some extent. Monthly regressions have also been calculated. Even with these, however, the errors are still too high for many practical purposes.     

STUDIES IN THE DIGESTIBILITY OF HERBAGE

This paper presents the results of 125 digestion trials with sheep fed herbage at different stages of growth from three clover-free pure grass swards. During 1958 and 1959, a study was made of the yield, leaf lamina, nitrogen, ash and digestible organic matter percentage ( D ) of first growths, of regrowths cut at monthly and two monthly intervals and of swards receiving various quantities of fertilizer nitrogen.
For first growths in the spring D remained almost constant until the ears started to protrude from the leaf sheaths and then fell rapidly at approximately 0·5 per cent per day. The D values for S 23 ryegrass were three weeks later than S 24 ryegrass, which correspond with later ear emergence of the latter. S 37 cocksfoot was always less digestible than S 24 ryegrass although both were at similar stages of growth. This difference in D also occurred in the regrowths. The D of monthly regrowths tended to fall with each successive cut, although in 1959 ryegrass values improved in the autumn.
Fertilizer nitrogen had little effect on D .
Despite the warmer spring and drier summer in 1959 and corresponding changes in production per acre there was little effect on D .