A study of the horizontal and vertical distribution of herbage in grass-dominant swards was made to assess the relative importance of different sources of wastage during grazing. A sward grazed by cattle under two contrasting managements was divided, for the purpose of herbage sampling, into two categories: ‘grazed’ herbage, on ground with no obvious dung contamination, and ‘dung patches’, which were of ungrazed or lightly grazed herbage resulting from the effects of faeces dropped at previous grazings. In each category, samples were cut at two successive heights to provide an estimate of the quantity of herbage in the upper region of the sward (over 2½ in. from ground level) and in the lower region (½-2½ in. from ground level).After grazing, some 35% of the original crop remained in ‘grazed’ areas, and some 20% in ‘dung patches’. In terms of vertical distribution, most of the residue (40% of the original crop) was in the lower region, from ½ to 2½ in. above ground level.Total production as live-weight gain was not significantly different, but the yield of conserved herbage was greater in treatment R (five rotations) than in treatment RR (nineteen rotations). Frequent grazing reduced herbage production, and this effect was not offset by any less intense defoliation of the frequently grazed sward. The average quantity of herbage residue was no higher in treatment RR than in treatment R, although the time of occupation per plot by the cattle in RR was only a quarter of that of the cattle in treatment R.

No abstract

1. In a population of Hereford crossbred steers carcass conformation was measured by weighing wholesale joints cut in London and Home Counties fashion and dissecting a single rib sample joint. Correlations were calculated between weight of joints and certain linear carcass measurements.2. Weights of individual joints in a group of good cuts were studied in relation to carcass composition estimated from sample joint dissection. Carcass fatness at constant carcass weight was correlated positively with some joints and negatively with others. A thigh width measurement was related to the weight of these joints in a similar fashion. This accounted for the low value of thigh width as an index of the proportion of good cuts.3. The weights of joints, and many of the measurements, were highly correlated with carcass weight. When carcass weight was allowed for, partial correlations were too low to support the use of linear measurements to predict weight of joints in individual carcasses.

Few experiments on the effect on animal production of varying levels of nitrogenous fertilizer applied to pasture have been reported. Such information is necessary to supplement data derived from small-plot trials. There are several factors in fertilizer usage which the presence of the grazing animal must affect. First, the re-circulation of nitrogen and other elements through dung and urine will add considerably to those applied as fertilizer. Watkin (1954) and Wolton (1955) have shown in this country how important these effects can be. Secondly, biting, treading, palatability and degree of utilization will affect total production of the fertilized swards as well as their rate of botanical change. A third factor is that in any closed grazing area with a fixed stocking rate, a rise or fall in rate of herbage growth has a strong cumulative effect, normally met by the conservation of excess herbage, since adjustment of stock numbers on the farm as a whole can only infrequently be made. Conservation therefore has an influence on total output. Last, but not the least important, is the influence on the grazing animal of herbage varying widely in its chemical composition as a result of the application of nitrogen fertilizer. The attainment of alevel of production per head equal to that from an untreated sward should allay doubts that fertilized herbage is nutritionally less satisfactory, at least in respect of fattening animals which are less sensitive to imbalance of elements than lactating and pregnant stock.With these points in mind, an animal production experiment was carried out at The Grassland Research Institute in 1955 and 1956 to study three rates of application to pasture of a nitrogenous fertilizer. Fattening steers were used to study rates of live-weight gain and carcass production. More fertilizer was applied in late than in early summer in order to obtain a more uniform growth of herbage and to extend the autumn grazing season. METHODSivard and layout. The experiment was conducted on a perennial rye-grass/white clover sward in its fourth and fifth harvest years on afree-draining loam soil overlying Upper Chalk. The seed mixture, sown in 1951, had formed a sward in which S.24 and S.23 rye-grass with white clover predominated; of the other legumes included at sowing only a few plants of lucerne remained.Four blocks, totalling 15 acres, were each permanently divided into four plots of 0-94 acre. Four treatments were allocated at random in each block.Treatments and stock.

No abstract