Growth of lambs offered fixed amounts of roughage and concentrate either simultaneously or sequentially

Abstract

Two experiments were carried out in Scotland 1984 to study the efficiency of energy utilization by Suffolk x Blackface lambs. In the first experiment, a digestibility trial, the lambs were fed three diets: roughage (R) consisting of chopped dried grass; concentrate (C) containing 700 g whole barley, 225 g ground barley and 75 g fishmeal/kg dry matter (DM); and a mixed diet (M) containing 500 g of roughage and 500 g of concentrate/kg DM. The DM and organic matter digestibility coefficients of diet M were lower than the ' expected' values calculated by summation of the separately determined digestibility coefficients of the component feeds. Similarly, the metabolizable energy (ME) value was 40% lower than expected.In the second experiment, 40 lambs of c. 20 kg live weight (LW) were offered 50 kg roughage DM (ME 9-74 MJ/kg DM) and 50 kg concentrate DM (ME 12-21 MJ/kg DM) either as a mixture (treatment M) or sequentially (treatment S). Lambs on treatment S took 33 days longer to consume their allocation of food than those on treatment M, but achieved a similar final empty body weight and empty body composition. This contrasts with results predicted by a feeding standards model for lambs of a similar LW offered diets of the same ME content. The longer feeding period, and hence greater overall maintenance requirement, of lambs on treatment S was partly offset by associated effects causing a reduction in the total ME available to lambs on treatment M, and partly to improved efficiency of energy utilization for gain and/or a lower daily maintenance requirement of lambs on treatment S. Allowing for associated effects and the adoption of a variable maintenance requirement in current feeding standards would result in a more accurate prediction of animal performance. i N T P n m i r T i n N significantly longer. 0rskov et al. (1981) concluded iiNiKULiULiiuiN t h a t t h j s c o u l d b e a c c o u n t e d f o r b y a decrease in the A fixed quantity of roughage and concentrate may be maintenance requirement of the animals given split allocated to growing ruminants in several ways: e.g. feeds, or an increase in the efficiency of energy (i) a mixed diet containing equal proportions of utilization during re-alimentation following a period roughage and concentrate; (ii) split feeds, roughage of reduced nutrition. These results could also be alone being given until it is all eaten, followed by explained by differences in the carcass composition of concentrate; (iii) a progressive change from all the animals, as their protein and fat contents were not roughage to all concentrate; and (iv) half the animals measured. Williams et al. (1984) found no significant given roughage and half given concentrate. The results difference in carcass composition as determined by of these alternatives can be predicted from computer specific gravity measurements between their two models based on current feeding standards, but may groups, and concluded that associated effects caused be incorrect. a reduction in the energy available from straw when Re...

Growth of lambs offered fixed amounts of roughage and concentrate either simultaneously, progressively or separately

“…The percentage reductions in overall and roughage DM digestibility were 2-2 and 7-3% respectively. These values were lower than those obtained in our earlier experiment (Wilkinson & Greenhalgh 1991) of 39 and 8-5 % respectively, for similar diets, and those of Mould et al (19836), who obtained reductions of 2-9 and 10-9%, respectively, for a diet containing a 1:2 ratio of chopped hay and whole barley. In both of these cases, differences between the roughage and concentrate diets in DM and OM digestibility were greater than those obtained in the present experiment.…”

“…Lambs on diet M tended to select concentrate in preference to grass. A 50:50 intake was achieved using the method described by Wilkinson & Greenhalgh (1991). Faeces were collected daily by the bag and harness technique and stored at -20 °C prior to further analysis.…”

“…Voluntary food intake was estimated weekly. Lambs were slaughtered at the University farm by a skilled slaughterman as described by Wilkinson & Greenhalgh (1991) and carcass weights recorded. Lambs sent to the commercial slaughterhouse (Inverurie Scotch Meat) were slaughtered by the same procedure and all non-carcass components, except blood, were collected and weighed.…”

“…Slaughtered lambs were processed as three components: (i) half carcass (right side), (ii) non-carcass components (head and feet, pelt, gut and pluck organs) and (iii) blood, as described by Wilkinson & Greenhalgh (1991). Samples were analysed in duplicate for DM, CP, EE and ash.…”

Prediction of the body composition of lambs from the composition of their non-carcass components

“…Details of each experimental design and the chemical composition of experimental diets are presented elsewhere Greenhalgh, 1991 and. In experiment 1, 30 lambs ranging in live weight (LW) from 14-0 to 48-1 kg were slaughtered.…”