Abstract:
Proc. Amt. Sot. ArGn. Prod. 1994 Vol. 20 EVALUATION OF GRAIN LEGUMES IN FEEDLOT RATIONS FOR SHEEP G.R. CASBURN, M.K. RICE and N. SRISKANDARAJAH School of Agriculture and Rural Development, University of Western Sydney-Hawkesbury, Richmond, N.S.W. 2753 Broad leaf lupins (Lupinus albus) are bein, b 0 Or-own increasingly to provide grain for livestock but there is limited information on their value for ruminant feeding. Two experiments were conducted to evaluate L. albus in comparison with narrow leaf lupins (L. angustifolius) and field peas (Pisum sativum) as main components of feedlot rations. In experiment 1, 9 first cross lambs, average liveweight 39 k,, housed in metabolism cages, were fed 0 700 g/day of 1 of 3 rations in a digestibility trial designed as a 3 x 3 latin square. The rations contained 70% of 1 of the 3 grain legumes and 30% of lucerne chaff on an as fed basis. Digestibility measurements were made in the last 7 days of each 17 day period. A fourth group of 3 lambs received a ration of 100% lucerne chaff for 1 period only. In experiment 2, 60 first cross lambs were housed in floor pens, 10 lambs/pen. Two pens were allocated randomly to each of the 3 grain legume rations. Lambs were fed ad Zibitum with access to fresh feed and fresh water daily. Feed intake and liveweights were recorded for 28 days, after an initial 10 day acclimatisation period. In experiment 1, organic matter digestibilities of the 3 rations were not significantly different (Table 1). The calculated digestible organic matter in dry matter values for the grain legumes were 88% for L. albus (ALB), 89% for L. arzgustifolius (ANG) and 90% for field peas. Fibre digestibility of ALB ration was significantly lower than that of the other 2 rations (P c 0.05). In experiment 2, average daily feed intake was 1.46 kg/animal. Liveweight gain and N balance were significantly higher in lambs fed the ANG ration compared to the others (P c 0.05). Feed conversion over the whole trial period was better in lambs fed the 2 lupins than those fed the field peas. Lambs fed ANG received the feed for a week preceding the trial and may have benefited from the acclimatisation to the diet. It can be concluded that broad leaf lupins are comparable to narrow leaf lupins as a feed source for lambs, provided the difference in protein content is taken into account. Table 1. Chemical composition (g/kg DM) of Lupinus albus (ALB), L. angustifolius (ANG), field peas (FP) and lucerne chaff (LC) used in experiments 1 and 2, digestibility (%) of organic matter (OM), nitrogen and neutral detergent fibre (NDF) in rations fed in experiment 1 and nitrogen balance (g/day), liveweight gain (g/day) and feed conversion ratio (FCR) in lambs fed rations containing grain legumes in experiment 2 395