Productivity of early-weaned lambs fed high-grain diets of wheat, oats or barley with or without lupin grain

Abstract

Poll Dorset x (Border Leicester x Merino) lambs were weaned at 6 weeks and fed ad libitum diets of whole wheat, oat or barley grain with 0, 15, 30, 45,60 or 75% lupin grain, or all lupin grain, for 11 weeks. All diets included 10% hay. The lambs adapted to diets containing barley and wheat more quickly than to diets containing oats. Digestibilities of grain DM with hay alone were: wheat 83%, oats 73%, barley 75%, and lupins 83%. Inclusion of lupins in wheat-based diets had no effect on digestibility or intake of feed or weight gain of lambs. Inclusion of lupins with oats increased digestibility ( P < 0.05) and intake of feed (P< 0.05) and caused a slight rise in feed intake:liveweight gain ratio, but greatly reduced feed intake:carcass gain ratio (P< 0.05). Inclusion of lupins with barley increased digestibility and intake of feed (P< 0.05), and caused a slight fall in the feed intake:liveweight gain ratio (P<0.05) and a large fall in the feed intake:carcass gain ratio (P<0.05). Responses to lupins were generally most pronounced as lupin content increased from 0 to 30%. Liveweight, carcass weight, wool growth, abdominal fat and muscle depth at rib 12 were all linearly related to intake of digestible DM (P<0.05). Dressing percentage increased up to a maximum as daily intake of digestible DM increased to 0.55 kg/sheep and then fell (P<0.05). Liveweight was greater, but dressing percentage less, for lambs fed oats than for those fed barley or wheat (P<0.05). Carcass weights of lambs fed different grains were therefore similar at the same intakes of digestible DM.