Effects of different nutrition levels in total mixed rations on production performance, apparent digestibility, and slaughter performance in yard feeding lambs.

The effects of three nutrition levels(A1,0.7×NRC,A2,0.8×NRC,A3,0.9×NRC) in total mixed rations on production performance,apparent digestibility and slaughter performance was evaluated.Forty-eight lambs were randomly divided into three groups for a two months feeding trial.The average daily weight gains of the A2 and A3 groups were significantly(P0.01) higher than that of the A1 group.There was no significant difference between A2 and A3.The average daily gain of ram lambs was significantly(P0.01) higher than that of ewe lambs.Different nutrition levels had significant effects on apparent digestibility of Ca,total phosphorus(TP),neutral detergent fibre(NDF) and acid detergent fiber(ADF)(P0.01).Sex factors had significant effects on apparent digestibility of Ca and TP(P0.01).There were no difference in slaughter indexes(P0.05) but the slaughter rate,cooking rate and loin eye area of hybrid lambs were significantly higher than those of Gansu alpine fine wool sheep.In summary,the 0.8×NRC nutritional level was better for fattening hybridized lambs of crossed SA Mutton Merinos,and ram lambs grew better than ewe lambs at the same nutritional levels.