The purpose of this experiment was to study the characterization of growth performance,slaughter performance and organ development of Tibetan Gamba sheep under different relative feeding levels,so as to e-valuate the production value of Tibetan Gamba sheep.Thirty-six healthy male black Gamba sheep lambs with the same body condition and body size[average body weight(BW):(17.94±0.91)kg]were selected and randomly divided into 6 groups with 6 replicates per group and 1 sheep per replicate.According to the metabo-lizable energy and protein maintenance requirements of sheep in NRC(2007),the dietary metabolizable energy and protein levels of each group were designed with different multiples.Group Ⅰ:0.8 times of requirement for 20 kg BW and 100 g/d average daily gain(ADG);group Ⅱ:0.9 times of requirement for 20 kg BW and 100 g/d ADG;group Ⅲ:1.0 times of requirement for 20 kg BW and 100 g/d ADG;group Ⅳ:0.8 times of requirement for 20 kg BW and 200 g/d ADG,group Ⅴ:0.9 times of requirement for 20 kg BW and 200 g/d ADG;group Ⅵ:1.0 times of requirement for 20 kg BW and 200 g/d ADG.The pre-trial period lasted for 10 days and the experimental period lasted for 70 days.The results showed as follows:the final body weight,net gain,average daily gain of sheep in groups Ⅴ and Ⅵ had no significant differences(P＞0.05),while groupⅥ was significantly higher than the other 5 groups(P＜0.05);the ratio of feed to gain in group Ⅰ was signifi-cantly higher than that in the other 5 groups(P＜0.05);the feed cost increased significantly with the increase of relative feeding level(P＜0.05).Live weight before slaughter,carcass weight and net meat weight in groupⅥ were significantly higher than those in the other 5 groups(P＜0.05),while the live weight before slaughter in groups Ⅲ and Ⅴ had no significant difference(P＜0.05),but they was significantly higher than that in groups Ⅰ,Ⅱ and Ⅳ(P＜0.05);there was no significant difference in net meat weight among groups Ⅲ,Ⅳand V(P＞0.05),but they was significantly higher than groups Ⅰ and Ⅱ(P＜0.05);the abdominal fat weight of group Ⅵ was significantly higher than that of groups Ⅰ,Ⅱ and Ⅴ(P＜0.05).The liver weight and index of group Ⅵ were significantly higher than those of the other 5 groups(P＜0.05);there were no signifi-cant differences in heart,lung and kidney weights and indexes among the 6 test groups(P＞0.05);the weight and index of rumen of group Ⅵ were significantly higher than those of the other 5 groups(P＜0.05),and the weights and indexes of reticulum and omasum were significantly higher than those of groups Ⅱ and Ⅳ(P＜0.05).In conclusion,combined with feed cost and actual breeding economic benefits,it is recommend that di-et prepared according to 0.9 times the metabolizable energy and protein maintenance requirements of sheep with 20 kg BW-200 g/d ADG in NRC(2007),Tibetan Gamba sheep can obtain the better growth performance and slaughter performance.[Chinese Journal of Animal Nutrition,2024,36(8):5207-5216]
维普
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