20～35kg川中黑山羊蛋白质需要量研究OA北大核心CSTPCD

This study was conducted to determine the protein requirements of Chuanzhong black goat wethers with body weight ranging from 20-35 kg. One aim was to provide data for the improvement of goat feeding standards in China. A total of twenty-two 2.5-month-old Chuanzhong black goat wethers (BW=19.97±5.47 kg) were selected. Four kids were used in an initial comparative slaughtering trial,the eighteen remaining kids were used in a feeding and digestion-metabolism trial. The pre-feeding period was 14 days,and the formal trial was 82 days. Animals were divided into 3 treatments:an ad libitum feeding group (AL Group),a 75％ ad libitum feeding group (AL75 Group) and a 60％ ad libitum feeding group (AL60 Group). There were thus 6 kids (replicates) per treatment,and 1 kid per replicate. A digestion-metabolism study was performed 4 days before the end of the feeding test to collect all feces and urine. When the average weight of the test kids in the AL Group reached 35 kg,the feeding test was ended,and 4 kids (a total of 12) close to the average weight of the group,were selected for slaughter in each group. The carcasses were cryopreserved to be tested. It was found that:1) the final body weight in the AL Group was significantly higher than that of the AL60 Group (P<0.01). The net weight gains,average daily gains and dry matter intakes in the AL75 Group and the AL60 Group were significantly lower than those in the AL Group (P<0.01). The ratio of feed to weight of the AL60 Group was significantly higher than that of AL Group and the AL75 Group (P<0.05). 2) The live weights,fasting weights,carcass weights and net meat weights of goats in the AL Group were significantly higher (P<0.01) than those in the AL75 Group and AL60 Group. There were no significant differences in slaughter rates,net meat rates,carcass net meat rates and meat-to-bone ratios (P>0.05). The bone weights of the AL Group were significantly higher than those in the AL75 Group and the AL60 Group (P<0.05). 3) The differences in heart,spleen,and lung organ index of goats in the three treatment groups were not significant (P>0.05);the AL Group liver organ index was significantly higher than that of the AL75 Group and the AL60 Group (P<0.01),and the kidney organ index decreased significantly (P<0.01) with decrease in feeding level. 4) The maintenance net protein requirement of the 20-35 kg Sichuan black goats was determined as 1.60 g·kg-1·BW-0.75·d-1;while the net protein requirement for growth of goats with a daily gain of 100-300 g·d-1 (Npg) was 13.13-40.13 g·d-1,and the total protein requirement (Npr) was 28.26-63.15 g·d-1. These findings for Chuanzhong black goats provide a data reference for the improvement of local sheep and goat meat production and breeding standards in China.