Abstract:

[Objective] This study aimed to investigate the effects of dietary yeast culture supplementation on production performance, slaughter performance and visceral organ indices of fattening Kazakh sheep. [Method] A total of 30 three-month-old Kazakh rams were randomly divided into 0 YC group （control group）, 20 YC group and 40 YC group with 10 in each group. Under the same feeding and management conditions, the 0 YC group fed a basal diet with a concentrate to roughage （concentrate∶corn silage） ratio of 70∶30, and the 20 YC and 40 YC groups fed the same basal diet supplemented with 20 and 40 g yeast culture per ram per day, respectively. The feeding experiment lasted for 31 days. On 1^st and 30^th days of the experiment, the rams were weighed before morning feeding. The daily amount of feed offered to the rams and the remaining amount of feed in each sheep barn were recorded. The average daily gain, average daily feed intake and feed to gain ratio during the experiment were calculated. On the final day of the experiment, 5 Kazakh rams with comparable body weights were chosen at random from each group and slaughtered. The indicators associated with slaughter performance were measured, and the visceral organ indices were calculated. [Result] There were no significant （P>0.05） differences in the average daily gain, average daily feed intake and feed to gain ratio among different groups. Compared to the 0 YC group, the average daily gain in the 20 YC and 40 YC groups increased by 7.75% and 5.67%, respectively; the average daily feed intake in the 20 YC group increased by 4.23%; the feed to gain ratio in the 20 YC and 40 YC groups decreased by 3.40% and 5.80%, respectively. In addition, the average daily feed intake and average daily gain in the 20 YC group were slightly higher than those in the 40 YC group （P>0.05）. Compared with the 0 YC group, the live weight before slaughter, carcass weight and slaughter rate in the 20 YC group increased by 1.30%, 7.32% and 5.95%（P>0.05）, respectively, while those in the 40 YC group increased by 1.66%, 7.22% and 5.24%（P>0.05）, respectively. The tail fat weight in the 20 YC and 40 YC groups decreased by 13.67% and 9.38% （P>0.05） compared with the 0 YC group, respectively. The live weight before slaughter and tail fat weight in the 20 YC group were slightly lower than those in the 40 YC group （P>0.05）, while the carcass weight and slaughter rate were slightly higher than those in the 40 YC group （P>0.05）. The indices of heart, liver, lung, spleen and kidney in the 20 YC and 40 YC groups were slightly higher than those in the 0 YC group, but the differences were not significant （P>0.05）. The improving effect on visceral organ indices in the 20 YC group was slightly superior to that in the 40 YC group. [Conclusion] Dietary yeast culture supplementation has positive effects on production performance, slaughter performance and visceral organ indices of fattening Kazakh sheep, and the effects are better when the supplementation amount is 20 g per day per ram.

Key words: Kazakh sheep, yeast culture, production performance, slaughter performance, visceral organ index