营养水平对舍饲天祝白牦牛冷季生产性能、营养物质表观消化率的影响

Effects of Different Nutrient Levels on Production Performance and Nutrient Apparent Digestibility of Tianzhu White Yak in Cold Season

试验旨在探究冷季补饲不同营养水平日粮对天祝白牦牛生产性能和营养物质表观消化率及经济效益的影响。选择体况良好的0.5岁、2.5岁和4.5岁天祝白牦牛公牛各10头,各年龄随机分为高营养水平组(H组)和低营养水平组(L组)进行饲喂,每组5头。H组和L组饲料综合净能(NE_(mf))分别为97.84、81.54 MJ/kg,预试期15 d,正试期90 d。结果表明:三个年龄段牦牛的日增重、胴体重和屠宰率均无显著差异(P>0.05),但H组三个年龄段料重比均低于L组牦牛。0.5岁H组干物质、酸性洗涤纤维表观消化率极显著或显著低于L组(P<0.01或P<0.05),2.5岁H组干物质和酸性洗涤纤维养分表观消化率显著低于L组(P<0.05),4.5岁H组粗蛋白表观消化率极显著高于L组(P<0.01),而中性洗涤纤维表观消化率极显著低于L组(P<0.01)。不同年龄H组和L组牦牛干物质、粗蛋白、中性洗涤纤维表观消化率随年龄增长极显著或显著升高(P<0.01或P<0.05)。三个年龄阶段牦牛分别饲喂等量日粮,L组利润均高于H组。说明冷季补饲精粗比为35∶65的低营养水平日粮可显著提高天祝白牦牛的生产性能和经济效益。

This experiment was designed to investigate the effects of cold season supplementation with dif⁃ferent nutrient level diets on the production performance and apparent digestibility of nutrients and eco⁃nomic benefits of Tianzhu white yaks.Ten Tianzhu white yak bulls of 0.5,2.5 and 4.5 years of age in good condition were selected and randomly divided into high nutritional level group(group H)and low nutritional level group(group L)for feeding,with 5 bulls in each group.The integrated net energy of feed(NE_(mf))of group H and group L were 97.84 MJ/kg and 81.54 MJ/kg,respectively,with a pre-feeding pe⁃riod of 15 d,and a positive test period of 90 d.The results showed that:daily weight gain,carcass weight,and slaughter rate of yaks at the three age betwee the two groups showed no significant differences(P>0.05),and the feed-to-weight ratio of the three age groups of group H was lower than that of group L yak.The apparent digestibility of dry matter and acid detergent fiber of group H at 0.5 years of age was extremely or significantly lower than that of group L(P<0.01 or P<0.05),and that the digestibility of dry matter and acid detergent fiber nutrients of group H at 2.5 years of age was significantly lower than that of group L(P<0.05),and the apparent digestibility of crude protein in group H at 4.5 years of age was highly significantly higher than that of group L,while the apparent digestibility of neutral detergent fiber was lower than that of group L(P<0.01).The apparent digestibility of dry matter,crude protein and neutral detergent fiber of yaks in groups H and L at different ages increased significantly with age(P<0.01 or P<0.05).The profit of group L was higher than that of group H in all three age groups when yaks were fed with equal amounts of diets.The results showed that 35∶65 of ratio of dietary concentrate to crude in the cold sea⁃son could significantly improve the production performance and economic benefits of Tianzhu white yaks.