Effects of Different Protein and Energy Levels of Diets on Growth Performance,Nutrient Apparent Digestibility and Serum Biochemical Indexes of Fattening Yaks in Shelter Feeding
This study aimed to investigate the effects of different protein and energy levels of diets on growth performance,nutrient apparent digestibility and serum biochemical indexes of fattening yaks in shelter feeding.A total of 90 male yaks with good body condition and similar age and body weight(180.00±11.67)kg were randomly divided into 9 groups with 10 yaks per group.Three levels were set for each factor,namely 3 protein levels of low(12.5％),medium(15.5％),and high(18.5％),as well as 3 comprehensive net energy levels of low(6.5 MJ/kg),medium(7.5 MJ/kg),and high(8.5 MJ/kg),9 different total mixed diets(TMR)were designed with 3 protein levels multiplied by 3 energy levels,with each TMR fed to 1 experimental group in the pretest period of 20 days and the formal trial period of 90 days.Results showed as follows:1)protein level had no significant effect on growth performance indexes(P＞0.05),while net energy level had significant effects on the total weight gain(TWG)and average daily gain(ADG)(P＜0.05),and had an extremely sig-nificant effect on ratio of feed to gain(F/G)(P＜0.01);the interaction of protein and net energy level had significant effects on TWG,ADG and F/G(P＜0.01).2)Protein level had extremely significant effects on the digestibility of crude protein(CP)and Ash(P＜0.01),and had significant effects on the digestibility of acid detergent fiber(ADF),neutral detergent fiber(NDF)and crude fiber(CF)(P＜0.05);net energy level had a significant effect on the digestibility of Ash(P＜0.05);the interaction of 2 factors had significant effects on the digestibility of dry matter(DM)and Ash(P＜0.05).3)Protein level had an extremely significant effect on the contents of serum urea nitrogen(UN)(P＜0.01),and had significant effects on the content of phosphate(P)in serum(P＜0.05);net energy level had extremely significant effects on the contents of total protein(TP),albumin(ALB),triglyceride(TG)and total cholesterol(TC)(P＜0.01)and a significant effect on total bile acid(TBA)content in serum(P＜0.05);the interaction of 2 factors had extremely signifi-cant effects on the alkaline phosphatase(ALP)activity and UN content(P＜0.01),and had significant effects on the content of creatinine(CRE)and P(P＜0.05).In conclusion,the effects of comprehensive net energy level on growth performance of yaks is greater than that of protein level,while the effect of protein level on nu-trient apparent digestibility is greater than that of energy level.Under the conditions of this study,with the diet-ary comprehensive net energy level of 8.5 MJ/kg and protein level of 15.5％,the growth performance of fatte-ning yaks in shelter feeding is the best.[Chinese Journal of Animal Nutrition,2024,36(3):1698-1712]
yakshelter feedingcentralized fatteninggrowth performancenutrient apparent digestibilityserum biochemical index
万方数据
维普
