Effects of Dietary Betaine on Production Perform- ance, Egg Quality and Serum Biochemical Indexes of Layers under Heat Stress Condition

摘要

[Objective]This experiment was conducted to study the effects of dietary betaine on performance,egg quality and serum biochemical parameters of laying hens under heat stress condition. [Method]A total of 600 22-week-old commercial Roman laying hens were randomly divided into five groups,with eight replicates in each group and 15 hens in each replicate. Group I was taken as the positive control group,and laying hens in group I were fed with basal diets in normal thermal environment. Temperature humidity index of group I was between 64. 9 and 68. 9. Group II was taken as the negative control group,and laying hens in group II were fed with basal diets under heat stress condition. Temperature humidity index of group II was higher than 72. Laying hens in groups III-V were fed with basal diets supplemented with 200,400 and 600 mg/kg betaine under heat stress condition respectively,and temperature humidity indexes in groups III-V were all higher than 72. The experiment lasted for 14 weeks. [Results]Results showed that there were no significant differences in average daily feed intake,feed egg ratio and broken egg rate among different test groups( P > 0. 05). Hen-housed laying rate,hen-housed egg yield,serum total protein( TP) content and serum alkaline phosphatase( AKP) activity in group II were significantly lower than those in group I( P < 0. 05). However,activities of glutamic-oxalacetic transaminase( GOT),creatine kinase( CK) and glutamic-pyruvic transaminase( GPT) in group II were significantly higher than those in group I( P < 0. 05). Hen-housed laying rate,hen-housed egg yield and serum TP content in group IV were significantly higher than those in group II( P < 0. 05). Hen-housed egg yield,serum TP content and serum albumin( ALB) content in group V were significantly higher than those in group II( P < 0. 05). Activities of serum CK and GPT in groups IV and V were significantly lower than those in group II( P < 0. 05),serum triglyceride( TG) content in group V was significantly lower than that in group II( P < 0. 05).[Conclusion]Metabolism and physiological function of laying hens could be affected by heat stress,and which caused a decline in performance. Adding of dietary betaine in diets could improve hen-housed egg production and hen-housed laying rate,which could also improve the health of laying hens under heat stress condition. The appropriate dietary adding content of betaine was 400 mg/kg.