Effects of dietary betaine supplementation on reproductive performance of Tibetan chickens and serum lipid metabolism-related indexes of its offspring.

The purpose of this study was to investigate the effects of dietary betaine supplementation on reproductive axis-related hormones, relative gene expression levels, offspring growth performance and lipid metabolism in Tibetan chickens. A total of 180 30-week-old laying Tibetan chickens were randomly assigned to three dietary treatments with six replicates per treatment (10 hens per replicate). The control diet consisted of corn-soybean meal, whereas experimental groups 1 and 2 received diets containing 1 g/kg and 3 g/kg betaine supplementation, respectively. After one week of environmental adaptation, the formal experiment proceeded for seven consecutive weeks. The results showed that betaine significantly increased the number of large white follicles and total follicles of Tibetan chickens, and up-regulated the gonadotropin-releasing hormone mRNA expression in the hypothalamus of Tibetan chickens (p < 0.05). The content of follicle-stimulating hormone and luteinizing hormone in serum of 3 g/kg group was significantly improved by the betaine compared with other groups (p < 0.05). The relative gene expression of for estrogen receptor β, follicle-stimulating hormone receptor and luteinizing hormone receptor in the ovary was significantly up-regulated in the 3 g/kg group compared with the control group (p < 0.05). Betaine significantly promoted hatching weight, liver index and the content of total cholesterol in the serum of the Tibetan chicken offspring (p < 0.05). In conclusion, the dietary supplement betaine can promote the reproductive performance of Tibetan chickens and regulate hepatic lipid metabolism in offspring of Tibetan chickens.