Interpretive Summary: Insulin-like growth factor-1 is involved in the deteriorated performance of aged laying hens

By: Qian Xin, Victoria Anthony Uyanga, Hongchao Jiao, Jingpeng Zhao, Xiaojuan Wang, Haifang Li, Yunlei Zhou, Hai Lin

The level of insulin-like growth factor 1 (IGF1) in low laying rate hens was significantly decreased in the serum, small white follicles, and dominant follicles. In the hypothalamus and small yellow follicles, the mRNA expression level of estrogen receptor in low laying rate hens was higher than in the medium laying rate hens. Compared with the high laying rate hens, the steroid hormone-synthesis gene, CYP19A1 was significantly decreased in the small white and dominant follicles of medium laying rate hens, as well as in the dominant follicles of low laying rate hens. Additionally, the mRNA expression level of IGF1 receptor was increased in the hypothalamus, pituitary, small white follicles, large white follicles, small yellow follicles, and dominant follicles of low laying rate hens compared to the high laying rate hens. These results suggest that decreased IGF1 in the serum and follicles of laying hens was associated with the reduction in the egg production of aged laying hens. The present study provides novel insights into the endocrine changes in aged laying hens having different egg production performances.