Dynamic changes of reproductive hormones in normal pregnancy of blue fox during estrus insemination

Reproductive hormones are the key factors that regulate animal reproduction,so it is crucial to explore the levels of these reproductive hormones and their changes in the blue foxes during normal pregnancy. In this study,26 blue foxes were tested for reproductive hormones on the 1 st,20 th,35 th,and 50 th days of normal pregnancy during the peak estrus insemination in the breeding season to clarify the role of reproductive hormones in the blue fox during the peak estrus insemination. The normal levels of follicle-stimulating hormone（FSH）,luteinizing hormone（LH）,estradiol（E2）,progesterone（P）,and prolactin（PRL）and their changing patterns were detected. The results of the study showed that the reproductive hormones FSH and LH declined rapidly from day 1 to day 20 during pregnancy but remained at a constant level after day 20. Estradiol and P showed a significant downward trend throughout the pregnancy,while PRL showed a step-growth trend.