Kisspeptin in the early postpartum of the dairy cow.

Recently, a new molecule, kisspeptin (Kp), and in particular Kisspeptin 10 (Kp10), was implicated in stimulating the hypothalamic–pituitary–gonadal axis. The aim of this study was to evaluate circulating Kp10 levels in the early post–partum period of the dairy cow. Blood samples were collected from 40 dairy cows, at 10 (T10), 12 (T12), 14 (T14) and 16 (T16) days after calving. Progesterone (P4) levels were evaluated using ELISA, and levels of oestrogens (E2) and Kp were evaluated using a radio‐immunologic method. After an initial plateau, Kp10 significantly increased at T14 and decreased at T16. The P4 and E2 mean serum values remained in the physiological range. It is likely that Kp10 enhanced hypothalamic GnRH release as well as pituitary gonadotropin secretion, thus promoting follicular growth and the increase in E2 levels, which might have further enhanced Kp10 release through a positive feedback loop. To our best knowledge, this is the first report on the range of Kp10 blood concentration during the early post–partum period in the dairy cow. The results of our study will increase our current understanding of the complex neuro‐endocrine crosstalk underlying the resumption of ovarian cyclicity in the dairy cow.