Fertility programs for lactating dairy cows: a novel Presynch + Timed AI program (Double E-Synch) produces similar ovarian dynamics, synchronization, and fertility as Double-Ovsynch.

Fertility programs were implemented for the first postpartum timed-AI (TAI) in 800 (primiparous and multiparous) lactating dairy cows, evaluating 2 presynchronization (presynch) strategies and 2 TAI protocols, in a 2 × 2 factorial arrangement. Weekly, cows were enrolled into 1 of 4 groups (Ovs+Ovs [Double-Ovsynch], Ovs+OvsP4/E2, PreP4/E2+Ovs and PreP4/E2+OvsP4/E2 [Double E-Synch). On d -17 (34 ± 3 d in milk), the Ovs presynch was initiated with 10 µg of buserelin acetate (GnRH), and cows received 0.

Induction of puberty induction of ovulation using steroid hormones in beef heifers: a comprehensive review.

This review elucidates the physiological and endocrinological processes intrinsic to puberty and ovulation induction protocols in and beef heifers. Puberty is a complex physiological event involving gonadotropic and metabolic changes that lead to sexual maturity, first ovulation, and regular reproductive cycles, enabling females to reproduce. Exposure to progesterone-based hormonal protocols, with or without additional hormones, can reduce the age at first ovulation and improve sexual maturity through stimuli in the hypothalamus-pituitary-gonadal (HPG) axis and uterine development.