Effect of biostimulation on the duration of postpartum anestrus in hair sheep: A review

Objective: To describe the effect of biostimulation, understood as the male effect and suckling management, on the reestablishment of ovarian activity during the postpartum anestrus in hair sheep. Design/methodology/approach: A comprehensive review and analysis of scientific literature were conducted, focusing primarily on the biostimulatory effects of the male and the influence of suckling on reproductive activity during the postpartum anestrus in ewes. Results: Suckling during the postpartum period induces a marked inhibition of reproductive activity. The sudden introduction of the male into pens containing lactating females elicits a positive stimulus for the reactivation of ovarian activity during postpartum anestrus. The abrupt exposure of ewes to the male following parturition, coupled with the limitation of mother-lamb contact during the postpartum period, significantly reduces the interval between parturition and first ovulation in hair sheep. Study limitations/implications: There is limited research on the physiological effect of the male during postpartum anestrus and its association with the resumption of ovarian function in ewes, as well as its potential interactions with the inhibitory effect of suckling on reproductive activity. Findings/conclusions: The positive stimulus reflected by an increase in the pulsatile secretion of luteinizing hormone (LH) exerted by the male during postpartum anestrus is more effective, can be prolonged, and may induce ovulation when suckling is managed. Specifically, restricting contact between the ewe and the lamb for a defined period helps mitigate the negative effect, preventing the suppression of LH pulsatility. According to current literature, controlled suckling is among the most effective strategies to shorten the parturition-to-first-ovulation interval in hair sheep.