Reproductive performance of sows associated with single, fixed-time insemination programs in commercial farms based on either average herd weaning-to-estrus intervals or postweaning estrous activity

Abstract

ABSTRACT Objective Three separate studies were conducted to determine the effectiveness of adjusting the timing of triptorelin (Ovugel, United Animal Health, Sheridan, IN) administration based on historical weaning-to-estrus intervals (Exp. 1), the occurrence of proestrus (Exp. 2), or the occurrence of estrus (Exp. 3) on reproductive performance of weaned sows. Materials and Methods All studies were conducted on commercial farms in eastern North Carolina during the summer months when both the length and variation associated with weaning-to-estrus intervals for sows were increased. In Exp. 1, sows were assigned at weaning to receive triptorelin at either 96 ± 6 h (n = 196) or 120 ± 6 h (n = 196) followed by a single insemination 22 ± 2 h later. Sows bred once each day of estrus (n = 398) served as the control treatment. In Exp. 2, sows were given boar exposure beginning on d 3 after weaning and at proestrus were assigned to 1 of 2 treatments: (1) control (n = 301), which were bred once each day of detected estrus, or (2) triptorelin (n = 296) followed by a single insemination 22 ± 2 h later. In Exp. 3, sows were given boar exposure beginning on d 3 after weaning, and those detected in estrus on d 4 or 5 were assigned to be bred once each day of estrus (control d 4, n = 98 and control d 5, n = 118) or treated with triptorelin (d 4, n = 97 and d 5, n = 117) followed by a single insemination 22 ± 2 h later. Results and Discussion Reproductive performance was significantly reduced (P ≤ 0.05) when triptorelin was given at a fixed time after weaning irrespective of estrous status compared with the control sows that were bred once each day of estrus (Exp. 1). This was due to the subset of treated sows that were not in estrus when they were bred. In contrast, weaned sows treated with triptorelin at either proestrus or estrus and bred once 22 ± 2 h later had similar reproductive performance (P ≥ 0.63) compared with their counterparts bred once each day of estrus. Implications and Applications Use of either proestrus or estrus as the criterion for intravaginal administration of triptorelin and the subsequent fixed-time AI in herds with extended or variable weaning-to-estrus intervals was effective in terms of maintaining reproductive performance equivalent to conventional AI strategies.