Fixed-time post-cervical artificial insemination in weaned sows following buserelin use combined with/without eCG.

Abstract

Fixed-time post-cervical artificial insemination (FTAI) drastically reduces labour requirements and increases the use of boars with higher genetic merit. This study evaluated the efficiency of eCG administration combined with/without the GnRH agonist buserelin for the induction and synchronization of ovulation in weaned sows submitted to FTAI. The sows were allocated into three groups. In the control group, the first artificial insemination was performed at the onset of oestrus and repeated every 24hr. In the eCG+GnRH group, sows received 600IU eCG at weaning and buserelin (10μg) after 86-89hr of eCG, and in the GnRH group, sows received only buserelin after 86-89hr of weaning. The hormone-treated sows received a single FTAI after 30-33hr of buserelin application. All the sows were inseminated with homospermic doses (1.5×109 sperm cells/50ml). The interval between weaning and ovulation was shorter (p<.05) in the eCG+GnRH (133.3hr) and GnRH (135.9hr) groups than the control (141.5hr) group. In the eCG+GnRH group, the sows ovulated earlier (p<.05) than those in the GnRH group (44.5 vs. 48.2hr after buserelin administration). The reproductive performance of GnRH sows was not compromised when only sows exhibiting oestrus at the time of insemination were considered, but lower farrowing rate and smaller litter size were observed in eCG+GnRH sows. The reproductive performance of eCG+GnRH sows was primarily compromised because the insemination was performed outside the optimal time relative to ovulation; therefore, it is advisable to inseminate them before 116-122hr after weaning.