Bioscientifica Proceedings

Fixed time insemination is a strategy that may facilitate batch management of swine units. After briefly discussing the advantages and disadvantages of the drugs available to induce ovulation in swine and their optimal timing of administration, the reproductive performance of a scheme combining ovulation induction and a single fixed time artificial insemination will be described for gilts and sows. In gilts, this single fixed time insemination regimen includes a GnRH agonist (buserelin) injection at 115-120h after the last feeding of altrenogest, followed 30-33h later by the single insemination. In sows, buserelin is injected 83-89h after weaning and the single fixed time insemination is again performed 30-33h later. Reproductive performance of this scheme was evaluated in two field trials, involving different genetic lines maintained on several farms in several countries, and using females from the same farms bred twice at detected estrus as negative controls. In gilts as well as in multiparous sows, fertility and prolificacy (total born as well as live born) were similar following a single fixed time insemination compared to the negative controls. In these two animal types, this breeding schedule was robust as none of the zootechnical or management factors analyzed interacted with its efficacy. As the number of primiparous sows included in this field trial was limited, further studies will be warranted to establish whether this breeding schedule may be also used in such females (particularly those with short lactations).

Overall, this single fixed time breeding system may be useful for farmers due to reduction in labor and semen costs. In addition, in the longer term, it may facilitate the implementation of techniques that maximize the diffusion of genetic merit from elite boars through use of frozen or sexed semen that need a close synchrony between insemination and ovulation.

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