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Bulletin No. 17 - Winter 2003
Miscelleanous- No Category
KIRKWOOD R
Understanding and managing seasonal infertility.
Allen D. Leman Swine Conference 2003: 164-168
BO98454
Delayed puberty, prolonged wean-to-estrus intervals and reduction in farrowing rates are the main manifestations of seasonal infertility which primarily affects primiparous sows. Some management practices such as early weaning, improved nutritional quality diet and appropriate boar contact reduce the impact of seasonal infertility. An inadequate nutrient intake during lactation induces several variations in the endocrine system linked to insulin, GH, cortisol and glucagon which globally result in an inappropriate metabolic status for fertility and pregnancy. Care should also be taken to meet the increased energy requirement due to lower temperatures. The importance of the PGE:PGF ratio is also addressed as well as the role of LH in the maintaining of pregnancy and in the helping of ovarian recovery during lactation. Several strategies are proposed to limit seasonal infertility and consist in increasing lactation nutrient intake, reducing the litter size of young sows through cross-fostering, other approaches are injections of gonadotropins or GnRH at breeding in primiparous sows.
