Identification of sow-specific risk factors for late pregnancy loss during the seasonal infertility period in pigs

• Published in: Theriogenology Vol. 72; no. 3; pp. 393 - 400
• Main Authors: Bertoldo, M., Grupen, C.G., Thomson, P.C., Evans, G., Holyoake, P.K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2009; [Oxford]: Butterworth-Heinemann; [New York]: Elsevier Science
• Subjects: Age Factors; Animals; autumn; estrus; farrowing; farrowing rate; Female; fetal death; Fetal Death - etiology; Gestational Age; gilts; herds; Infertility, Female - etiology; Infertility, Female - veterinary; Lactation - physiology; lactation duration; Lactation length; Litter Size; Maternal Age; Parity; parity (reproduction); Parity - physiology; parturition interval; photoperiod; postpartum interval; Pregnancy; pregnancy complications; Pregnancy loss; pregnancy outcome; Pregnancy, Animal; risk assessment; Risk Factors; Seasonal infertility; seasonal variation; Seasons; sows; Species Specificity; Swine - physiology; Wean-to-service interval; weaning; Australia; Seasonal infertility; Parity; Wean-to-service interval; Lactation length; Pregnancy loss
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2009.03.008

Reduced farrowing rates due to late pregnancy loss (LPL) is a manifestation of seasonal infertility in pigs. This study was undertaken to determine sow- and gilt-specific risk factors leading to LPL during the seasonal infertility period (January to April) in Australia. Age at first service was considered to be a major gilt-specific risk factor, whereas sow-specific factors considered included parity, prior wean-to-service interval, prior lactation length, and number of piglets weaned in the lactation period immediately preceding the mating/pregnancy event under scrutiny. Logistic regression analysis of these factors was undertaken on 13,213 animals from three farms (Farms A, B, and C). Age at first service for gilts had an effect on LPL (P < 0.05) on Farm C when compared with that for Farms A and B, with those mated at approximately 220 d having the lowest rate of LPL. For older sows, parity was a factor on Farms A and C (P < 0.001), with the proportion of sows with LPL increasing with increasing parity. When the data from each farm were combined and analyzed, there was a significant farm by WSI interaction, with animals from Farm C being most at-risk for LPL. Sows with shorter lactation periods (P < 0.05) and smaller litters (P < 0.05) at the previous lactation had a greater chance of LPL on all farms. Under the conditions of this study, we were able to identify risk factors for LPL that producers can manipulate during the seasonal infertility period to improve breeding herd productivity.