Risk factors for stillbirths in two swine farms in the south of Brazil

We evaluated stillbirth risk factors in two commercial swine farms of the Rio Grande do Sul State (south of Brazil). The study was conducted during I month in Farm A and during 2 months in Farm B, both during 1999. Data for all farrowings that occurred during the study period were recorded ( 101 for Farm A and 373 for Farm B), without interference in the farm management. In Farm A, 39% of all litters born during the period of interest had stillborn piglets and the stillburn risk for piglets was 12%. In Farm B, 25% of all litters had stillborn piglets whereas the stillborn risk was 2%. Variables considered as potential risk factors for stillbirths were: parity (1, 2-3, 4+); breed (purebred or crossbred); sow body-condition (normal or fat); use of oxytocin during parturition (yes or no); obstetric intervention through vaginal palpation (yes or no); farrowing duration (<4 or greater than or equal to4 h); mummified fetuses (yes or no); total litter size (<12 or greater than or equal to12 piglets); and litter birth weight (<11 or greater than or equal to 11 kg). All stillborn piglets had their classification validated by necropsy. In multivariable logistic-regressions, the cases were the litters having at least one stillborn piglet. In Farm A, litters having at least 12 pigs and in which oxytocin was used during the parturition had 20.8-times-higher odds of stillborn occurrence. In Farm B, litters from sows having parity greater than or equal to4 had 2.2-times-higher odds of stillborn occurrence than litters from parity 2 to 3 females, litters having greater than or equal to 12 pigs had 2.0-times-higher odds of a stillborn piglet than smaller litters and farrowings in which vaginal palpation was performed had 8.0-times-higher odds. Farrowing room management to minimize stillborn risk should target higher-parity females, large litters and optimization of practices of obstetric interventions. (C) 2002 Elsevier Science B.V. All rights reserved.