Factors affecting survival rate of crossbred sows in weaner production

Abstract

Productive life of sows was analyzed by the Cox-Proportional Hazard Model of survival analysis using the program `The Survival Kit' (Ducrocq and Sölkner, 5th World Congress of Genetics Applied to Livestock Production, Guelph, Canada, 22 (1994) 51–52). The influence of the multiplier-farm, litter performance, stage of sow within parity, insemination success, medium weaner price level, live-weight daily gain, leg quality, shape of ham and teat score on productive life were investigated. With the exception of the multiplier-farm, which was included as a random effect, all variables were encoded as `time-dependent covariates' split up according to parity. With the exceptions of ham- and teat scores all effects show a significant influence on productive life of sows. The litter performance and insemination success show the highest effects, followed by the variables of economic conditions. The variables of gilt selection are of least importance. Animals with large body size show an increased risk in the time between third weaning and fifth parity. The greatest influence among the variables of gilt selection has the score given for leg quality. For sows which were assessed as having `slight or temporary defects', the risk of culling in the time between start of productive life and fourth weaning is significantly higher than for the others.