Indicators of piglet survival in an outdoor farrowing system

Pre-weaning piglet mortality continues to be a major welfare and economic concern. In outdoor farrowing systems, there is a particular need to broaden breeding goals by incorporating selection for piglet survival to improve both productivity and welfare. This study aimed to identify behavioural and physiological survival indicators that are influential in outdoor systems and that could provide additional information for use when selecting for piglet survival. Data were collected from 511 piglets from Large White × Landrace × Duroc sows and Generalised Linear Mixed Models determined which indicators were most important for piglet survival in an outdoor system. With respect to prenatal mortality (surviving vs. stillborn piglets) high ponderal index (P < 0.001) or body mass index (P < 0.001) in conjunction with being born earlier in the farrowing birth order (P < 0.001) were the most important survival indicators. Birth weight (P < 0.001) and rectal temperature 1 h after birth (P = 0.032) were the most significant postnatal survival indicators. However survival indicators identified as important in indoor, conventional farrowing crates, such as landmark behaviours (latency to reach the udder, a teat and to suckle colostrum), were not influential in this system. These results highlight the importance of studying potential indicators of survival in alternative farrowing systems to the farrowing crate.