Genetic and environmental effects on piglet survival and maternal behaviour of the farrowing sow

Abstract

There is growing external pressure to abolish the farrowing crate, however alternative farrowing systems need to equal or surpass the performance (i.e. piglet survival) of more restrictive systems. In order to achieve consistent improvement in piglet survival genetic selection strategies targeting specific survival traits could be used. One of the key components of survival in alternative, loose-housed farrowing systems is maternal behaviour and understanding the characteristics of sows that influence survival in such environments should be an essential component when developing new breeding indices. In this study 65 gilts and their piglets (757) from two genetic selection lines, High postnatal Survival (HS) or Control (C), were studied in both indoor loose-housed and outdoor farrowing systems. The influence of genetics and environment on piglet survival and maternal characteristics was studied. Genotype affected total mortality at a piglet level in the outdoor system (C: 17.90% (±3.23) vs. HS: 12.21% (±3.46) W 1 = 3.60, P = 0.058), but there was no effect in the indoor loose-housed environment (C: 12.29% (±2.69) vs. HS: 14.86% (±3.18) W 1 = 0.07, P = 0.797). Genotype influenced maternal characteristics, with C gilts in both environments being significantly more likely to crush their piglets when changing posture during farrowing (Mean deviance ratio 1,62 = 47.25, P = 0.002). High Survival gilts in the indoor environment were aggressive towards their offspring, and were the only genotype to display savaging behaviour (Mean deviance ratio 1,62 = 64.90, P < 0.001). This suggests a genetic effect on environmental sensitivity and thus, in order to make effective improvements it is important to estimate genetic parameters (both behavioural and physiological) under the conditions in which the animals will be kept.