Struggling to survive: early life challenges in relation to the backtest in pigs

Summary

Intensively reared piglets may face many early life challenges and these may affect behavior. The objective of this study was to examine the relationship between piglets’ early life circumstances and their behavioral response in a backtest. Hereto, 992 piglets of 14 d of age were subjected to a backtest, in which they were 1 min restrained in supine position. The number of struggles in the backtest was assessed in relation to data on ADG, BW, BW relative to litter mates, teat order, litter size, and health. Piglets that had a lower ADG from birth till the test day were struggling more (b = -2.4 g ADG/struggle; P = 0.03). Also piglets with a lower BW at 14 d of age tended to respond more actively in the backtest (b = -0.03 kg/struggle; P = 0.08). The response to the backtest was unrelated to ADG from birth till weaning, birth weight, weaning weight, teat order, litter size, and health. ADG and BW were unrelated to the variation of backtest responses within the litter. The weak though significant relationship suggest that smaller slower growing piglets more actively respond to a challenge, either because piglets born with such a behavioral response were better able to survive, or because piglets adapted their behavioral response to their physical condition.