Early human contact and housing for pigs - part 3: ability to cope with the environment

Early experiences can have long-term impacts on stress adaptability. This paper is the last of three in a series on early experiences and stress in pigs, and reports on the effects of early human contact and housing on the ability of pigs to cope with their general environment. Using a 2 × 2 factorial design, 48 litters of pigs were reared in either a farrowing crate (FC) or a loose farrowing pen (LP; PigSAFE pen) which was larger, more physically complex and allowed the sow to move freely. Piglets were provided with either routine contact from stockpeople (C), or routine contact plus regular opportunities for positive human contact (+HC) involving 5 min of scratching, patting and stroking imposed to the litter 5 days/week from 0 to 4 weeks of age. At 4 weeks of age (preweaning), C piglets that were reared in FC had considerably lower concentrations of serum brain-derived neurotrophic factor (BDNF) than piglets from the other treatment combinations. Compared to C pigs, +HC pigs had fewer injuries at 4 weeks of age. There were no clear effects of human contact on BDNF concentrations or injuries after weaning, or on basal cortisol or immunoglobulin-A concentrations, behavioural time budgets, tear staining, growth, or piglet survival. Compared to FC piglets, LP piglets showed more play behaviour and interactions with the dam and less repetitive nosing towards pen mates during lactation. There was no evidence that early housing affected pigs' behavioural time budgets or physiology after weaning. Tear staining severity was greater in LP piglets at 4 weeks of age, but this may have been associated with the higher growth rates of LP piglets preweaning. There was no effect of lactation housing on growth after weaning. Preweaning piglet mortality was higher in the loose system. The findings on BDNF concentrations, injuries and play behaviour suggest improved welfare during the treatment period in +HC and LP piglets compared to C and FC piglets, respectively. These results together with those from the other papers in this series indicate that positive human interaction early in life promotes stress adaptability in pigs. Furthermore, while the farrowing crate environment deprives piglets of opportunities for play behaviour and sow interaction, there was no evidence that rearing in crates negatively affected pig welfare or stress resilience after weaning. Whether these findings are specific to the two housing systems studied here, or can be generalised to other housing designs, warrants further research.