Effect of temporary straw bedding on pigs' behaviour, performance, cortisol and meat quality

The effect of temporary straw bedding for a period of 6, 4, or 2 weeks before slaughter was studied on pigs' performance, behaviour, cortisol concentration, intermediary metabolism, and meat quality. Pigs were barren housed on slatted concrete floors during growth and allocated to one of following four treatments (T): straw bedding during 6 weeks (6wk), 4 weeks (4wk), 2 weeks (2wk) before slaughter, and a control treatment without straw bedding (0wk). This experiment was replicated six times but in two replicates T6wk could not be included. A total of 220 pigs were involved, of which 132 served as focal animals for behavioural observations. The meat quality of 110 of these pigs was measured and 48 pigs were also sampled for salivary cortisol. The pigs of T6wk and T4wk had a higher average daily weight gain after 2 weeks of straw bedding, whereas no differences in feed intake or feed conversion were observed over the whole test period, nor effects on carcass weight or back fat thickness. The weekly observation of the focal animals during 5 min showed that straw provision decreased pen manipulation (P = 0.001) and pen mate manipulation (P = 0.0001). The time pigs spent on postures and specific behaviours like eating, biting and fighting was not different between treatments. Saliva samples, taken every 2 weeks, revealed no cortisol concentration differences between the treatments. No differences in plasma cortisol, glucose, lactate, or NEFA concentrations were found at slaughter. The concentration of creatine kinase tended to be lower in pigs of T6wk compared to pigs of T0wk (P = 0.07). No treatment effects on skin lesions of the front, middle, and hind regions were observed in the slaughter line. Finally, meat quality measurements in the longissimus dorsi muscle revealed no differences in pH 45 min post-mortem or in pH, electrical conductivity, colour, and water-holding capacity 24 h post-mortem. It is concluded that straw redirects the pigs' behaviour from pen manipulation and pen mate manipulation to straw manipulation after straw provision, but that there are no or only minor differences in carcass quality, cortisol concentrations, intermediary metabolites, and meat quality of pigs given a temporary straw bedding of 6, 4, or 2 weeks before slaughter or no straw. (c) 2005 Elsevier B.V. All rights reserved.