Abstract
The experiment was carried out to examine the growth, behaviour, and welfare response of weaning pigs to environmental enrichment from d 1 to d 28 after weaning. A total of 240 weaning pigs with average initial body weight (BW) 6.56 ± 0.17 kg were randomly allotted to one of the four treatments on the basis of initial BW. A completely randomized design was used to conduct this study. There were ten pigs per pen, with 6 replicates for each treatment. The experimental treatments were control, EE-1 (inclusion of play object until one week after weaning), EE-2 (inclusion of play object until two weeks after weaning), and EE-4 (inclusion of play object until four weeks after weaning). The pigs raised the EE-2 and EE-4 treatments had greater average daily gain (p = 0.002). The average daily feed intake (p = 0.016) was increased in the EE-2 treatment in phase 1. The pigs in the EE-4 treatment had greater average daily gain (p = 0.039) and average daily feed intake (p = 0.030) in phase 2 than pigs raised in the control treatment, and overall (average daily gain: p = 0.006, average daily feed intake: p = 0.014). The pigs under enriched environment treatments (EE-2 and EE-4) decreased BW uniformity in phase 1 (p = 0.006) and phase 2 (p < 0.001) than pigs in the control treatment. The incidence of diarrhea was lowered (p < 0.001) in early phase 1 (d 7 after weaning) under environmental enrichment treatments (EE-2 and EE-4). Behaviour traits exhibited reduced agonistic behaviour, such as biting (p = 0.018), tail biting (p = 0.001), and ear biting (p = 0.016) under environmental enrichment treatments (EE-2 and EE-4) in phase 1. The skin lesion score was reduced (p = 0.015) in the EE-4 treatment in phase 1. Hair cortisol was reduced in the EE-4 treatment (p = 0.032) at the end of phase 2, however, there were no significant differences in salivary cortisol concentration. These findings demonstrated beneficial effects on growth, group uniformity, behaviour, incidence of diarrhea, skin lesions, and concentration of hair cortisol through exposure to environmental enrichment after weaning.