PSII-3 - The effects of periodic environmental enrichment on the welfare and production of growing pigs

Abstract: Environmental enrichment is known to decrease damaging behaviours and to improve pigs’ ability to cope with new and stressful conditions. However, challenges such as biosecurity, cost, and labor inputs impede adoption of effective enrichments on-farm. This study investigated the effects of a simple periodic enrichment provided in early (0-9 weeks) and/or late (9-21 weeks) life stages. Twenty-four litters were randomly assigned to two early treatments, Control (C, n=119) and Enriched (E, n=118). One week after birth, E pens were given six pieces of newsprint three days/week that were sprayed with a citrus-scented liquid (Phytozen®), previously shown to reduce aggression. At 9 weeks half of E and C pigs were switched to the opposite treatment producing four treatments in late life: EE, EC, CC, and CE. Growth was recorded throughout the 21 weeks, and movement of groups from farrowing to nursery, and nursery to grow finish (GF), was timed. Lesions were assessed pre- and post-weaning, when moving to GF, and 13, 17, and 19 weeks. Tail bites were scored weekly from 9 to 21 weeks. An economic analysis that considered carcass characteristics and enrichment cost was performed. Data were analyzed using SAS®9.4 with mixed linear models, and Tukeys test was used to separate means. Pigs receiving enrichment during late life had greater average daily gain from 18-21 weeks than all other treatments (EE: 2.00±0.04, CE: 2.07±0.04, CC: 1.96±0.05, EC: 1.98±0.04 kg/day, p=0.019). At 9 weeks, E pigs were easier to handle than C pigs, with faster movement from nursery to GF (E: 212±11, C: 250±11 s, p=0.001). At weaning, E pigs had less severe lesions than C pigs (mean scores, E: 0.51±1.91, C: 1.38±1.86, p=0.004). In late life, EE and CE showed lower lesion scores than CC and EC (mean scores, EE: 2.17 ±1.09, CE: 2.43 ±1.09, CC: 3.50 ±1.08, EC: 3.89 ±1.08, p < 0.001). Throughout GF, EE and CE pigs had lower tail bite scores than CC and EC (mean scores, EE: 1.00 ±1.07, CE: 1.28 ±1.07, CC: 1.51 ±1.07, EC: 1.61 ±1.07, p < 0.001). Pigs provided enrichment during early life had greater lean measurements resulting in $0.89 more per pig. Cost savings due to reduced tail bite damage was predicted but could not be estimated due to low severe tail bite numbers. Access to periodic enrichment improved growth, and reduced aggression, with fewer lesions and less severe tail bite damage during the growing period. Combining periodic enrichment provision with pen checks is recommended to reduce the cost of implementation. Future research on periodic enrichment should focus on timing effects, enrichment type(s) and amount provided. The results support the use of periodic enrichment as a practical way to improve pig welfare and production.