Space allowance determination by considering its coeffect with toy provision on production performance, behavior and physiology for grouped growing pigs

Abstract

Increasing space allowance and enhancing environmental enrichment are two approved solutions to improve pig welfare in modern housing systems, while limited research regarding their interactions could be found. To determine the proper stocking density for growing pigs under China's production conditions, an experiment with a 3 × 2 factorial arrangement (three levels of space allowance × with/without toys) was conducted to evaluate the effects of space allowance and toy provision on the production performance, behavior and physiology of the pigs from the 7th to 13th week of age. Two hundred and sixteen pigs were randomly allocated to pens with the space allowances of 0.5, 0.7 and 0.9 m2/pig, and the group size in each pen was fixed at 18. The results showed that the average daily gain (ADG) and feed conversion ratio (FCR) of the pigs with a space allowance of 0.5 m2/pig significantly decreased (P<0.05), while the average daily feed intake (ADFI) did not differ among the groups. Pigs housed in the lower space allowance of 0.5 m2/pig spent more time fighting and feeder occupying and less time lying and resting (P<0.05). With larger space allowances of 0.7 and 0.9 m2/pig, the surface temperature of the pig body in the middle and later stages after grouping was significantly lower (P<0.05). Toy provision inside the pens effectively decreased the water consumption of pigs at 0.5 m2/pig (P<0.01), while no difference was observed in body surface temperature and saliva cortisol concentration among all groups (P>0.05). Pigs gained more weight with toy provision, and their impact was especially enhanced as floor area decreased. Significant interacting effects of space allowance and toy provision on excessive drinker and feeder occupation and negative social behavior were observed (P<0.05). It is concluded that a higher space allowance is beneficial to weight gain, feed conversion and welfare of growing pigs. Toy provision can greatly reduce the excessive occupying behavior and aggression of pigs in barren and crowded environments, indicating that it could improve the growing pig's welfare by enriching the pen environment when the space allowance is limited at the commercial level. Space allowances ranging from 0.7–0.9 m2/pig with toy provision are suggested for intensively growing pigs under China's production conditions.