A meta-analysis of the combined effect of housing and environmental enrichment characteristics on the behaviour and performance of pigs

Abstract To quantify the combined effect of housing conditions and environmental enrichment on the behaviour and performance of pigs, a meta-analysis was performed using information from 45 experiments in 42 published manuscripts. Multiple regression models were applied to evaluate the effects of space allowance per pig ( k -value; m 2 /BW 0.667 ), group size ( n ), floor characteristics (solid, partly, or totally slatted floor), bedding (presence or absence), and the number and presentation sequence of point-source objects (no object, one object, two simultaneous objects, two alternated objects, three or more simultaneous objects or three or more alternated objects) on the general activity, enrichment and object-directed exploratory behaviour, social behaviour, and productive performance. A non-linear relationship between space allowance per pig and time spent sitting and lying was found ( P P k -value and its quadratic term respectively). Total time spent in exploration increased with space allowance per pig when bedding was present ( P P P P P P P P P P P P P P  = 0.10) were present. This information can be utilised in the determination of the general effects of production systems on the welfare of pigs as well as in the development of new production systems.