Floor space allowance is a complex issue in swine production, and one that is critical for both economic and welfare reasons. There is currently a significant body of research on the effects of space allowances in grow-finish pigs (Edwards et al., 1988, Ekkel et al., 2003, McGlone and Newby, 1994, Pastorelli et al., 2006). The values established have been used as the basis for space allowance requirements for nursery pigs (NFACC, 2014). Relatively little is known regarding the effects of stocking density on nursery pigs (EFSA, 2005, Gonyou et al., 2006). Because nursery pigs are commonly observed to overlie one-another when resting, the k value which is appropriate for finishing pigs may in fact overestimate the space requirements of nursery pigs.
Although individual pig growth declines at higher densities, overall farm productivity can increase as higher numbers of pigs are produced per unit of building space (Kornegay and Knotter, 1984). Thus, the economic optimum for space may be lower than that for achieving maximum growth rate. However, stocking at higher densities can also negatively affect the welfare of the pig, with risk of immune suppression and increased disease susceptibility (Turner et al., 2000) or restriction of pigs’ ability to express normal behaviour.
It has been recommended that evaluations of space requirements for pigs should include changes in the behaviour of pigs, and establish the welfare relevance of such changes, to support calculation of space allowances based on what space an animal needs rather than solely on the basis of production performance (Ekkel et al., 2003). Group size and seasonal differences should also be evaluated or controlled for as these factors may also influence growth and behavior (Hyunh et al., 2005, Spoolder et al., 2012),. It has been suggested that larger groups of pigs may require less space, due to the sharing of free space (McGlone and Newby, 1994). However, this has also been disputed (Street and Gonyou, 2008).
This study will examine measures of productivity and welfare in nursery pigs, and will include an economic analysis comparing space allowance treatments above and below the Code requirement of k= 0.0335.
Source: Prairie swine Center