Maternal Capacity, Feed Intake and Body Development in Sows

Selection of a gilt for breeding is the first step in the chain of events that determines sow survival within the herd and ultimately her lifetime of productivity. Unfortunately, selection for improved production attributes can be accompanied by increased sow culling rates (Tholen et al. 1996) and elevated mortality levels in piglets (Knol 2001), which compromises both welfare and profitability. On the sow side, this phenomenon is generally thought to be a consequence of selection altering the balance between nutrient partitioning for maintenance versus productivity, combined with suboptimal nutrition for all requirements of genetically superior sows (Ball et al. 2008), which has consequences for sow phenotype. Several phenotypic studies have identified low lactation feed intake, leg conformation or lameness (Anil et al. 2006; Deen et al. 2007), excessive weight and/or fat loss during lactation (Whittemore 1996), and pre- and post-partum health issues (Hoy 2006) as contributing factors to premature culling of sows, often manifested via their contributions to rebreeding failure. Current literature suggests production traits are relatively minor explanatory variables for sow longevity and lifetime performance, with the possible exception of the association between lean growth and the development of osteochondrosis (Stern et al. 1995). However, key areas in which knowledge of genetic associations are sparse include sow body development post-selection, feed intake attributes of sows and their association with reproductive outcomes and survival between parities. The aim of this paper is to report on results from a specific project developed to investigate these associations in detail from the finisher pig through to the second parity.