AGBU Pig Genetics Workshop – October 2010 51 Sow development, reproductive performance and longevity Kim L Bunter and Craig R G Lewis Animal Genetics and Breeding Unit (AGBU), University of New England, Armidale, NSW, 2351, AGBU is a joint venture between Industry and Investment New South Wales and the University of New England. Introduction Selection of a gilt for breeding is the first step in the chain of events that ultimately determines 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 productivity as well as 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 (Ball et al., 2008) to meet requirements of genetically superior sows. However, it is not well known how attributes at selection (individual phenotype) and genetic potential (EBV) are associated with subsequent body development of the sow, particularly since maternal development occurs concurrently (in competition) with reproduction. This has shifted some research emphasis to investigating traits like lactation intake, whereas sow development prior to lactation is ongoing throughout reproductive cycles (Figure 1). • Genetic potential • Requirements for performance Selection • Litter size • Lactation performance Farrowing • Health and body condition • Management decisions Rebreeding vs Culling Lactation intake Sow development End SPL Figure 1. Connections exist between sow body development, reproductive performance and sow productive life (SPL) 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. 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 workshop paper is to briefly