Sow feed intake and lifetime reproductive performance

For many breeding companies, performance testing in maternal lines is generally confined to traits such as average daily gain (ADG), back fat (BF) and perhaps loin muscle depth or area (LMD or LMA), along with litter size traits such as number born alive (NBA) or total born (TB). More sophisticated breeding programs will also accommodate traits associated with sow performance, longevity or piglet survival, using data from traits such as weaning to conception interval, and litter birth or weaning weights, amongst others. Despite these breeding efforts, poor overall reproductive performance, as measured by pigs weaned per sow per year, and poor sow longevity are common problems in modern pig production systems. There are many factors that affect sow reproductive performance and longevity, both environmental and genetic. ... It is possible that the different selection emphasis in maternal compared to terminal lines limits the decline in feed intake under selection relative to that observed in terminal lines. If this were the situation, poorer longevity and reproductive performance are unlikely to solely result from lower voluntary feed intake in maternal lines per se. In fact, the most prolific dam line with the best longevity in the maternal line genetic evaluation program (operated by the National Pork Producers Council, 2000) ate the least feed during lactation but had the same (fixed) feeding level during gestation. In reality, sows are rarely given the opportunity to express appetite because of restricted feeding practices throughout ~65% of their reproductive life. Thus, it is possible that the type of feed restriction throughout the rest of a sows lifetime, which is typically not a function of sow appetite, is the primary key affecting sow longevity and performance, rather than a decline in voluntary feed intake. Generally, we do not know enough about how sow feed intake affects sow longevity and performance. The purpose of this paper is to present information on background research into associations between sow feed intake and reproductive performance. A new project, funded through the Pork CRC, will be outlined.