Considering feed withdrawal from an animal welfare standpoint it may appear that the stress of transport combined with the stress of feed restriction could produce negative affects on the well being of pigs being transported to market. However, Becker et al. Feed withdrawal has a more practical application even if one discounts the possible improvement of pork quality. Feed withdrawal can facilitate the process of evisceration and minimize the chance for microbial contamination of the carcass from lacerations in the gastrointestinal tract. In most cases, feed can practically be withdrawn only from the last load.
Earlier loads are usually on full feed until they are shipped.
To better understand feed withdrawal as a standard production practice these benefits and disadvantages were evaluated as a system in a study conducted at North Carolina State University. Proportion of gastrointestinal tract lacerations Prevalence of Salmonella spp. The barn had 40 pens and the other 4 pens were used to hold the cull pigs and the extreme lightest and heaviest pigs that were excluded from the study. Each pen of 29-32 pigs had pigs of similar minimum and maximum weight with similar variation between pens. Maximum variation within a pen, rather than minimum, allowed the progressive selection of the heaviest third of pigs for slaughter from each pen and simulates the slaughter closeout of a barn where on three occasions the heaviest third of pigs are removed for slaughter.