Impact of increasing market pig weights in North America: a comprehensive review

The North American swine industry is shifting towards raising pigs to heavier weights, partly due to the potential for higher profitability for pork processors. However, producers may incur losses due to feed and transportation costs associated with heavy-weight pigs. In some cases, these animals can fall outside grid-based grading specifications, resulting in discounts for carcasses that are too heavy or too lean/too fat. Furthermore, increasing weight raises concerns regarding nutritional requirements, feed efficiency, environmental sustainability, welfare issues, carcass composition, chilling rate, meat quality, and implications for genomic selection. Variation exists for growth performance traits and carcass composition across genotypes. In this review, we summarise the biological, physiological, and genetic mechanisms underlying the effect of increasing weight in contemporary pig production. A comprehensive understanding of animal performance, animal welfare, carcass traits and genetic regulations in heavy-weight pigs will be significant for refining breeding goals, precision feeding strategies and handling practices.