Selecting for feed efficiency in pigs and its effect on growth performance, nutrient digestibility and carcass characteristics
With a higher demand for protein and a limited supply of feed, the ideal animal with low inputs costs and high-quality output is sought after. This is termed feed efficiency (FE) and it measures the animal’s ability to turn feed into an edible product with the least amount of resources including environmental impacts. Feed accounts for about 60 - 70% of the total cost of production and with the cost of feed at a steady increase, it would be profitable to improve the pig’s efficiency. The goals for researchers are to find methods to produce more food with less input and environmental impacts while ensuring animal welfare. Genetic selection programs have focused on selecting FE traits such as feed conversion ratio (FCR) and residual feed intake (RFI). Improving FE can be difficult to estimate due to its variation from animal to animal as well as the many biological factors involved. The impact of individual biological factors on FE is important to evaluate in research to help predict selection for FE outcomes including negative outcomes. Our study was conducted to determine the effect of selecting for feed efficiency using estimated breeding value (EBV) for FCR on digestibility, growth performance, and carcass characteristics of two Large White lines. High feed efficient (HFE) pigs consumed less feed (P < 0.05), had thinner fat depth (P < 0.05,) and had greater loin depth (P < 0.05) than low feed efficient (LFE) pigs. In addition, HFE pigs had a significantly higher apparent total tract digestibility (ATTD) of calcium (P = 0.05) and a tendency for a higher ATTD for crude protein (P = 0.06), and phosphorous (P = 0.10) compared to LFE pigs. In conclusion, pigs can be selected for high feed efficiency and as a result, will consume less feed and produce leaner carcass without affecting growth performance (ADG). It is possible that the feed intake and nutrient digestibility can explain part of the animal-to-animal variation. However, the underlying biological mechanisms as well as any negative effects of selecting for FE requires investigation.
Feed efficiency, Feed conversion ratio, Apparent total tract digestibility, Growth performance, Carcass characteristics