Genetic parameters of protein efficiency in a Swiss Large White pig population

Pork production contributes to environmental pollution through the emission of nitrogen compounds. In addition, pig fattening in Switzerland requires imports of soybean, since the protein requirement of feed cannot be met by domestic plant-protein sources alone. It is therefore desirable to improve protein efficiency, i.e. to achieve a similar protein uptake in the carcass with a lower intake of dietary crude protein, through selective breeding. For a preliminary evaluation of the potential of breeding for higher protein (i.e. nitrogen) efficiency, we used results of previous experiments with protein-reduced feed to estimate genetic parameters of this trait in Swiss Large White pigs. Heritability of protein efficiency in the empty body was estimated at 32 % and in the carcass at 16 %. Positive phenotypic correlations with phosphorus efficiency suggest that breeding for nitrogen efficiency could also increase this trait; however, a slight delay in the growth of protein-efficient pigs might be expected. Further studies are needed to improve the quality of estimates and to obtain information on the underlying genes of protein-efficient pigs.