Digestive efficiency is a heritable trait to further improve feed efficiency in pigs

The use of diets with dietary fibres from alternative feedstuffs less digestible for pigs is a solution considered to limit the impact of increased feed costs on pig production. This study aimed at determining the impact of an alternative diet with fibres on individual digestive efficiency coefficients, and to estimate their heritabilities and genetic correlations with other production traits. A total of 480 Large White pigs were fed a high fibre diet (FD) and 547 of their sibs were fed a conventional diet (CO). For each animal, digestibility coefficients (DC) of energy, organic matter, and nitrogen were predicted from faeces samples analysed with near infrared spectrophotometry. Individual daily feed intake (DFI), average daily gain (ADG), feed conversion ratio (FCR) were recorded as well as lean mean percentage (LMP), carcass yield (CY) and meat quality traits. The FD pigs had significantly lower DC than CO pigs (-5 to 6 points). The DC were moderately to highly heritable, with heritabilities ranging from 0.41±0.14 to 0.50±0.15 in CO, and from 0.62±0.17 to 0.70±0.17 in FD. Genetic correlations between DC and ADG (from -0.65 to -0.52), FCR (from -0.75 to -0.33), and DFI (from -0.83 to -0.57) were high and negative in both diets. The DC were slightly unfavourably correlated with CY (from -0.24 to -0.11) and favourably correlated with LMP (from 0.03 to 0.29). Genetic correlations were generally unfavourable with meat quality traits (from -0.75 to 0.09). Genetic correlations of DC between diets were close to 1, so no interaction between feed and genetics could be evidenced for these traits. To conclude, DC measured in farm conditions are interesting criteria for selection to account for animal digestive capacity, due to moderate to high heritabilities and high genetic correlations with FCR. However, according to these first results, it would have to be selected together with carcass yield and meat quality to avoid adverse genetic trends on the latter traits.