Impact of different dietary fibre levels on the roughage resistance of the Dahe black pig

To investigate the effects and molecular mechanism of different levels of dietary fibre (Chinese milk vetch) on Dahe black and Duroc × (Landrace × Yorkshire) (DLY) pigs, 54 of each type of pig were selected and fed diets that contained 3.5%, 5.5% and 7.5% levels of fibre in the growing (30–60 kg) and fattening stages (60–120 kg). The production performance, serum physicochemical indices, nutrient digestibility, the amylase activity in the small intestine, contents of the muscle crude protein and ether extract, and the levels of transcription of the PRKAG3 and Fsp27 genes were determined. The production performance of the Dahe black pigs with a 5.5% level of dietary fibre was significantly higher than those with dietary fibre levels of 3.5% and 7.5%. A diet high in fibre also significantly affected the production performance of the DLY pigs. The apparent digestibility of the nutrients decreased with an increase in the dietary fibre level, and the Dahe black pigs appeared to more effectively digest the dietary fibre than the DLY pigs. The serum physicochemical indices, amylase activity, and the expression levels of the PRKAG3 and Fsp27 genes from the Dahe black pigs were significantly higher than those of the DLY pigs, and the intramuscular fat content of the Dahe black pigs fed a high fibre diet was significantly higher than that of the DLY pigs. The dietary fibre levels of 5.5% and 7.5% did not affect the production performance of the Dahe black pigs during the 30–120 kg period, but they significantly reduced the production performance of the DLY pigs. The Dahe black pigs were evidently tolerant to high amounts of fibre when fed a high fibre diet.