Large bowel fermentation of maize or sorghum–acorn diets fed as a different source of carbohydrates to Landrace and Iberian pigs

Abstract

Twenty-four finishing pigs (twelve Iberian and twelve Landrace) were used in a growing and slaughtering experiment. Animals were fed two diets differing in their ingredients, maize (diet C) or sorghum–acorn (diet A). At an average weight of 107·0 kg pigs were slaughtered and hindgut digesta sampled to study the effect of breed and diet on large bowel fermentation. Flows of digesta to the hindgut compartment were estimated based on an indigestible flow marker (Cr2O3) and were higher in Iberian than in Landrace pigs (P<0·001), and higher in animals fed diet A than diet C (P=0·07). The higher flows in Iberian pigs were mainly associated with a higher voluntary feed intake (3·50v.2·70 kg/d,P<0·01) and lower ileal digestibility of NSP (−12·8v.47·8,P<0·01). Differences between diets were mainly associated with a lower ileal digestibility of starch from diet A (89·2v.96·9%,P=0·06), although no differences in the resistant starch content were observedin vitro. Fermentation of different carbohydrates through the large bowel showed that NSP-glucose had lower digestibility in Iberian than in Landrace pigs (62·5v.94·2%,P<0·001), but no differences were observed in starch, or other NSP-fibre fractions (arabinose, xylose and galactose). The type and amount of carbohydrates reaching the large bowel were related to the diet but also to breed, and promoted differences in the fermentative activity associated with different volatile fatty acid patterns and changes in microbial enzymic activity.