Dietary protein and fermentable carbohydrates contents influence growth performance and intestinal characteristics in newly weaned pigs

Increasing the dietary amount of fermentable carbohydrates (FC) may counteract the negative effects of protein fermentation in newly weaned piglets. To study this hypothesis, 272 newly weaned piglets were allotted to 4 dietary treatments in a 2×2 factorial arrangement with low and high FC (7.5 and 13.5%) and crude protein (CP, 15 and 22%) content as respective factors. Intestinal histology, enzyme activity, microbiota and fermentation products were determined in 8 pigs per treatment 7 days post-weaning. In the 4 wk experimental period, interactions between dietary CP and FC content were found for feed intake (P=0.022), daily gain (P=0.001), and gain:feed (P=0.033). The high-FC content reduced daily gain by 50 g/d in the low-CP diet, whereas the FC content did not affect growth performance in the high-CP diet. Over the 4 wk experimental period, daily gain (350 g/d) and feed intake (519 g/d) were highest for piglets on the low-CP low-FC diet. The high-FC content resulted in an increase in number of lactobacilli (P=0.047) and a decrease of total coliforms (P=0.06) in the small intestine. It increased the lactic acid content (P=0.08) and reduced the ammonia content (P=0.04) in the small intestine and increased the VFA content in the colon (P=0.009). The reduction in CP content reduced ammonia concentration in the small intestine (P=0.003). We concluded that dietary FC influenced microbial population and fermentation products in the gut. However, this was not reflected in an increased growth performance.