Effect of cereal fermentation and carbohydrase supplementation on growth, nutrient digestibility and intestinal microbiota in liquid-fed grow-finishing pigs

This study aimed to determine the impact of fermenting the cereal fraction of the diet (C(ferm)) and enzyme supplementation (ENZ) on the bacterial composition of the feed, nutrient digestibility, pig growth, feed efficiency (FE), intestinal volatile fatty acid (VFA) concentrations and intestinal microbiota composition. A total of 252 grow-finisher pigs (~ 40.4 kg; 7 pigs/pen) were randomly allocated to 4 diets in a 2 × 2 factorial arrangement for 55d. The diets were: (1) fresh liquid feed (Fresh); (2) C(ferm) liquid feed (Ferm); (3) Fresh + ENZ and (4) Ferm + ENZ. C(ferm) increased total tract nutrient digestibility, reduced caecal butyrate and propionate concentrations, and increased average daily gain (ADG). ENZ increased ileal and total tract nutrient digestibility, reduced caecal isobutyrate and propionate concentrations, and improved FE. Bacterial taxa positively correlated with pig growth (Lactobacillus kisonensis in the ileum and Roseburia faecis in the caecum) were more abundant in pigs fed ENZ diets, whereas most of the ileal bacterial taxa negatively correlated with growth (Megasphaera, Bifidobacterium and Streptococcus) had lower abundance in pigs fed C(ferm) diets. In conclusion, C(ferm) increased ADG and ENZ improved FE, with these improvements possibly mediated by increased nutrient digestibility, and beneficial modulation of the intestinal microbiota.