The effects of emulsifier and β-mannanase supplementation in diets with different dietary energy levels in grower pigs

The present study investigated the effects of dietary energy levels with β-mannanase (βM) and emulsifier (EM) supplementation on grower pigs. A total of 192 pigs (Landrace × Yorkshire × Duroc) with an average initial body weight of 22.78±1.06 kg were randomly assigned to 8 treatments with 6 replicates (4 pigs per pen). The experiment lasted 35 days (phase 1, d 1–21; phase 2, d 22–35) and followed a 2×2×2 factorial design with metabolizable energy levels (3,350 and 3,250 kcal/kg), βM supplementation (- and +0.05%), and EM supplementation (- and +0.05%). There was a tendency toward an interaction between EM and βM supplementation during phase 1 on fecal microbiota, by an increase in <italic>Bifidobacterium</italic> abundance (<italic>p</italic> = 0.083) and a decrease in <italic>Salmonella</italic> counts (<italic>p</italic> = 0.081). The higher energy level increased (<italic>p </italic>< 0.05) final body weight, average daily gain, and feed efficiency. The dietary inclusion of EM tended to increase final body weight (<italic>p</italic> = 0.081) and average daily gain (<italic>p </italic>= 0.082). The supplementation of EM increased (<italic>p </italic>< 0.05) the dry matter, gross energy, and ether extract digestibility in phase 1, and enhanced (<italic>p </italic>< 0.05) dry matter, gross energy, organic matter, and ether extract digestibility in phase 2. The fecal <italic>Escherichia coli</italic> population tended to be lower while <italic>Lactobacillus</italic> increased (<italic>p</italic> = 0.084) in the EM-supplemented group (<italic>p </italic>= 0.074). In conclusion, adding EM to the diet of grower pigs improved growth performance, nutrient digestibility, and may help regulating pathogenic bacterial populations.