Tenebrio molitor Larvae Meal Affects the Cecal Microbiota of Growing Pigs

The hypothesis tested was that dietary inclusion of insect meal (IM) causes an alteration in the cecal microbiota composition and its fermentation activity of growing pigs. Five-week-old male crossbred pigs were randomly assigned to three groups of 10 pigs each, and fed isonitrogenous diets either without (CON) or with 5% IM (IM5) or 10% IM (IM10) from Tenebrio molitor larvae for four weeks. The relative abundance of the phylum Bacteroidetes was lower in group IM10 than in group CON (p < 0.05), whereas the relative abundance of Firmicutes and the Firmicutes:Bacteroidetes-ratio tended to be higher in groups IM10 and IM5 than in group CON (p < 0.1). The relative abundance of the Proteobacteria tended to be higher in group IM10 than in groups CON and IM5 (p < 0.1). The concentrations of the total short-chain fatty acids in the cecal digesta did not differ between the three groups, but the concentrations of the branched-chain fatty acids in the cecal digesta were higher in group IM5 and IM10 than in group CON (p < 0.05). The present study shows for the first time that the replacement of soybean meal by Tenebrio molitor larvae meal causes a shift of the cecal microbial community and its fermentation activity in growing pigs.