Tenebrio molitor Larvae Meal Affects the Cecal Microbiota of Growing Pigs

SIMPLE SUMMARY: Insect meal obtained from the mass-rearing of edible insects is increasingly considered as a potential alternative protein source in farm animal feeding, which can be produced with lower environmental impact than conventional protein sources, such as soybean meal—the currently main dietary protein source for monogastric farm animals. Apart from the necessity to overcome existing legal obstacles regarding the use of insect meal as feed for farm animals, a further prerequisite for the inclusion of insect meal in feeding rations for monogastric farm animals is that animals’ health is not impaired. Whether feeding insect meal to growing pigs alters gut microbiota composition, which is vital to both health and performance is currently unknown. The present study in growing pigs shows that dietary insect meal causes a characteristic shift in the cecal microbiota composition. ABSTRACT: 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.