Microbiota modulation by the inclusion of Tenebrio molitor larvae as alternative to fermented soy protein concentrate in growing pigs diet

Tenebrio molitor meal represents a promising protein source for animal nutrition due to its low environmental impact and high nutritional value. To date, there is limited data in the literature regarding the effects of Tenebrio molitor meal on the modulation of gut microbiota in growing animals, with most results focusing on poultry rather than pigs. The aim of this study was to evaluate the effects of replacing fermented soy protein concentrate with Tenebrio molitor meal on gut microbiota and feed digestibility in growing pigs. A total of 14 growing pigs (80 ± 2 days old) were randomly allotted to two groups: the control group (CON) was fed a commercial diet containing 4% fermented soy protein concentrate (48% crude protein), and the treatment group (TM) was fed a basal diet containing 5% of T. molitor larvae meal formulated to be isonitrogenous and isoenergetic. The study lasted 28 days. Animals were weekly weighted and feed refuse was routinely measured. Fecal, blood samples, and rectal swabs were collected for analysis. No differences were observed in growth and diet digestibility for the protein and lipid components throughout the trial. No differences in the serum concentrations of albumin, globulin, urea, and interleukin-6 were registered in both groups, suggesting an unaltered health status. The TM group showed a significant difference in the beta diversity index considering the total duration of the trial (treatment effect evaluated with PERMANOVA, R2 0.0771, p value = 0.0099) showing an increased abundance of Elusimicrobium spp. and a decrease in Asteroplasma spp. in TM compared to the CON group (p < 0.05). Obtained findings indicate that 5% T. molitor meal can be included as a partial replacement for soy in growing pig formula without impairing pig growth and gut microbiota composition.