Replacement of soybean oil with cold-extracted fat from Hermetia illucens in young turkey diets: Effects on performance, nutrient digestibility, selected organ measurements, meat and liver tissue traits, intestinal microbiota modulation, and physiological and immunological status

This study aimed to evaluate the partial or total replacement of soybean oil with cold-extracted Hermetia illucens larvae (BSFL) fat in young turkey diets on growth performance, coefficients of apparent ileal nutrient digestibility, pancreatic enzyme activities, selected gastrointestinal tract (GIT) segment measurements, microbial community modulation, selected biochemical blood indices, hormone concentrations, immune status traits, and muscle and liver tissue traits. A total of 216 7-day-old female turkeys (B.U.T. 6) were randomly allotted to 3 dietary treatments. Each group contained 6 replicate pens with 12 birds per pen. The birds were fed a soybean-maize basal diet enriched with 50 g/kg dietary fat, i.e., soybean oil (SO) in the control group, 50:50 SO and H. illucens larvae fat in the BSFL50 treatment group, and BSFL fat as the sole energy source in the BSFL100 group. The experiment lasted 28 days. The provided BSFL fat was characterized by high lauric and palmitic acid contents, as well as saturated fatty acids (SFAs), while concentrations of mono- and polyunsaturated fatty acids were higher in the SO group. The growth performance parameters were not affected (P > 0.05) by BSFL fat substitution. However, the apparent ileal digestibility of the ether extract was significantly increased (P < 0.001) after BSFL fat inclusion as the sole energy source with simultaneous enhancement (P < 0.001) of lipase activity. Partial or total replacement of SO with BSFL fat improved cecal microbiota communities by limiting (P < 0.001) Bacteroides-Prevotella cluster counts. Additionally, the beneficial effect of BSFL100 was observed in the case of a decreased (P = 0.004) IL-6 concentration. In conclusion, it is possible to partially or totally substitute SO in turkey diets with cold-extracted BSFL fat without any negative effect on growth performance, nutrient digestibility, physiological traits, or immunological status traits. Furthermore, the cold-pressing technique can be adopted and recommended to obtain BSFL fat as a dietary energy source in turkey nutrition.