Effects of replacing soybean oil with selected insect fats on broilers

The aim of this study was to investigate how oil obtained via super-critical CO2 extraction from Tenebrio molitor (TM) and Zophobas morio (ZM) larvae affect the growth performance, nutrient digestibility, lipid fatty acid composition of liver and breast tissue, and the expression of selected genes in the liver of broiler chickens. Two independent experiments were conducted on 72 and 108 one-day-old female Ross 308 chicks, respectively. Birds were fed soybean-maize diets developed by replacing 50 g/kg of the basal diet with various fats i.e., soybean oil (SO) and TM (Exp. 1), or SO, TM, and ZM (Exp. 2). In both trials, birds were kept in metabolic cages over a 28 day period. The fatty acid profile of used energy sources was determined. Both insect oils had higher monounsaturated fatty acids (MUFA) and lower polyunsaturated fatty acids (PUFA) concentrations comparing to SO. The addition of TM and ZM oil to the basal diet showed similar or better growth performance results compared to the SO diet over the entire experimental period. Insects’ oils addition increased nitrogen retention and the apparent digestibility of the ether extract in the total tract at days 7, 14, and 21 during TM administration. Similar effects on the apparent ileal digestibility of crude protein and ether extract or on AMEN were recorded among all groups in the second trial. The usage of selected insect oils significantly affected the fatty acid compositions of liver and breast tissue. Only TM addition had a positive effect on the PUFA (P = 0.004), MUFA (P < 0.001), UFA (P = 0.016), and SFA (P = 0.016) of breast muscle. Simultaneously, the TM treatment lowered the thrombogenic (P = 0.011) and atherogenic (P = 0.001) indices in the breast. The positive influence of insect oils addition to the basal diet on selected gene (HNF4a; APOA1; GIMAP5) expression in the liver was observed. Overall, these results highlight the possibility of completely replacing SO with TM and ZM oils in broiler diets without adverse influences on growth performance and nutrient digestibility. Moreover, the results of the present study suggest that TM oil positively affect meat quality which is a key factor for the modern consumer. It should be emphasized that both insect oils used in the study may be considered as a biologically active compounds modify molecular pattern at the mRNA level.