Effect of black soldier fly (Hermetia illucens) larvae oil feed inclusion on growth performance and fecal microbiome development in post-weaning pigs

• BSFL oil can replace conventional vegetable oils in piglet diets without negative effects on growth performance. • The natural, age-driven development of the fecal microbiome was not disrupted by the inclusion of BSFL oil. • Our findings validate BSFL oil as a safe and sustainable alternative feed ingredient for practical swine production. Post-weaning (PW) is a stressful period in the early life of growing pigs. Changes in diet may cause a shift in microbiome composition of the gastrointestinal tract (GIT), with potential effects on piglet health. Here, we evaluate the effect of black soldier fly larvae (BSFL) oil, as a sustainable nutrient source, on growth performance and fecal microbiome composition in PW pigs. Two trials were conducted, with Trial 1 including 60 piglets,of which 40 were sampled for microbiome analysis, and Trial 2 involving 160 piglets, of which 122 were sampled. All piglets were approximately 21 days old, Topigs/Pietrain crossbreed, weighed over 5 kg, and both trials lasted 39 days post-weaning. To assess the impact of BSFL oil blend on microbiome composition, 16S rRNA gene amplicon sequencing was performed on fecal samples collected on day 11 and 26 in Trial 1, and day 11 and 42 in Trial 2. No direct effects of BSFL oil blend implementation were observed on pig general performance in terms of body weight (BW), average daily gain (ADG) and gain-to-feed ratio (G). Moreover, no difference in microbiome development was observed with BSFL oil blend relative to soy and palm kernel oil. These results indicate that BSFL oil is a valid alternative nutrient source for weaned pigs, as both performance and microbiome are unaffected.