Evaluation of the effects of black soldier fly larval hydrolysate on layer chicks

This study investigated the effects of dietary supplementation with black soldier fly larval hydrolysate (BSFH), an un-defatted crude hydrolysate, on the growth performance, immune organ indices, serum biochemical parameters, antioxidant status, intestinal morphology, and cecal microbiota of layer chicks. A total of 360 one-day-old Gushi layer chicks were randomly allocated to four treatment groups: a control group fed a corn-soybean meal basal diet and three experimental groups (E3, E6, and E9) supplemented with 0.3%, 0.6%, and 0.9% BSFH, respectively. The experimental period lasted for 63 days. Results indicated that BSFH supplementation dose-dependently improved average daily gain and feed-to-gain ratio. Average daily gain was significantly increased at the 0.6% and 0.9% levels, whereas feed-to-gain ratio was significantly improved only at the 0.9% level, with the 0.3% and 0.6% levels showing numerical trends; average daily feed intake was not significantly affected. BSFH supplementation did not significantly affect spleen or Fabricius bursa indices. At the serum biochemical level, BSFH at 0.3% and 0.6% significantly reduced alanine aminotransferase activity, while uric acid levels were dose-dependently decreased, with significant reductions observed at 0.6% and 0.9% supplementation levels; serum albumin was significantly increased at the 0.3% and 0.6% levels, and high-density lipoprotein cholesterol showed a linear increasing trend with supplementation level. BSFH also enhanced antioxidant enzyme activities, with serum glutathione peroxidase and catalase peaking at the 0.3% level, serum total superoxide dismutase peaking at the 0.6% level, and hepatic catalase being highest at the 0.6% level. Intestinal morphology analysis revealed that BSFH reduced jejunal crypt depth and increased the villus height to crypt depth ratio, with these effects observed specifically in the jejunum, while no significant changes were detected in the duodenum or ileum. Cecal microbiota analysis indicated that BSFH did not significantly alter overall microbial diversity but enriched the genus Fusobacterium in the cecum, with the highest relative abundance observed at the 0.6% supplementation level; species-level sequencing is warranted to clarify the functional implications of this shift. These findings suggest that BSFH is a promising and sustainable protein source for poultry feed, capable of promoting growth and potentially improving the overall health status of layer chicks.