Dietary fishmeal replacement by black soldier fly larvae meals affected red drum (Sciaenops ocellatus) production performance and intestinal microbiota depending on what feed substrate the insect larvae were offered

Authors: YAMAMOTO, FERNANDO - Texas A&M University; SUEHS, BLAINE - Texas A&M University; ELLIS, MATTHEW - Texas A&M University; BOWLES, PAUL - Texas A&M University; OLDER, CAITLIN - Texas A&M University; Hume, Michael; BAKE, GABRIEL - Texas A&M University; TOMBERLIN, JEFFERY - Texas A&M University; GATLIN III, DELBERT - Texas A&M University

Submitted to: Animal Feed Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2021
Publication Date: 12/4/2021
Citation: Yamamoto, F.Y., Suehs, B.A., Ellis, M., Bowles, P.R., Older, C.E., Hume, M.E., Bake, G.G., Tomberlin, J.K., Gatlin Iii, D.M. 2021. Dietary fishmeal replacement by black soldier fly larvae meals affected red drum (Sciaenops ocellatus) production performance and intestinal microbiota depending on what feed substrate the insect larvae were offered. Animal Feed Science and Technology. 238. Article 115179. https://doi.org/10.1016/j.anifeedsci.2021.115179.
DOI: https://doi.org/10.1016/j.anifeedsci.2021.115179

Interpretive Summary: This study evaluated the growth of red drum fish given feed containing black soldier fly larvae meals (BSFLMs) as replacement for fishmeal protein and made from larvae reared on brewer's spent grains (BSFLM-B) or a commercial fly nutrient (BSFLM-C). The nutrient content of BSFLM-B was significantly better than that in BSFLM-C. Fish fed the BSFLM-B and BSFLM-C diets saw slightly less, but not significant, weight gain than fish fed the control diet. Compared to the control diet, the BSFLMs significantly changed the relative numbers and types of intestinal bacteria and have the potential to decrease populations of pathogenic bacteria. However, these changes had no significant effects on meat yield, liver weight, body cavity fat content, or fish survival. This work establishes that BSFLMs can partially replace fishmeal in red drum fish feed without significantly impairing growth and survival. Results of this study are of interest to fish farmers and researchers seeking to reduce the use of the more expensive and decreasing supply of fishmeal for feeding farmed fish.

Technical Abstract: This study, which evaluated production performance of red drum (Sciaenops ocellatus, L.), fed two black soldier fly larvae meals (BSFLMs), as 65% replacement for fishmeal protein, from larvae reared on brewer’s spent grains (BSFLM-B) or a commercially available substrate (BSFLM-C Flies reared on brewer’s spent grains had a higher (P=0.01) lipid, ash (P=0.02) and energy content (P=0.01), as well as higher methionine and cysteine (P=0.0004) concentrations, as compared to flies reared on commercial substrate. Groups of 12 fish were stocked in 15 (n=5), 38-L aquaria, and the three experimental diets were distributed in a completely randomized block design. Fish fed BSFL-B diets presented impaired, but not significant, weight gain and feed efficiency when compared to the control group. Red drum fed BSFL-C diets had growth performance numerically lower, but not statistically different than fish fed the control diet. Dietary treatments significantly affected the nutritional content of the red drum whole-body. The dietary inclusion of BSFLMs significantly impacted the intestinal microbiome in alpha and beta diversity, the relative abundances of bacteria, and the predicted functions of the bacterial metagenome using PICRUSt2. In conclusion, a partial replacement of fishmeal could be attained by BSFL-C without significantly impairing growth performance, and both BSFL meals altered the intestinal microbiome when compared to red drum fed a reference diet.