Research by Professor Haga Yutaka of Tokyo University of Marine Science and Technology, Professor Morioka Shinsuke of Human Environment University, Professor Shimoda Masami of the University of Tokyo, and Professor Sato Shuichi of Fukui Prefectural University has found that feeding farmed red sea bream feed containing dried powder of American soldier fly larvae (American soldier fly meal) diversifies the intestinal flora (intestinal bacterial flora) and increases the number of bacteria that produce functional substances.
With the world's population increasing, it is expected that insects, which have not been used until now, will be used as raw materials for farmed fish and livestock feed. In particular, American soldier fly meal, made from dried powder of American soldier fly larvae, is expected to be a useful alternative to fish meal, which is currently a protein source for animal feed.
In this study, we fed red sea bream juveniles diets in which American soldier fly meal was gradually added instead of fish meal, and examined the rearing performance, such as growth and feed efficiency. In addition, because previous studies have suggested that diets containing American soldier fly meal affect the intestinal microbiota, we performed metagenomic analysis of the taxonomic group composition, diversity index, and enzyme gene clusters involved in the production of functional substances in the intestinal microbiota of reared red sea bream.
A 45-day growth test was conducted on four diets: one containing 15% fishmeal, and the other containing 30%, 45%, and 4% of that fishmeal replaced with soldier fly meal. The results showed that replacing approximately 67% of the fishmeal with soldier fly meal (containing approximately 67% of the total fishmeal) did not have a significant effect on rearing performance. Furthermore, it was discovered that the intestinal flora of sea bream fed the soldier fly meal-containing diet was significantly more diverse than that of sea bream fed a conventional fishmeal-based diet, and that the bacterial groups that contribute to fish health and growth were significantly increased.
From the above, it has been shown that American soldier fly meal diversifies the intestinal flora of red sea bream and increases the number of microorganisms that produce functional substances, and this result can be said to be a discovery of new possibilities for insect feed. In the future, it is hoped that research into more effective compound feed will lead to the development of technologies to prevent disease, maintain the health, and improve breeding results of farmed fish, which are expected to see increased production.
