Benefits and risks of insect protein in largemouth bass diets
The research highlighted the effects of different inclusion levels of full-fat black soldier fly (BSF) meal on fish growth, gut health, and microbiota.
Studies have shown that H. illucens meal can effectively replace fishmeal in the diets of various fish species, including carp, salmon, and sea bass, without compromising growth or health when used appropriately. However, nutrient content varies depending on the larvae's diet, and the effects on gut health and physiological parameters require further research, noted the authors.
The largemouth bass (Micropterus salmoides) plays a vital role in China’s aquaculture industry, with annual production surpassing 600,000 tons (Peng et al., 2021). As a carnivorous species, its commercial farming relies heavily on diets high in animal protein.
Promising growth benefits
When included at a level of 16.78% in fish diets, BSF meal supported significant growth improvements in largemouth bass, making it a viable partial substitute for traditional fishmeal. However, researchers found a tipping point beyond which the benefits diminished.
Too much of a good thing
At higher inclusion levels, specifically 25.06% or more, the dietary use of BSF meal began to hinder fish growth and harm gut health. The study reported damage to the intestinal barrier, increased markers of inflammation, and disruptions to gut microbiota balance.
The inclusion of BSF meal influenced the intestinal environment in several ways:
- Gut morphology: Excessive levels led to shorter intestinal villi, increased villi width, and higher goblet cell numbers, which can compromise nutrient absorption.
- Inflammation: Higher doses triggered increased levels of pro-inflammatory markers and decreased protective anti-inflammatory signals.
- Gut microbiota: The addition of BSF meal altered the balance of gut bacteria, increasing beneficial Lactobacillus and Streptococcus at moderate levels but reducing Cetobacterium at higher levels.
In conclusion, the researchers observed that largemouth bass fed diets with 16.78% H. illucens meal exhibited enhanced growth performance, along with improvements in intestinal structure, barrier function, and immune capacity throughout the study. These findings, they continued, provide valuable preclinical evidence supporting the effectiveness of H. illucens meal in promoting fish health and shed light on its potential mechanisms of action.
Source: Animal Feed Science and Technology
Title: The effect of dietary full-fat Hermetia illucens larvae meal on growth performance and intestine physiology in largemouth bass (Micropterus salmoides)
Authors: W Dong et al
