# The Impact of Energy and Protein Levels on Yellow Mealworm Growth and Chemical Composition

## TL;DR

This study shows that protein content in diets strongly affects yellow mealworm growth and fat levels, while energy levels have less impact.

## Contribution

The study identifies optimal dietary protein levels for maximizing insect protein yield and minimizing fat content.

## Key findings

- Larval weight gain was primarily influenced by dietary protein, not energy levels.
- Fat content in mealworms decreased significantly with higher dietary protein.
- Protein content in mealworms showed less variation and was highest with high-protein, high-energy diets.

## Abstract

In this study, we examined how different diets affect yellow mealworm larvae production. Nine diets with varying energy and protein levels were tested. Larval weight gain depended mainly on protein content, while energy level had no significant effect. Feed conversion efficiency was influenced by both energy and protein levels. Diets strongly affected insect composition, especially fat content, which decreased as dietary protein levels were increased. Protein content varied less than fat content, and was highest in insects fed high-protein, high-energy diets.

To maximize protein production from insects, it is essential to understand their nutritional requirements, production characteristics, and the chemical properties of the resulting feed, along with how these factors depend on the insects’ diets. This research involved the use of nine different insect diets, all based on wheat bran. Corn and soybean meal were included to enhance the energy and protein content. The weight gain of larvae was significantly affected by the level of protein in their feed; however, the energy level did not have a significant impact on the weight gain measured in grams per day per tray. This gain ranged from 0.57 g/day per tray for insects fed low-energy, low-protein diets to 0.71 g/day per tray for those fed high-protein, medium-energy diets. Feed conversion ranged from 1.83 to 2.34 and was significantly influenced by energy and protein levels. The chemical composition of reared insects showed significant differences, particularly in fat content. The fat content ranged from 38.5% with a low-protein diet to just 26.9% with a high-protein diet. In contrast to fat content, the variability in protein content was smaller, ranging from 44.8% in a low-protein, high-energy diet to 51.9% in a high-protein, high-energy diet.