Responses of house crickets (Orthoptera: Gryllidae) to various dietary gross energy levels: effects on growth performance and nutrient deposition

Crickets present a sustainable protein alternative with a lower ecological footprint compared to traditional animal proteins. This research aimed to investigate the effect of dietary energy density on feed intake, growth, and body composition in house crickets (Acheta domesticus L., Orthoptera: Gryllidae) up to 45 d after hatching. The study consisted of 2 phases (7 to 20 and 21 to 45 d of age), with house crickets randomly assigned to 5 dietary treatments, each with six replicates. Dietary energy levels ranged from 3,819 to 4,265 kcal gross energy (GE)/kg in phase 1 and from 3,978 to 4,405 kcal GE/kg in phase 2. As dietary energy density increased, feed intake linearly decreased, while body mass linearly increased. In phase 1, protein retention increased from 72.1% to 85.5% as GE increased from 3,819 to 4,265 kcal /kg. Similarly, in phase 2, protein retention increased from 53.3% to 59.3% as GE increased from 3,978 to 4,379 kcal/kg. Correspondingly, the feed conversion ratio (FCR) improved with increasing dietary GE values. Broken-line analysis revealed the lowest FCR at 4,158 and 4,382 kcal GE/kg feed for house crickets from 7 to 20 and 21 to 45 d after hatching, respectively. These findings confirm the relevance of energy density in achieving optimal growth performance and provide valuable insights for formulating nutritious cricket diets. However, caution is warranted when extrapolating these results, as diets were formulated using GE instead of metabolizable energy (ME). Future studies should determine cricket-specific ME values to fine-tune dietary energy density.