Brewery waste as a sustainable protein source for the banded cricket (Gryllodes sigillatus)

Crickets, like other edible insects, can convert organic by-products of the food and agricultural industries into high-value protein. Waste products high in protein like brewer’s spent grain and brewer’s spent yeast are particularly attractive replacements for unsustainable protein sources in cricket feed like fishmeal or soy. Such replacement will only be advantageous, however, if feeding on these waste products does not impact, or only minimally impacts, cricket survival, growth, and body composition. In this study, a farmed cricket species, Gryllodes sigillatus, was reared in isolation on experimental diets in which fishmeal was wholly or partially replaced with either brewer’s spent grain or brewer’s spent yeast. Cricket survival, development and macromolecular composition were not different across diets. However, wholly replacing fishmeal with brewer’s spent yeast or brewer’s spent grain reduced cricket adult body mass by approximately 16%. To extend these findings toward a farm environment, a second cohort of crickets were reared communally on diets in which fishmeal, and fishmeal and soy (a secondary protein source), were replaced by brewer’s spent grain. We found that in a communal environment, crickets reared on both diets performed equally as well as the control. Therefore, brewing waste products are promising candidates for use as a primary protein source in the feed of G. sigillatus. In addition to contributing towards the goals of a circular bioeconomy through the repurposing of waste, the use of brewing waste in cricket feed may have a positive impact of the cricket farming industry as a cost-effective and sustainable alternative to traditional feed.