Crickets on brewer’s spent grain diet stay stable, research shows

Farmed crickets reared on a high-inclusion diet of brewer’s spent grain achieved a steady five-generation production cycle despite being 19% smaller at adulthood than control groups, according to research published on pmc.ncbi.nlm.nih.gov. While the reduced body mass decreased overall harvest yield, the insects maintained high survival rates and stable reproductive output across all generations. The mass of the insects was obtained using an analytical balance from Mettler Toledo located in Columbus, United States, specifically model AB135-S. Body size was measured by capturing an image of each cricket through a ZEISS microscope, model Stemi 508 from Oberkochen, Germany, equipped with an Axiocam 208 color camera and ZEN Lite software from the same manufacturer.

Brewer Waste Replaces Grain in Five-Generation Trial

The study tracked Gryllodes sigillatus crickets raised on experimental diets containing up to 75% brewer’s spent grain, an organic waste product generated by the brewing industry at a rate of over 36.4 million tonnes worldwide each year. Before formulation into the rations, the spent grain was dried in a drying oven manufactured by Precision Scientific Co in Chicago, United States, model 31574, at 30 °C for approximately 10 days.

Researchers supplied the spent grain ingredient through two distinct feeding strategies over the five-generation span. One group received a constant 75% high-inclusion diet, while another experienced a gradual inclusion approach where spent grain increased incrementally from 15% to 75% across the generations.

Low-Inclusion Diets Boost Yield While High Inclusion Cuts Costs

Previous industry data shows that replacing 30% of soy with spent grain reduces feed costs by 29% per kilogram.

The findings indicate that spent grain contains adequate nutrition to support long-term commercial cricket production without cumulative generational declines from malnutrition or epigenetic factors. However, producers must weigh the economic savings of waste-based ingredients against the drop in individual cricket mass and total harvest yield when utilizing high-inclusion rations.