Crickets are not a free lunch: protein capture from scalable organic side-streams via high-density populations of Acheta domesticus

PLoS One. 2015 Apr 15;10(4):e0118785. doi: 10.1371/journal.pone.0118785. eCollection 2015.

Abstract

It has been suggested that the ecological impact of crickets as a source of dietary protein is less than conventional forms of livestock due to their comparatively efficient feed conversion and ability to consume organic side-streams. This study measured the biomass output and feed conversion ratios of house crickets (Acheta domesticus) reared on diets that varied in quality, ranging from grain-based to highly cellulosic diets. The measurements were made at a much greater population scale and density than any previously reported in the scientific literature. The biomass accumulation was strongly influenced by the quality of the diet (p<0.001), with the nitrogen (N) content, the ratio of N to acid detergent fiber (ADF) content, and the crude fat (CF) content (y=N/ADF+CF) explaining most of the variability between feed treatments (p = 0.02; R2 = 0.96). In addition, for populations of crickets that were able to survive to a harvestable size, the feed conversion ratios measured were higher (less efficient) than those reported from studies conducted at smaller scales and lower population densities. Compared to the industrial-scale production of chickens, crickets fed a poultry feed diet showed little improvement in protein conversion efficiency, a key metric in determining the ecological footprint of grain-based livestock protein. Crickets fed the solid filtrate from food waste processed at an industrial scale via enzymatic digestion were able to reach a harvestable size and achieve feed and protein efficiencies similar to that of chickens. However, crickets fed minimally-processed, municipal-scale food waste and diets composed largely of straw experienced >99% mortality without reaching a harvestable size. Therefore, the potential for A. domesticus to sustainably supplement the global protein supply, beyond what is currently produced via grain-fed chickens, will depend on capturing regionally scalable organic side-streams of relatively high-quality that are not currently being used for livestock production.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Feed*
  • Animal Nutritional Physiological Phenomena
  • Animals
  • Chickens / growth & development
  • Chickens / physiology*
  • Dietary Proteins*
  • Edible Grain
  • Gryllidae*
  • Poultry

Substances

  • Dietary Proteins

Grant support

Vestergaard Inc. provided partial support for this research by purchasing the materials used in the experiment. The remainder of the experiment was funded via a Jastro Fellowship through the Graduate Group in Horticulture and Agronomy and a Department of Plant Sciences Graduate Student Research Fellowship at the University of California Davis, Davis, California, USA (www.ucdavis.edu). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.