Determining the protein formulation quality of pet food with hide beetles, Dermestes maculatus (Coleoptera: Dermestidae) utilizing different protein sources

Current pet food ingredient studies assess general macronutrient bioavailability using vertebrate models such as rats or chicks as companion animal alternatives. Vertebrates for such studies require approval and regulations from the Institutional Animal Care and Use Committee (IACUC) as stated in the US Animal Welfare Act. Currently, the only invertebrates evaluated under IACUC are cephalopods; hence, insects may be model candidates of interest without restrictions. We hypothesized that hide beetles, Dermestes maculatus, may be useful to evaluate protein quality because they are common pests of protein rich stored products, including pet foods. Hide beetles can efficiently transform energy from food sources at measurable growth rates and do well on high protein diets. Thirty second instar beetle larvae were placed on diets with different protein sources to test their growth. The diets included a positive control (a commercially available complete protein composition), spray-dried egg, soy protein isolate, corn gluten meal, fish meal, pea protein concentrate, or no protein (negative control). The larval weights were analyzed to evaluate protein efficiency ratio (PER), reflecting their protein conversion efficiency. Results showed that animal-based protein sources were of higher quality than plant-based protein sources. However, most of the diets were not commercial diets which are sprayed with lipids, allowing hygroscopicity absorption of water within the incubators. This study suggests that weight gain of hide beetle larvae generate a reliable PER value based upon the protein sources in their diets. Therefore, hide beetle PERs for evaluating pet foods could serve as alternatives to using vertebrate models.