Utilization of insects and seaweeds as alternative protein sources in companion animal diets: a review

The companion animal diet industry in Korea has grownrapidly, driven by the increasing recognition of pets as family members and rising interest in pet wellness. Although meat by-products, fish meals and soy protein are widely used as conventional protein sources in companion animal diets, they present several limitations, including nutritional imbalances, allergenicity, resource depletion and environmental burden. This review evaluates the potential of insects and seaweeds as alternative protein sources for companion animal diets. The crude protein (CP) content of basis black soldier fly larvae (BSFL) and mealworm stypically ranges from 40% to 60% on a dry matter (DM) and includes a balanced profile of essential amino acids such as lysine and methionine. Their nutritional value is comparable to that of conventional protein sources, making insects a viable option as a primary protein source for growing companion animals. The BSFL demonstrate excellent digestibility, in some cases exceeding chicken meal for essential amino acids. Additionally, insect production reduces environmental impact, generating substantially lower greenhouse gas emissions then livestock. However, potential concerns remain, including reduced digestibility due to high chitin content in some species and the risk of allergenicity due to cross-reactivity with crustaceans. Seaweeds generally contain 10% to 30% CP on a DM basis and provide various functional compounds, including polyunsaturated fatty acids, fucoidan, and alginate.These bioactive substances offer benefits in immune modulation, skin and coat health and weight management. Seaweeds also provide environmental advantages as they require no arable land and absorbing atmospheric carbon dioxide during cultivation. However, variations among species in nutritional composition and the potential for heavy metal accumulation require careful consideration. In conclusion, insect protein shows strong potential as a primary nutritional source, whereas seaweed protein serves effectively as a functional supplement. The combined use of these alternative ingredients provides a sustainable strategy to reduce reliance on meat-based proteins while supporting the overall health and well-being of companion animals.