Abstract: To assess the feasibility of rearing Protaetia brevitarsis larvae on common agricultural wastes and their potential to convert low-value agricultural residues into high-quality protein products, we conducted an experiment with four typical agricultural wastes (rice straw, corn straw, sorghum straw, and shiitake mushroom spent substrate) as well as five composite substrates: 70% rice straw + 30% sheep manure, 70% corn straw + 30% sheep manure, 70% sorghum straw + 30% sheep manure, 70% shiitake mushroom spent substrate + 30% sheep manure, and pure sheep manure (served as a control). The impacts of different straw-based substrates on larval growth performance, feed conversion efficiency, and body nutritional composition of P. brevitarsis were investigated. The results showed that the second-instar P. brevitarsis larvae achieved the highest feed conversion efficiency on the 70% corn straw + 30% sheep manure substrate, whereas the third-instar larvae exhibited the highest conversion efficiency when fed with 70% sorghum straw + 30% sheep manure. There was no significant difference in crude protein content among larvae reared on different substrate treatments. The larvae fed the 70% corn straw + 30% sheep manure substrate had the highest contents of total amino acids and crude fat, which were significantly higher than those in the other treatment groups (P<0.05). In summary, P. brevitarsis larvae possess efficient conversion capabilities for the composite substrates of corn straw/sorghum straw and sheep manure. 70% corn straw + 30% sheep manure can be used as the rearing substrate to produce larvae with superior nutritional value. This study provides a novel approach for the resource utilization of agricultural wastes and contributes to promoting the development of the P. brevitarsis breeding industry, with significant theoretical and practical significance.

Key words: Protaetia brevitarsis, biotransformation, agricultural waste, straw, sheep dung, conversion efficiency