Quality of the protein from black soldier fly larvae compared to soybean protein in organic broilers

Summary

Insects in general and especially the larvae of the black soldier fly (BSF) are globally discussed as a possible replacement for soybean in animal nutrition. However, information about their feeding value is scarce. Therefore an experiment was carried out with organic broilers where soybean cake and oil (S) was replaced by defatted meal and fat of BSF larvae grown on two different substrates (A/B). 80 Hubbard S757 broilers were kept in pairs and fattened from day 15 to 63/64 of life with one of the five following diets: a positive control (S/S, protein meal/oil, 21% CP) complying with recommendations for this broiler type, a negative control (SS-, 18% CP), a diet with BSF meal A and fat A (AA, 17% CP), a diet with BSF meal A and BSF fat B (AB, 17% CP) or a diet with BSF meal B (BB, 17% CP, no extra fat). Diets SS-, AA, AB and BB theoretically induced a protein deficiency to determine whether the protein value of the insect material is comparable to that of soybean. One animal per pair was analysed for carcass and meat quality. The average daily gains (g) were 27.1, 20.4, 27.5, 26.4 and 19.9 for SS, SS-, AA, AB and BB (SSand BB, P<0.05 against the others). The corresponding feed efficiency (g feed/g gain) was 2.7, 3.2, 2.8, 2.9 and 3.1 (SS- and BB, P<0.05 against SS). Dressing percentage was similar at ~68% in all
groups. Breast meat proportion was greater (P<0.05) with SS (21%) compared to all other diets (all ~18%). Insect-based diet BB enhanced (P<0.05) the yellowness of skin and meat. Cooking loss differed (P<0.05) between SS (14.3%) and BB (17.2%), and shear force of the meat was also highest with BB. The results indicate that BSF protein meal A has a better protein value than soybean cake as it permitted a better growth than SS- despite the same protein content. Yet, diet AA could not prevent the impairment in breast meat proportion also observed in SS-. BSF protein meal B was widely equivalent to soybean cake. In conclusion, BSF protein meal is a high quality protein source, but its protein value varies between origins.