Feeding value of black soldier fly larvae compared to soybean in methionine- and lysine-deficient laying hen diets

To increase the sustainability of egg production, alternatives to soybean in poultry nutrition are intensively searched for. Black soldier fly larvae (BSFL) could have a great potential, but the comparative protein value to soybean is not well known. The main objective of this study was to facilitate this comparison by using experimental diets clearly limited in calculated supply of sulphurous amino acids and lysine. Fifty laying hens (Lohmann Brown Classic), aged 40 weeks, were fed one of five diets for 7 weeks (n=10). Two diets were based on soybean cake and oil (SS, SS-) as protein and energy sources, and three diets contained partially defatted BSFL meal and fat from two different origins (AA-, AB-, BB-). Different from SS, all other diets were designed to be deficient in methionine and lysine in relation to requirements by >20%. The realised supply with total sulphurous amino acids and lysine was indeed superior with SS even though this diet was analysed to be more deficient in methionine than the BSFL-based diets. Despite the calculated deficiency in limiting amino acids, laying performance of the hens of all groups was similar and ranged between 93 and 97%. Similarly, egg mass, daily feed intake and feed efficiency were not influenced by the BSFL-based diets. The yolks of group BB- were more intensely coloured compared to the others indicating a difference between BSFL origins. Yolks of SS-, but not of the BSFL-based diets, had lower contents of dry matter and ether extract than those of SS. Including BSFL into the diet did not influence the odour of the eggs tested in scrambled form. The results show that soybean-based feeds for laying hens may be completely replaced by BSFL- based feeds and suggest that the recommendations for amino acid supply of laying hens might need revision.