Evaluation of nutritional values of defatted black soldier fly (Hermetia illucens) larvae meal using the precision-fed cecectomized rooster assay

The use of insects, such as black soldier fly (Hermetia illucens) larvae meal (BSFLM), as an alternative protein source for pet food has gained attention due to their high nutritional value. The objective of this study was to determine the chemical composition, amino acid (AA) digestibility, and protein quality of defatted BSFLM of 2 distinct substrates (wheat and corn, BSFLM-W and BSFLM-C). Whole egg powder (WEP) and chicken meal (CM) were used as reference protein sources commonly used in pet foods. Twenty cecectomized roosters (5 per treatment) were randomly allocated to the test ingredients BSFLM-C, BSFLM-W, CM, and WEP. After 26 h of feed withdrawal, 20 g of each ingredient were tube-fed, and excreta were collected for 48 h. Digestible indispensable amino acid score (DIAAS)-like values were calculated based on the Association of American Feed Control Officials (AAFCO), The European Pet Food Industry Federation (FEDIAF), and National Research Council (NRC) reference values for different life stages of dogs and cats. CM had the highest crude protein concentration (70.2%), followed by BSFLM-C (65.6%), BSFLM-W (59.8%), and WEP (51.2%). In general, WEP had higher AA digestibility than BSFLM and CM. BSFLM-C had comparable arginine digestibility to WEP, outperforming BSFLM-W and CM. BSFLM-C showed high AA digestibility, surpassing 75% for all indispensable AAs, particularly exceeding CM. DIAAS-like values were calculated, revealing methionine + cysteine limitations for growing puppies and adult dogs in BSFLM-W, BSFLM-C, and CM according to AAFCO and FEDIAF. NRC identified methionine + cysteine as limiting for all sources in adult dogs. For growing kittens, methionine + cysteine and phenylalanine + tyrosine were limiting in BSFLM-W, BSFLM-C, and CM based on AAFCO and FEDIAF, while NRC and FEDIAF identified phenylalanine + tyrosine as limiting for WEP. For adult cats, phenylalanine + tyrosine was limiting in BSFLM-W, BSFLM-C, and CM according to AAFCO and FEDIAF, with NRC identifying it across all sources. In summary, BSFLM sources had high AA digestibility, comparable to traditional protein sources used in pet foods. When formulating diets for pets using BSFLM as the main protein source, methionine + cysteine and/or phenylalanine + tyrosine concentrations should be considered as they were the primary limiting AAs.