Nutritional value of two different insects meal (Tenebrio molitor and Hermetia illucens) for broiler chickens: apparent ileal amino acid digestibility and apparent metabolizable energy

The aim of this study was to determine the apparent metabolizable energy (AME) and the apparent ileal amino acid digestibility coefficients (AIDC) of two insect meals (Tenebrio molitor and Hermetia illucens) in broiler chickens. Day-old male broiler chickens (Ross 708) were raised in floor pen till the age of 19 d. On day 19, ninety birds (3 each cage/10 replicates) of uniform body weight were selected and kept in thirty 2-floor cages. On d 26, birds were randomly allotted to the three experimental diets. A basal diet (BD) was administered for the adaptation period lasting 5 d. Two assay diets were developed by substituting 25% of the basal diet with Tenebrio molitor meal (TM) or Hermetia illucens meal (HI). For each diet, in order to calculate digestibility of amino acids (AA), celite was added. Digestibility was evaluated by the total collection of feces method from 31 to 34 d. AME was calculated using the following formula: AME insect meal (%; MJ/kg) = [AME of insect meal diet - (AME basal diet × 0.75)] / 0.25 Correction for zero nitrogen (N) retention was made using a factor of 36.54 kJ per gram N retained in the body in order to estimate the N-corrected apparent metabolizable energy (AMEn) (Hill and Anderson, 1958). N retention was calculated using the following formula: N retention = [(feed intake × N diet) - (excreta output × N excreta)]/ feed intake (kg) On day 35, all birds were euthanized to sample the content of the lower half of the ileum to perform the apparent ileal amino acid digestibility. Data were analyzed using Student's t-test for independent samples, with cage as the experimental unit. Differences were considered to be significant at P<0.05. No statistical differences between TM and HI were observed for AME and AMEn. The AME and AMEn values of TM and HI meal resulted 16.86 and 17.38 MJ/kg DM and 16.02 and 16.60 MJ/kg DM, respectively. The average AIDC of the 17 AA studied was higher (P<0.001) in TM than in HI, because the AIDC of isoleucine (0.822 vs. 0.446), lysine (0.852 vs. 0.463), methionine (0.804 vs. 0.424), phenylalanine (0.912 vs. 0.630), valine (0.819 v 0.622), alanine (0.928 vs. 0.861), aspartic acid (0.892 vs. 0.615), glycine (0.888 vs. 0.666), glutamic acid (0.855 vs. 0.741) and tyrosine (0.832 vs. 0.427) was higher (P<0.05) in TM than in HI. Overall, the present results showed that TM and HI meals are an excellent source of AME. TM is a good source of digestible AA, while HI is a moderate one.