Nutrient digestibility of Hermetia illucens and Tenebrio molitor meal in broiler chickens

Poultry meat is a market increasing all over the world thanks to the absence of cultural or religious obstacles. One of the factors that most influence the costs of broiler production is the price of protein source. Invertebrates are a raw material included in the Feed Register Material of the EU and, for this reason, they could represent a material for feed manufacturing. In this regard many studies have already been performed, especially by teams from developing countries to find unconventional protein sources such as maggot [1], house fly pupae [2], silkworm [3] meal. Thirty 1-d-old male broiler chickens (Ross 708) were raised in floor pens until the age of 19 d and fed a diet formulated to meet their requirements. From the age of 19 d, birds were kept individually in 2-floor cages. At the age of 25 days a basal diet (BD) was administered for the adaptation period lasting 5 d. Two assay diets were developed by substituting 250 g/kg (w/w) of the basal diet with the Hermetia illucens (HD) or Tenebrio molitor (TD) meal. The apparent digestibility (AD) trial was performed using the total excreta collection method. Digestibility was evaluated from 31 to 34 d. Feeds and excreta were analyzed for dry matter, organic matter, total fat, crude protein [4], and gross energy (IKA C7000, Staufen, Germany). The nutrient digestibility data were analysed using the one-way analysis of variance, with cage as the experimental unit. Differences were considered to be significant at P<0.05 and significant differences between means were separated by the Tukey's least significant difference test. The AD of dry matter and organic matter showed the same trend and resulted higher for the basal diet than the two tested diets (P?0.001) (BD=69.2 and 71.5%; HD=64.3 and 68.2% and TD=64.6 and 67.2% respectively). The highest AD of total lipids was found in HD group (97.8%), the lowest in TD group (94.0%) and the intermediate value in BD (95.7%) (P<0.001). The AD of crude protein and energy showed the same trend and resulted highest in BD (76.9 and 77.1%), intermediate in HD (69.1 and 75.7%) and lowest in TD (66.1 and 74.3%). Results suggest that the two insect meal tested in the present study are suitable as alternative protein source in broiler chicken nutrition.