Cricket powder as an alternative protein source for broilers based onin vitro digestibility

Abstract

Pathogen contamination in fishmeal (FM) and the imbalanced amino acid profile in soya meal (SYM) are the disadvantages of the common protein sources in broiler diets. Therefore, FM, SYM and three species of cricket powder (Acheta domesticus: AD,Gryllus testaceus: GT andGryllus bimaculatus: GB) were screened based on thein vitro digestibility of dry matter (DMd), organic matter (OMd) and crude protein (CPd) to assess whether these insects could be a sustainable alternative protein source for broiler nutrition. Stomach mucosa, duodenal mucosa and pancreas were extracted from broilers to obtain crude enzyme extract (CTX) using two stages ofin vitro digestibility. The first stage was performed using gastric mucosa CTX, whereas CTX from the duodenal mucosa and pancreas were added for the second stage. SYM and GB had similar DMd, which were lower than FM, AD and GT (P<0.01). The highest OMd was observed in FM, followed by AD, GT, GB and SYM (P<0.01). A higher CPd was found in the crude protein calibration group (CPd-Cal), in which substrates were adjusted to obtain an equivalent crude protein level as the non-calibration group (CPd-Non). Interestingly, a strong correlation (r=0.99,P<0.01) was found between CPd-Cal and CPd-Non, with the highest CPd presented in FM, followed by SYM, AD, GB and GT (P<0.01). A significant negative correlation was found between the CPd from both groups (CPd-Cal and CPd-Non) and crude fibre (r=-0.96 and -0.95,P<0.05, respectively), whereas a positive correlation was observed for ash (r=0.91 and 0.93,P<0.05, respectively). AD has great potential as a protein source for broilers, greater than other cricket species, based on its DMd, OMd and CPd. However, the CPd of all insect species was lower than that of FM and SYM. Therefore, pre-treatment protocols should be performed to improve nutrient utilisation.