Lowering Chitin Content of Cricket (Gryllus assimilis) Through Exoskeleton Removal and Chemical Extraction and its Utilization as a Ruminant Feed in vitro.

Abstract

Cricket contains high crude protein level but it also contains considerable amount of chitin that may impede nutrient digestion and decrease production performance of animal. This experiment aimed to decrease chitin content of cricket (C) through exoskeleton removal (CER) or by chemical extraction (CCE). Nutritional evaluation of cricket was performed in two experiments. In experiment 1, three forms of cricket were prepared, i.e., C, CER and CCE. These were subjected to chemical composition determination and in vitro rumen fermentation incubation as individual substrates. In experiment 2, C and CER were included in concentrate rations at different proportions to substitute soybean meal (SBM), i.e., R1 (concentrate containing 30% SBM), R2 (50% SBM was substituted by C), R3 (100% SBM was replaced by C) and R4 (100% SBM was replaced by CER). The concentrates were then evaluated in vitro for their rumen fermentation and digestibility characteristics. Data were analyzed with analysis of variance and Duncan's test. Cricket was high in crude protein(CP), ether extract (EE) and chitin contents. Removal of exoskeleton decreased CP and chitin contents of cricket. Chemical extraction of cricket increased its CP and completely removed its chitin. Main fatty acids observed in cricket were linoleic acid, palmitic acid, oleic acid and stearic acid and the composition was unaltered due to exoskeleton removal or chemical extraction. Cricket was relatively highly digestible and exoskeleton removal and chemical extraction did not further improve in vitro dry matter digestibility (IVDMD) and in vitro organic matter digestibility (IVOMD) of cricket. The R1 and R2 revealed similar IVDMD and IVOMD, but R3 and R4 resulted in lower values for both parameters than those of R1 and R2 (p<0.05). Exoskeleton removal or chemical extraction effectively reduced chitin content of cricket and the insect may be used to substitute SBM up to 50% in concentrate for ruminant.