Chitin utilisation by broilers and its effect on body composition and blood metabolites

1. Little is known about the ability of farmed poultry to digest chitin and derive nutrients from the ingestion of insects. 2. Commercial chitin derived from crustacean shell waste was found to contain 373 g crude protein, 265 g ash, 23.5 g ether extract, 130 g calcium and 16.4 g phosphorus per kg, on an air-dry basis. 3. It was included in diets at 0, 25, 50 and 75 g chitin per kg and fed to 320 1-d-old broiler males, over a 21-d period. There were no statistically significant treatment effects on weight gain or feed efficiency. Apparent digestibility of chitin protein was 0.48, 0.50 and 0.45, at the 25, 50 and 75 g per kg inclusions, respectively. Mean AME and AMEN values of chitin were determined as 8.97 and 8.86 MJ/kg. 4. In a subsequent study, mean TME and TMEN values of chitin were determined to be 8.23 and 8.21 MJ per kg, respectively. Addition of chitinase to the diet increased TME and TMEN of chitin to 8.81 and 8.79 MJ per kg, respectively (P < 0.05). True digestibility of chitin protein was determined to be 0.87. 5. Triglyceride concentrations in liver and breast meat were significantly reduced by chitin inclusion. No significant differences in carcase yield at 21 d of age were found. Serum cholesterol and triglycerol concentrations were reduced significantly by dietary chitin, the lowest levels being observed at the 50 g per kg inclusion level. 6. These findings indicate the ability of modern poultry to digest chitin but suggest that the ingestion of insects is not an important source of nutrients, at least from the exoskeleton.