Apparent digestibility of crude proteins and crude fats in 17 feed ingredients in grass carp

The grass carp collected from local farm were temporarily cultured for 2 weeks, experiment body weight 150～180 g and water temperature (23±1)℃. The diets consisted of 70% reference diet and 30% test ingredients including fish meal (import), soybean meal, corn gluten meal, brewers dried yeast, rapeseed meal, yellow rapeseed meal, black rapeseed meal, fish meal (domestic), meat meal, casing meal, expanded soybean, cottonseed meal, double-low rapeseed meal, crab meal, corn germ meal, sesame meal and distiller's grains meal, respectively. Using Cr 2O 3 as the indicator the results show that the apparent digestibility rates of dry materials of fish meal both import and domestic are over 80% in grass carp, while those of crab meal, meat meal and casing meal are less than 60%. For the proteins in fishmeal (import and domestic), crab meal and meat meal, the grass carps have the similar digestibility ranged from 79.21% to 87.54%, but for the proteins in casing meal the digestibility is low (69.89%). For the plant ingredients, the highest digestibility of dry material appears in expanded soybean which is 79.10% and follow the soybean meal, yellow rapeseed meal, sesame meal and rapeseed meal, et al., and the low digestibilities appear in cottonseed meal, corn germ meal and corn gluten meal. The grass carp has high digestibilities of protein in yellow rapeseed meal, double-low rapeseed meal, soybean meal and expanded soybean meal, all more than 85%, and the followings are rapeseed meal, black rapeseed meal, sesame meal, cottonseed meal and corn germ meal, nearly 80%. Meanwhile, the digestibility of monocell protein diet was also tested.