Effects of dietary carbohydrate sources on growth, overwintering and serum indexes in large-size Ctenopharyngodon idella

A 16-week feeding experiment was conducted to study the effects of different dietary carbohydrate sources (wheat, barley, corn, white sorghum, cassava) on growth, body composition, overwintering and serum indexes of large-size grass carp (Ctenopharyngodon idella) initial body weight (400.77±7.45) g. Every diet was randomly fed by triplicate cages, and each cage (2 m×2 m×2 m) was stocked with 30 fish. After the feeding trail, 15 fishes were kept in original cage for overwintering experiment in 16 weeks . Results show as follows: the weight gain rate (WGR) and protein efficiency ratio (PER) of grass carp in corn group was the lowest among experimental groups, and the feed coefficient ratio (FCR) was the highest, but other four groups had no significant difference; the condition factor (CF) in wheat group, was the highest, body weight (VSI) in corn group, and the hepatic body ratio (HSI) and intestine ratio (ISI) in cassava group were the highest, and these were highest among experimental groups; blood glucose (GLU) in wheat group and total cholesterol (T-CHO) in barley and white sorghum groups were the highest among other groups. The triglyceride (TG) content in the cassava group was significantly lower than that in the other groups. The crude fat of muscle in wheat, barley and corn groups was significantly higher than white sorghum and cassava groups. The crude protein content of muscle in cassava group was significantly lower among other four groups. Hepatic glycogen was significantly higher in the white sorghum and cassava groups than other groups. Muscle glycogen was significantly higher in the barley and white sorghum groups than other groups. After wintering, the weight loss of barley grass carp was significantly higher than that of other groups. The decrease rate of HSI was significantly lower than other groups. The hepatic glycogen content was significantly increased, and the decrease of GLU was significantly less than that of other groups. The crude muscle protein decreased most rapidly. There were no significant differences in weight loss after winter in other groups. The CF was the highest drop rate in wheat group, the HSI decline in corn and cassava groups was significantly greater than other groups. Corn group had the largest decrease in VSI. In conclusion, under the puffing process conditions, wheat, cassava, and white sorghum are suitable sugar to be sources to be added in feed for large-size grass carp, and cassava has the lowest weight-increasing costs with growth, weight gain cost, and overwintering as evaluation indicators.