Abstract: The test was designed for 4 treatments: wheat basal diet (control) and added with different levels of the xylanase (0.05%, 0.10% and 0.15%). Each treatment was divided into 5 replicates and each replicate included 40 male Tilapia nilotica. The initial weight of experimental fishes was (106.16±16.77) g. After they were fed in floating cages for 75 days, the growth index, vixcus index, hepatopancreas index, intestine index, apparent digestibility and muscle composition of them were measured, respectively. The results indicated that the xylanase significantly promoted the growth of Tilapia nilotica, The weight gain rate of control was 258.24%. The weight gain rate in 0.05% and 0.10% xylanase groupswas 8.25% and 17.45% higher than that of the control (P<0.01), respectively. The xylanase could eliminate the compensatory hyperplasy of digestive organs of Tilapia nilotica. Intestine index and hepatopancreas index of the control were 1.90 and 2.82, respectively, but were much lower in the xylanase groups. The xylanase could improve the digestion and absorption. Apparent digestibilities of dry matter and total carbohydrate of the control were 67.35% and 61.48% respectively. The digestive rates of dry matter for 0.05%, 0.10% and 0.15% xylanase groups were increased by 7.69%, 11.00% and 2.87% respectively. Apparent digestibility of total carbohydrate in the three groups were significantly higher than that of the control (P<0.01). The contents of crude protein in 0.05% and 0.10% xylanase groups were higher significantly than that of the control. The contents of crude fat of 0.05% and 0.10% xylanase groups were increased by 14.43% and 33.89%, respectively. The contents of crude ash in 0.05%, 0.10% and 0.15% xylanase groups were increased by 4.11%, 7.54% and 2.77%, while the contents of total calcium by 19.70%, 15.76% and 15.15%, and the contents of total phosphorus by 4.78%, 3.83% and 3.83%, respectively. The contents of moisture in 0.05% and 0.10% xylanase groups were lower significantly than that of the control (P<0.01). So we concluded that adding xylanase to wheat basal diet could promote Tilapia nilotica growth performance, the appropriate level is 0.10%.

Key words: Xylanase, Tilapia nilotica, Wheat basal diet, Growth performance

CLC Number: 

• S963