Effects Of Different Dietary Carbohydrate Levels On Growth And Physiological Functions Of GIFT Strain Of Nile Tilapia(Oreochromis Niloticus)

The fishmeal, bean oil and gelatinized corn starch were used as protein, lipid and carbohydrate respectively. In this experiment, the feed added with carbohydrate(10%、15%、20%、25%、30%、35%、40%、45%) was used for breeding Tilapia.This experiment was conducted to determine on growth、body composition、serum biochemical indexes、digestive enzyme activities、 immunity、survival and serum biochemical indexes at low temperatures to further explore the physiological effects of tilapia carbohydrate utilization capacity and sugar.49days of feeding experiment, the following results have been:The effect of different carbohydrate on growth of Tilapia:Under the experimental conditions, feed carbohydrate level of35%(Group6), Tilapia fish grow the fastest, the specific growth rate (4.37±0.03) weight gain rate (13716.74±423.14), significantly higher than1、2、and3groups (P>0.05); feed conversion ratio (1.07±0.11) minimum, with1、2、3、4、6significant difference (P<0.05)The effect of different carbohydrate on fish nutrition composition of Tilapia: With the elevated levels of intake of feed carbohydrate, fish muscle glycogen, crude fat content gradually increased;fish glycogen content first increased and then decreased, the highest concentrations of6groups (8.17±4.21). The impact of feed carbohydrate levels on the Histological observe liver of Tilapia:feeding the low level of carbohydrate feed (Group1、Group2、Group3), liver tissue sections of a large number of hepatocyte vacuolation, nuclear migration the disappearance of the phenomenon and the cytoplasm;a high level of carbohydrate intake (Group7、Group8), and also seeing the same phenomenon;4、5、6Group liver tissue slices than normal.Effect of the different carbohydrate on Tilapia’s serum biochemical indexes:With the increased levels of fish intake of carbohydrates, various groups of fish serum alanine aminotransferase activity was declining; serum total protein concentration was increased by trends; four groups, the low serum concentration of total bile acid concentration, indicating that about30%compared to the other level of carbohydrate intake, intake of fish liver damage.Effect of the different carbohydrate on Tilapia’s Enzyme activity:With the levels of fish intake of carbohydrates, fish liver esterase, lipoprotein lipase, trypsin activity increases with dietary carbohydrate level first increased and then decreased liver esterase activity (244.90±2.13) and the most,2、3、4group, the activity of lipoprotein lipase activity; serum phosphofructokinase activity showed the tendency to increase as the carbohydrate level of fish intake increased.The effect of different carbohydrate on immunity of Tilapia:this experiment,fish total antioxidant capacity of the test activity increased with the level of dietary carbohydrate increased and then decreased to6、7group(7.88±0.52、7.65±5.81) with a difference significant(P<0.05); lysozyme activitysix groups(54.08±7.64) activity when the sugar level of fish intake further increased lysozyme activity decreased; fish total superoxide dismutase activity was rising with the elevated levels of fish intake of carbohydrate:5、6、7、8-group activity is relatively high, significantly higher than group1and2(P<0.05). Catalase activity in6groups(14.20±2.23) higher activity, was significantly higher than7、8group (P<0.05).Feed different carbohydrate levels on survival in tilapia at low temperatures:the water temperature at11℃, each group survival rate showed the first rise and then a downward trend; group survival rate of up to100%,7、8group lowest difference was significantly(P<0.05);10℃, the groups survival rate showed first increased and then a downward trend, the highest survival rate was100%;9℃,3、4、5、6groups have a small number of fish still survived, but no difference between the two groups.The effect of different carbohydrate Tilapia’s serum biochemical indexes at low temperatures:low temperatures, high levels of carbohydrates intake of fish, serum globulin fish liver injury, making the protein synthesis weakened, thereby globulin concentration first increased and then decreased; fish kidney and gill damage, lead to the filtration of creatinine or excretion function, and serum creatinine levels; weakened fish osmoregulation of the cell membrane function, the increase in membrane permeability, resulting in fish serum K+and Cl-concentration, and Na+concentration first decreased and then rose.In this experiment, the present results suggested that the optimal dietary carbohydrate level was30%-35%.