Effects Of Three Microecologicalagents On Growth Performance, Physiological Function And Intestinal Mucosa Of Grass Carp(Ctenopharyngodon Idellus)

The aim of this experiment was to investigate the effects of three microecologicalagents on growth performance, physiological function and intestinal mucosa of grass carp. The 624 grass carp with an average body weight of 69.51±6.29 g were randomly allocated into 13 groups with 3 replicates of 16 fish. The control group was fed with the basal diet, while trial groups were fed with the basal diet added with 200 mg/kg, 400 mg/kg, 800 mg/kg, 1200 mg/kg, 2000 mg/kg raffinose, 1000 mg/kg, 1500 mg/kg, 2000 mg/kg, 2500 mg/kg bacillus subtilis and 1000 mg/kg, 2000 mg/kg yeast culture respectively. The experiment lasted for 70 days.Test one was to investigate the effects of raffinose on growth performance, physiological function and intestinal mucosa of grass carp. The results showed that: compared with the control group, Specific growth rate (SGR) and feed conversion ratio (FCR) were improved by adding different quantities of raffinose, and the group of 1200 mg/kg was increased significantly (P<0.05). And the fat deposition rate (FDR) was also increased significantly(P<0.05), except the group of 400 mg/kg. Triglyceride (TG) was significantly improved (P<0.05), and high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C) were decreased significantly (P<0.05).The correlation coefficient of amylase and protease with raffinose were over 0.80. The density of microvill were improved significantly except for that of the group 2000 mg/kg (P<0.05). Compared with the flavomycin group, SGR, FCR and FDR were improved significantly (P<0.05). And the activity of amylase and protease were enhanced, the density of intestinal microvilli were improved significantly (P<0.05). In conclusion, raffinose can improve the growth performance by improving intestinal mucosa of grass carp, promoting vitality of intestinal amylase and protease, and regulating lipid metabolism, thus it can improve the growth performance.In the experimental conditions, it can replace flavomycin for the suitable range from 200 mg/kg to 1200 mg/kg.Test two was to investigate the effects of bacillus subtilis on growth performance, physiological function and intestinal mucosa of grass carp. The results showed that: compared with the control group, Specific growth rate (SGR) and feed conversion ratio (FCR) were improved by adding different quantities of bacillus subtilis, and the group of 2000 mg/kg was increased significantly(P<0.05). And the fat deposition rate (FDR) was also increased significantly (P<0.05), except the group of 2500 mg/kg. Triglyceride (TG) was significantly improved (P<0.05). The correlation coefficient of amylase and protease with raffinose were over 0.89. The width and density of microvill were improved significantly(P<0.05). Compared with the flavomycin group, SGR, FCR and FDR were improved significantly (P<0.05).And the activity of amylase and protease were enhanced, the density and width of intestinal microvilli were improved significantly (P<0.05). In conclusion, bacillus subtilis can improve the growth performance by improving intestinal mucosa of grass carp, promoting vitality of intestinal amylase and protease, and regulating lipid metabolism, thus it can improve the growth performance.In the experimental conditions, it can replace flavomycin for the suitable range from 1000 mg/kg to 2000 mg/kg.Test three was to investigate the effects of yeast culture on growth performance, physiological function and intestinal mucosa of grass carp. The results showed that: compared with the control group, Specific growth rate (SGR) and feed conversion ratio (FCR) were improved by adding different quantities of yeast culture, and the group of 1000 mg/kg was increased significantly (P<0.05), and the fat deposition rate (FDR) was also increased significantly (P<0.05). Triglyceride (TG) was significantly improved (P<0.05).The activity of amylase and protease were improved. The height of folding were improved significantly (P<0.05), and the height and density of microvill were improved. Compared with the flavomycin group, SGR, FCR and FDR were improved significantly (P<0.05). And the activity of amylase and protease were enhanced (P<0.05), the density and width of intestinal microvilli were improved significantly (P<0.05). In conclusion, yeast culture can improve the growth performance by improving intestinal mucosa of grass carp, promoting vitality of intestinal amylase and protease, and regulating lipid metabolism, thus it can improve the growth performance. In the experimental conditions, it can replace flavomycin for the optimal dosage was 1000 mg/kg. Summary: These results suggest that in appropriate circumstances, raffinose, bacillus subtilis and yeast culture can replace flavomycin to improve the intestinal mucosa morphology, and promote the growth performance of grass carp.