粪肠球菌对吉富罗非鱼的生长、体组成、消化酶活性及血液生理生化指标的影响

为研究饲料中添加不同浓度的粪肠球菌对吉富罗非鱼生长、体组成、消化能力及血液生理生化指标的影响,实验选用初始体质量为(50.59±0.59)g的吉富罗非鱼300尾,随机分成5组,每组设3个重复,每个重复20尾鱼,养殖实验期60 d。分别投喂实测含1.3×10~2(对照组)、1.4×10~5、1.7×10~6、1.5×10~7和1.8×10~8 CFU/g粪肠球菌的5种等氮(36%)等脂(6.75%)的实验饲料。结果显示:(1)罗非鱼的末均重(FBW)、增重率(WGR)、特定生长率(SGR)和尾均摄食量(FI)均在1.5×10~7 CFU/g组达到最大且显著高于对照组,而饲料系数(FCR)显著低于对照组。以FBW、WGR和SGR为评价指标,通过二次回归分析得出,罗非鱼饲料的粪肠球菌适宜添加浓度范围为7.5×10~7~1.1×10~8 CFU/g。(2)各添加组的全鱼粗蛋白含量均显著高于对照组,1.5×10~7 CFU/g组的粗脂肪含量显著高于对照组,各组间全鱼水分和粗灰分含量无显著差异。1.5×10~7 CFU/g组的干物质、蛋白质和脂肪沉积率均达到最大值且显著高于对照组。(3)1.5×10~7和1.8×10~8 CFU/g组的肠脂肪酶活性均显著高于对照组,而1.8×10~8 CFU/g组的肠道蛋白酶活性显著低于对照组;各组间肠道淀粉酶活性无显著差异。(4)1.5×10~7 CFU/g组的平均红细胞体积、血红蛋白浓度和血小板数均显著低于对照组,各组间红细胞数无显著差异。(5)1.8×10~8 CFU/g组的血清中胆固醇、葡萄糖和丙二醛含量显著低于对照组;1.5×10~7 CFU/g组血清中碱性磷酸酶活性显著高于对照组,而谷丙转氨酶和谷草转氨酶活性显著低于对照组。综上所述,吉富罗非鱼(50~210 g)饲料中粪肠球菌的适宜添加浓度范围为7.5×10~7~1.1×10~8 CFU/g,但添加粪肠球菌对血液载氧能力有负面影响。

Effects of Enterococcus faecalis on growth performance, body composition, blood physiological and biochemical indexes and digestive enzyme of GIFT tilapia (Oreochromis niloticus)

This experiment was conducted to investigate the effects of Enterococcus faecalis on growth performance, body composition, digestive ability and blood physiological and biochemical parameters of GIFT tilapia (Oreochromis niloticus). 300 fish of initial body weight (50.59±0.59)g were randomly divided into 5 groups, and each group was fed to triplicate repeats of 20 fish for 60 days. Each group was fed five isonitrogenous (crude protein 36%) and isolipidic (ether extract 6.75%) diets which added respectively 1.3×10²(control), 1.4×10⁵, 1.7×10⁶, 1.5×10⁷and 1.8×10⁸ CFU/g (measured) E. faecalis. The results showed as follows: Compared with control group, the final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR) and feed intake (FI) in the group of 1.5×10⁷ CFU/g reached a maximum and were significantly increased, and the feed conversion ratio (FCR) in this group was significantly reduced. Based on FBW, WGR and SGR, quadratic regression analysis projected the optimal concentration range for GIFT tilapia feed to 7.5×10⁷-1.1×10⁸ CFU/g. Compared with control group, the whole body crude protein content in all addition groups was significantly increased, and the whole body crude fat content in the group of 1.5×10⁷ CFU/g was significantly increased, there was not significant difference of the whole body moisture and crude ash content among all groups. The dry matter, protein, fat and ash deposition rate in the group of 1.5×10⁷ CFU/g are significantly higher than the control group. Compared with control group, the intestinal lipase activity was significantly increased in the group of 1.5×10⁷ CFU/g and 1.8×10⁸ CFU/g and intestinal protease activity was significantly reduced in the group of 1.8×10⁸ CFU/g. Adding E. faecalis to feed had no significant effect on intestinal amylase activity. The mean corpuscular volume, hemoglobin concentration and the number of platelets in the group of 1.5×10⁷ CFU/g are significantly lower than the control group. The erythrocyte count was not significantly different among all groups. The serum cholesterol, glucose content and the content of malonaldehyde in the group of 1.8×10⁸ CFU/g were significantly reduced compared with control group. Compared with control group, the activity of alkaline phosphatase in the group of 1.5×10⁷ CFU/g was significantly increased, but the activities of glutamic pyruvic transaminase and glutamic pyruvic transaminase in this group were significantly reduced. In conclusion, the suitable concentration range of E. faecalis for GIFT tilapia feed is 7.5×10⁷-1.1×10⁸ CFU/g, but adding E. faecalis has an adverse effect upon the ability of carrying oxygen of blood.