啤酒酵母粉替代部分鱼粉对牛蛙生长、抗氧化能力以及肝脏和肠道组织形态学的影响

Effects of Partially Replacing Fish Meal with Brewer's Yeast Meal on Growth,Antioxidant Capacity,and Liver and Intestine Tissue Morphology of Bullfrog [Rana( Lithobates) catesbeiana]

本试验旨在研究啤酒酵母粉替代部分鱼粉对牛蛙生长性能、体组成、肝脏抗氧化指标、血清生化指标、肠道消化酶活性以及肝脏和肠道组织形态学的影响。选取初始体重为(34.15±1.10) g的牛蛙135只,随机分为3组,每组3个重复,每个重复15只。以含20%鱼粉的饲料为对照饲料,用啤酒酵母粉分别替代对照饲料中25%(Y25%)和50%的鱼粉(Y50%),配制3种等氮等脂的试验饲料,进行为期8周的生长试验。结果显示:用啤酒酵母粉替代25%或50%的鱼粉后牛蛙的各生长性能指标均没有受到显著影响(P>0.05)。2个替代组蛙体水分含量显著高于对照组(P<0.05),蛙体粗灰分含量显著低于对照组(P<0.05),而蛙体粗蛋白质和粗脂肪含量则与对照组无显著差异(P>0.05)。对照组和Y25%组干物质和粗蛋白质的表观消化率均显著高于Y50%组(P<0.05)。粗脂肪的表观消化率随着啤酒酵母粉替代水平的升高而显著降低(P<0.05),而磷的表观消化率则随着啤酒酵母粉替代水平的升高而显著升高(P<0.05)。啤酒酵母粉替代25%或50%的鱼粉对牛蛙血清中谷草转氨酶(AST)、谷丙转氨酶(ALT)的活性均无显著影响(P>0.05),Y50%组血清碱性磷酸酶(ALP)、溶菌酶(LZM)活性显著高于对照组(P<0.05)。Y25%和Y50%组肝脏中总抗氧化能力(T-AOC)显著高于对照组(P <0.05)。肝脏中总超氧化物歧化酶(T-SOD)与过氧化氢酶(CAT)活性以及还原型谷胱甘肽(GSH)含量均随啤酒酵母粉替代水平的升高而显著升高(P<0.05)。2个替代组肠道蛋白酶、脂肪酶活性均显著低于对照组(P<0.05),而肠道淀粉酶活性则与之相反。组织学观察发现各组肝脏和肠道组织结构未见明显异常,但2个替代组肝细胞脂肪沉积较对照组减少。肝脏中胰岛素样生长因子-Ⅰ(IGF-Ⅰ)基因的相对表达量各组间没有显著差异(P> 0.05),但2个替代组肝脏中热休克蛋白70(HSP70)基因的相对表达量显著高于对照组(P<0.05)。综上,啤酒酵母粉是牛蛙饲料中优质的蛋白质源,其替代鱼粉水平不超过50%时可维持牛蛙正常的生长性能,并有利于维护肝脏健康。

An 8-week feeding trial was carried out to evaluate the effects of partially replacing fish meal( FM)with brewer’s yeast meal( BYM) on growth performance,body composition,liver antioxidant indexes,serum biochemical indexes,intestine digestive enzyme activities,liver and intestine tissue morphology of bullfrog [Rana( Lithobates) catesbeiana]. A total of 135 bullfrogs with an initial body weight of( 34.15±1.10) g were randomly divided into 3 groups with 3 replicates per group and 15 bullfrogs per replicate. Three isonitrogenous and isolipidic diets were formulated. A control diet was formulated to contain 20% FM first,and then two other diets were prepared by substituting 25%( Y25%) or 50%( Y50%) of FM with BYM based on the control diet. The results showed that replacing 25% or 50% of FM with BYM did not significantly influence all growth performance indexes( P>0.05). The whole-body moisture content in two replacing groups was significantly higher than that in control group( P<0.05),and the whole-body crude protein and crude lipid contents had no significant differences compared with control group( P<0.05). The apparent digestibility coefficients of dry matter and crude protein in control group and Y25% group were significantly higher than those in Y50% group( P < 0.05). With the replacing level of BYM increasing,the apparent digestibility coefficient of crude lipid was significantly increased( P < 0.05),while the apparent digestibility coefficient of phosphorus was significantly decreased( P<0.05). Replacing25% or 50% of FM with BYM had no significant effects on serum aspartate aminotransferase( AST) and alanine aminotransferase( ALT) activities( P>0.05). The activities of serum alkaline phosphatase( ALP) and lysozyme( LZM) were significantly higher than those in control group( P<0.05). The liver total antioxidant capacity in Y25% and Y50% groups was significantly higher than that in control group( P<0.05). The activities of liver total superoxide dismutase( T-SOD) and catalase( CAT) and the content of liver reduced glutathione( GSH) were significantly increased with the replacing level of BYM increasing( P<0.05). Histological observation showed that there were no obvious abnormal changes in liver and intestinal tissue structure of each group,but fat deposition was reduced in hepatocyte of Y25% and Y50% groups compared with control group. The relative expression level of heat shock protein 70( HSP70) gene in liver in two replacing groups was significantly up-regulated compared with control group( P<0.05),while the relative expression level of insulin like growth factor-Ⅰ( IGF-Ⅰ) gene in liver was not significantly influenced by replacing FM with 25% or 50% BYM( P>0.05). According to the results,BYM can be used as a good protein source for bullfrog. Replacing FM with less than 50% BYM can keep regular growth performance and better liver health for bullfrog.