黄鳝饲料蛋白质需求量的研究

REQUIREMENT LEVEL OF DIETARY PROTEIN FOR MONOPTERUS ALBUS

  • 摘要: 为确定黄鳝(Monopterus albus)对饲料蛋白质的需求量, 试验分7组, 每组4个重复。每个重复放养初始体重为(17.1±0.2) g的幼鳝25尾, 分别以鱼粉和酪蛋白为主要蛋白源, 配制蛋白质含量为32.74%(T1)、38.50%(T2)、42.26%(T3)、48.35%(T4)、52.65%(T5)、57.87%(T6)和62.31%(T7)的7种等能不等氮饲料, 养殖期为60d。以生产性能、蛋白质保留率和生理生化指标等综合评价确定蛋白质的需求量。结果: (1)随饲料蛋白质含量升高, 饲料系数呈先降低后升高; 增重率(WGR)、特定生长率(SGR)、蛋白保留率(PRR)与蛋白质效率(PER)先升高后降低; 饲料蛋白质含量57.87%组获得最好的生长性能, 52.65%组蛋白质保留率最高。(2)随饲料蛋白质含量升高, 黄鳝血清中尿素氮(BUN)含量升高, 谷丙转氨酶(ALT)和谷草转氨酶(AST)的活性先降低后保持稳定, 总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)及血糖(GLU)含量降低; 丙二醛(MDA)含量呈现先降低后升高的趋势, 在52.65%时最低。(3)随饲料蛋白质含量升高, 黄鳝肝胰脏、胃和肠蛋白酶活性先显著上升后呈缓慢上升趋势; 肝胰脏脂肪酶活性先显著下降后呈缓慢下降趋势, 胃和肠脂肪酶活性各试验组之间无显著性差异; 胃淀粉酶活性无显著差异, 肝胰脏和肠呈先显著下降后缓慢降低的趋势。综上: 当饲料蛋白质含量低时, 黄鳝会加大摄食量满足蛋白质需求, 在饲料蛋白质含量过高时, 氧化应激增加, 黄鳝通过降低摄食量减少蛋白质摄入。以WGRPERSGR及饲料系数(FCR)为评价指标确定幼鳝对饲料蛋白质的适宜需求量为48.51%—52.60%。

     

    Abstract: The study was aimed to determine the requirement level of dietary protein for ricefield eel (Monopterus albus). The experiment was divided into 7 groups, with 4 replicates in each group. Each replicate included 25 ricefield eels with an initial weight of (17.1±0.2) g. The ricefield eels were fed seven isoenergetic diets respectively for 60d containing different levels of crude protein (32.74%, 38.50%, 42.26%, 48.35%, 52.65%, 57.87% and 62.31%) with fish meal and casein as the main protein source. Then the production performance, protein retention rate, physiological and biochemical indexes were evaluated to determine the requirement level of dietary protein. The results showed that 1) with the increase of feed protein level, the feed conversion ratio was decreased and then increased, but the weight gain rate, specific growth rate, protein efficiency ratio and protein retention rate increased first and then decreased. The growth performance was the highest in 57.87% of dietary protein group, and the protein retention rate was the best in 52.65% of dietary protein group. 2) with the increase of dietary protein level, the BUN in ricefield eel serum increased, the activities of GPT and GOT in ricefield eel serum decreased and then remained unchanged, the contents of TC, TG, HDL-C, LDL-C and blood glucose decreased, and the MDA content in ricefield eel serum decreased first and then increased, which was the lowest in 52.65% of dietary protein level. 3) With the increase of dietary protein level, the protease activities in liver, stomach and intestine of ricefield eel increased significantly and then increased slowly, the lipase activity in liver decreased significantly and then decreased slowly, the lipase activities in stomach and intestinal showed no significant difference, and the amylase activities showed no significant difference in stomach which decreased significantly first and then decreased slowly in liver and intestinal. These results indicated that ricefield eels will increase the feeding to supplement the protein requirement with low level of dietary protein. While the level of dietary protein was too high, the oxidative stress increased, thus ricefield eels will reduce the protein intake by reducing food intake. With the regression analysis of weight gain rate, protein efficiency ratio, protein retention rate and feed conversion ratio, the appropriate requirement level of dietary protein for ricefield eels is 48.51%—52.60%.

     

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