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分别用含6种水平(质量比分别为0.78%、0.95%、1.09%、1.34%、1.51%和1.72%)苯丙氨酸(phenylalanine,Phe)的等氮等能(粗蛋白30.10%,总能17.73 MJ/kg)饲料,在池塘网箱中(实验期间水温为24~32℃)饲喂初始体重为(52.70±1.80)g的吉富罗非鱼60 d,考察饲料Phe对吉富罗非鱼(GIFT,Oreochromis niloticus)生长性能、饲料系数、体成分、部分血清生化指标及前肠消化酶活性的影响,以期获得吉富罗非鱼对饲料苯丙氨酸的需要量。结果表明,随着饲料中Phe水平的升高,吉富罗非鱼的增重率、特定生长率、蛋白质效率、蛋白质沉积率、肥满度、肝体比和脏体比均呈现先上升后下降的趋势,饲料系数呈现先下降后上升的趋势;全鱼粗脂肪和全鱼灰分含量显著上升(P<0.05),肌肉灰分含量显著下降(P<0.05)。饲料中Phe对全鱼水分和粗蛋白质、肌肉水分、肌肉粗蛋白质和肌肉粗脂肪含量无显著性影响(P>0.05);各实验组的肌肉氨基酸含量差异不显著(P>0.05)。饲料中Phe显著影响血清中谷丙转氨酶活性,甘油三酯、总胆固醇和葡萄糖的含量(P<0.05),对谷草转氨酶活性无显著性影响(P>0.05);Phe显著影响肠蛋白酶、肠脂肪酶和肠Na~+-K~+-ATP酶活性(P<0.05),而对肠淀粉酶活性影响不显著(P>0.05)。以增重率、饲料系数和蛋白质效率为评价指标,通过二次回归分析可知,吉富罗非鱼对饲料中Phe需要量为1.17%~1.21%,占饲料蛋白质的3.89%~4.02%。本研究结果为合理配制吉富罗非鱼配合饲料提供了理论依据。
The isoflavones such as isoparaffin (30.10% crude protein, total protein content of crude protein, (17.73 MJ / kg) were fed into the pond cages (water temperature 24 ~ 32 ℃ during the experiment) to feed the tilapia (Tilapia tilapia) with the initial body weight of (52.70 ± 1.80) g for 60 days. (GIFT, Oreochromis niloticus) growth performance, feedstuff coefficient, body composition, partial serum biochemical indexes and foregut digestive enzyme activity in order to obtain the feed requirement of phenylalanine. The results showed that with the increase of dietary Phe level, the growth rate, specific growth rate, protein efficiency, protein deposition rate, fatness, liver body ratio and body weight ratio increased first and then decreased (P <0.05). The content of ash in muscle decreased significantly (P <0.05). The feedstuff coefficient showed the first decrease and then increased. The content of ash in whole fish and whole fish increased significantly (P <0.05). Phe had no significant effect on moisture and crude protein, muscle moisture, muscle crude protein and muscle fat content of whole fish (P> 0.05). There was no significant difference in muscle amino acid content among all experimental groups (P> 0.05). The dietary Phe significantly affected the activity of alanine aminotransferase, triglyceride, total cholesterol and glucose in serum (P <0.05), and had no significant effect on the activity of aspartate aminotransferase (P> 0.05). Phe significantly affected intestinal protease, intestinal lipase And intestinal Na ~ + -K ~ + -ATPase activity (P <0.05), but had no significant effect on intestinal amylase activity (P> 0.05). According to the quadratic regression analysis, the weight gain rate, feed conversion coefficient and protein efficiency were used as the evaluation indexes. The results showed that the feed requirement of Psyllium tilapia was 1.17% -1.21%, accounting for 3.89% ~ 4.02% of feed protein. The results of this study provide a theoretical basis for the rational formulation of Yoshitomi tilapia feed.