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以鱼粉和晶体氨基酸为蛋白源,制作7组缬氨酸梯度水平分别为6.3、7.2、8.9、11.0、12.6、14.1、15.8 g/(kg干饲料)的等氮等能半精制饲料,饲喂初始体质量为1.35 g的草鱼鱼种75 d,结果表明:草鱼鱼种增重率随饲料缬氨酸水平的提高而显著增加,当饲料缬氨酸水平达12.6 g/(kg干饲料)时草鱼鱼种增重率达最大值,继续增加饲料缬氨酸水平,草鱼鱼种增重率显著下降(P<0.05)。草鱼鱼种蛋白质累积率表现出与增重率相同的趋势。草鱼鱼种饲料效率在饲料缬氨酸水平为12.6、14.1 g/(kg干饲料)时达最大值(P<0.05)。饲料缬氨酸水平对草鱼鱼种鱼体必需氨基酸、支链氨基酸、总氨基酸含量及体组成无显著影响(P>0.05)。草鱼鱼种肝脏谷丙转氨酶活性在饲料缬氨酸水平为11.0 g/(kg干饲料)时达最高值(P<0.05),但各组之间并无明显规律性,饲料缬氨酸水平对草鱼鱼种肝脏谷草转氨酶活性无显著影响(P>0.05)。分别以鱼体增重率、蛋白质累积率和饲料效率为指标,以抛物线回归模型分析,求得草鱼鱼种对饲料缬氨酸的需求量为12.79~13.68 g/(kg干饲料),占饲料蛋白的3.76%~4.02%。
Seven kinds of equal nitrogen semi-refined forage with the valine gradient levels of 6.3, 7.2, 8.9, 11.0, 12.6, 14.1 and 15.8 g / (kg dry feed) were made from fish meal and crystal amino acids The results showed that the weight gain rate of grass carp increased significantly with the increase of feed valine level. When the feed valine level reached 12.6 g / (kg dry feed) Grass carp species weight gain rate reached the maximum, continue to increase feed valine levels, grass carp species weight gain rate decreased significantly (P <0.05). The protein accumulation rate of grass carp fingerlings showed the same tendency as the rate of weight gain. The feed efficiency of grass carp fingerlings reached the maximum (P <0.05) at the feed valine level of 12.6 and 14.1 g / (kg dry feed). The dietary valine level had no significant effect on the essential amino acids, branched-chain amino acids, total amino acid content and body composition of grass carp fingerlings (P> 0.05). The liver alanine aminotransferase activity in grass carp fingerlings reached the highest value at the dietary valine level of 11.0 g / (kg dry feed) (P <0.05), but there was no obvious regularity among the groups. Feed valine level There was no significant difference in activity of aspartate aminotransferase in grass carp fingerlings (P> 0.05). According to the weight gain rate, protein accumulation rate and feed efficiency, the parabola regression model was used to determine the dietary feed requirement of grass carp, which was 12.79 ~ 13.68 g / (kg dry feed) 3.76% ~ 4.02% of protein.