饲料蛋白水平对达氏鲟幼鱼生长性能、体组成、消化酶活性以及血液生化指标的影响

为了解达氏鲟(Acipenser dabryanus)幼鱼适宜的饲料蛋白质水平,试验选取平均初始体重为(400.68±8.55)g的健康达氏鲟幼鱼为试验对象,在室内流水系统中进行为期8周的摄食生长实验。试验鱼随机分为5组,每组3个重复,每个重复30尾鱼,分别饲喂蛋白质水平为30%、35%、40%、45%、50%的5种等脂等能饲料。试验期间,水流量为6 L/min,水温(24.0±1.0)℃,溶氧大于6.0 mg/L,氨氮小于0.02 mg/L。结果显示:增重率随饲料蛋白水平的增加呈现先升高后降低的趋势,饲料系数呈现相反的趋势。蛋白质效率随饲料蛋白水平的增加呈先平缓后下降的趋势。各试验组间肥满度无显著差异。肝体比和脏体比随饲料蛋白水平的增加而下降。各试验组间甘油三酯和总胆固醇含量无显著差异,饲料蛋白水平为50%的试验组的谷丙转氨酶(ALT)和谷草转氨酶(AST)活力显著高于其他试验组。本试验中胃蛋白酶活力与饲料蛋白水平呈正相关关系,淀粉酶活力呈负相关关系,脂肪酶在各试验组无显著差异。鱼体蛋白和脂肪含量均随饲料蛋白水平的增加而增加。分别对增重率、饲料系数这二者与饲料蛋白水平之间的关系进行二次回归分析,得出达氏鲟幼鱼饲料中适宜的蛋白水平为41.5%~42.97%。

Effects of dietary protein level on growth performance,body composition,digestive enzyme activities and blood biochemical parameters of juvenile Acipenser dabryanus

An 8-week growth trail was conducted to estimate the optimal dietary protein level for juvenile Acipenser dabrya-nus(average initial weight was (400. 68 ± 8. 55) g). Five isoenergetic diets were formulated to contain five levels of crude protein (30%, 35%, 40%, 45%, 50%) and each diet was fed to triplicate groups of thirty fish in fifteen concrete tanks. The flow rate was 6 L/min. The water temperature was 24. 0 ± 1. 0 ℃, dissolved oxygen concentration was over 6. 0 mg/L, ammonia-nitrogen concentration was less than 0. 02 mg/L during the trial. The results showed that weight gain rate increased firstly and then decreased with the increasing of dietary protein level. Feed conversion rate decreased firstly and then increased with the increasing of dietary protein level. Protein efficiency ratio showed a tendency of indifference firstly then decreasing with increasing of dietary protein level. Condition factor showed no significant difference. Viscerosomatic index and hepatosomatic index decreased significantly with the increasing of dietary protein level. The content of plasma triglyceride and total cholesterol showed no significant difference. The activities of ALT and AST which fed 50% dietary protein level showed significantly higher value than other group. The experiment showed that the dietary protein level has a positive correlation with pepsase activities and a negative correlation with amylase activities, while there is no significant difference with lipase activities. The content of crude protein and lipid in the whole body and dorsal muscle increased with the increasing of dietary protein level. Comprehensive regression analysis of weight gain rate and feed conversion rate showed that the appropriate dietary protein requirement of juvenile A. dabryanus is on a scale of 41. 5% to 42. 97%.