北方须鳅幼鱼的饲料蛋白质需求量

为确定北方须鳅幼鱼对饲料蛋白质的需求量,进行了为期60 d的生长试验。以鱼粉、发酵豆粕和酪蛋白作为蛋白质源,设计了蛋白质水平分别为22.85%、31.09%、40.72%、47.21%和54.08%的5种等脂等能试验饲料。每种饲料设3个重复,每个重复放养平均体重为(0.77±0.02)g的北方须鳅幼鱼40尾,以重复为单位养殖于水体为80 cm×50 cm×20 cm的水槽中。结果表明:饲料蛋白质水平为22.85%~40.72%时,随着饲料蛋白质水平的升高,增重率和特定生长率显著升高(P0.05);再继续升高饲料蛋白质水平,增重率和特定生长率反而显著降低(P0.05)。在饲料蛋白质水平为22.85%~40.72%时,饲料转化效率和存活率随着饲料蛋白质水平的升高呈升高趋势;当饲料蛋白质水平为40.72%~54.08%时,饲料转化率和存活率随着饲料蛋白质水平的升高呈下降趋势。在饲料蛋白质水平为40.72%时,试验鱼获得最高的增重率、特定生长率、饲料转化效率和存活率。饲料蛋白质水平对北方须鳅幼鱼的肥满度、脏体比、肝体比以及全鱼粗蛋白质和水分含量均未产生显著影响(P0.05)。饲料蛋白质水平高于40.72%后,全鱼粗脂肪含量显著降低(P0.05),并且饲料蛋白质水平为31.09%~54.08%时全鱼粗脂肪含量随着饲料蛋白质水平的升高而下降。由增重率与饲料蛋白质水平建立二次回归方程,得出北方须鳅幼鱼达到最大生长速度时的饲料蛋白质需求量为41.57%。

Dietary Protein Requirement of Barbatula barbatula nuda Juvenile

A 60?day feeding trial was conducted to investigate the dietary protein requirement of Barbatula bar?batula nuda juvenile. Fish meal, fermented soybean meal and casein were used as the protein sources to formu?late 5 isolipidic and isocaloric experimental diets containing different protein levels of 22. 85%, 31. 09%, 40.72%, 47.21% and 54.08%, respectively. Triplicate tanks were assigned to each experimental diet, and 40 fish with initial body weight of (0.77±0.02) g were assigned to each tank (water body volume: 80 cm× 50 cm×20 cm). The result showed as follows: when dietary protein levels were 22.85% to 40.72%, the weight gain rate ( WGR) and special growth rate ( SGR) were significantly increased with the dietary protein level increasing ( P<0.05) , but continued to increase the dietary protein level, the WGR and SGR were signif?icantly decreased ( P<0.05) . When dietary protein levels were 22.85% to 40.72%, the feed efficiency ( FE) and survival rate ( SR) showed increase trends with the dietary protein level increasing; when dietary protein levels were 40.72% to 54.08%, the FE and SR showed decrease trends with the dietary protein level increas?ing. The WGR, SGR FE and SR of Barbatula barbatula nuda juvenile reached the maximum values when diet?ary protein level was 40. 72%. Condition factor ( CF), viscerosomatic index ( VSI), hepatosomatic index ( HSI) and the contents of whole body moisture and crude protein were not significantly affected by dietary protein level ( P>0.05) . The crude lipid content of whole body was significantly decreased when dietary pro?tein level was over 40.72% ( P<0.05) , it was decreased with the dietary protein level increased from 31.09%to 54.08%. Base on the quadratic regression equation of WGR and dietary protein level, dietary protein re?quirement of Barbatula barbatula nuda juvenile to reach the maximum growth rate is 41.57%.