克氏原螯虾的脂肪需求量及饲料中脂肪与糖类适宜比例的研究

Fat Requirement and Optimal Dietary Fat to Carbohydrate Ratio for Red Swamp Crayfish(Procambarus clarkii)

为研究克氏原螯虾(Procambarus clarkii)饲料中脂肪的适宜水平以及脂肪与糖类的适宜比例,以菜籽粕、鱼粉、豆粕、面粉和糊精等为主要原料配制5种等氮(蛋白质水平约为35%)等能(消化能约为13 MJ/kg)的半纯合饲料,分别饲喂5组平均体重为(8.15±0.03)g的克氏原螯虾幼虾,每组4个重复,每个重复20尾。5种饲料的脂肪水平(%)/糖类水平(%)分别为3/36.94(A1组)、5/34.15(A2组)、7/26.98(A3组)、9/24.56(A4组)和11/21.85(A5组)。试验期为40 d。结果表明:随着饲料中脂肪与糖类比例的增加,各组的存活率先上升后下降,A1组显著低于其他各组(P<0.05),A2组显著高于A1和A5组(P<0.05)。饲料系数和摄食率各组之间无显著差异(P>0.05)。增重率与特定生长率A2、A3和A4组之间差异不显著(P>0.05),但A2、A3和A4组的增重率显著高于A1组(P<0.05),特定生长率显著高于A1和A5组(P<0.05)。A5组的蛋白质效率最低,显著低于A2组(P<0.05)。肌肉中水分、粗灰分和粗蛋白质含量均以A5组为最高,显著高于A2组(P<0.05),与A3和A4组差异不显著(P>0.05)。肌肉中粗脂肪、钙和磷含量各组之间无显著差异(P>0.05)。随着饲料中脂肪水平的提高,血清脂蛋白脂酶活力呈现先上升后下降的趋势,肠道中淀粉酶活力则呈现先下降后上升的趋势,极值均出现在A3组。综合以上试验结果认为,在本试验条件下,初始体重为(8.15±0.03)g的克氏原螯虾对脂肪的需求量在7%左右,饲料中脂肪与糖类的适宜比例为1.00∶3.85。

In order to study the optimum fat level and fat to carbohydrate ratio in the diet for red swamp cray- fish （Procambarus clarkii） , five groups of red swamp crayfish shrimps with an average initial body weight of （8.15 ±0.03 ） g were fed with five isonitrogenous （protein level was about 35% ） and isocaloric （digestive energy was about 13 MJ/kg） semipurified diets, mainly including fish meal, rapeseed meal, soybean meal, flour and dextrin. Each group had 4 replicates and each replicate had 20 shrimps. The fat level （ % ）/carbohy- drate level （ % ） of the five diets were 3/36.94 （ A1 ） , 5/34.15 （A2） , 7/26.98 （A3） , 9/24.56 （A4） and 11/21.85 （A5）, respectively. The experiment lasted for 40 days. The results showed as follows： the survival rate was firstly increased and then decreased with the dietary fat and carbohydrate ratio increasing, and that in A1 group was significantly lower than that in other groups （ P 〈 0.05 ）, while that in A2 group was significant- ly higher than that in A1 and A5 groups （ P 〈 0.05 ）. Feed conversion ratio and feeding rate had no significant differences among all groups （ P 〉 0.05 ）. No significant differences were found in weight gain rate and specif- ic growth rate among A2, A3 and A4 groups （ P 〉 0.05 ）, but the weight gain rate in A2, A3 and A4 groups was significantly higher than that in A1 group （ P 〈 0.05 ） , and specific growth rate in A2, A3 and A~ groups was significantly higher than that in A1 and A5 groups （ P 〈 0.05 ）. Protein efficiency ratio in A5 group was the lowest, and significantly lower than that in A2 group （ P 〈 0.05 ）. The highest contents of moisture, ash and crude protein in muscle were all found in A5 group, and those in A5 group were significantly higher than those in A2 group （ P 〈 0.05 ）, but there was no significant differences among A3, A4 and A5 groups （ P 〈 0.05 ）. No significant differences were found in the contents of ether extract, calcium and phosphorus in mus- cle among all groups （ P 〉 0.05 ）. With the increase of fat to carbohydrate ratio, serum lipoprotein lipase ac- tivity was firstly increased and then decreased, while intestinal amylase activity was firstly decreased and then increased, and the extreme values of them were all found in A3 group. According to above results, it is con- cluded that the requirement of fat is about 7%, and the optimal dietary fat to carbohydrate ratio is 1.00：3.85 for the red swamp crayfish with the average initial body weight of （8.15 ±0.03 ） g under this experimentalcondition.