管角螺幼螺配合饲料中蛋白质适宜含量的研究

Study on the appropriate protein content in compound feed of Hemifusus tubaLarvae

采用国产鱼粉+进口白鱼粉为蛋白源,混合油(鱼油∶豆油=1∶1)为脂肪源,设置了5个蛋白水平:25%、30%、35%、40%、45%(脂肪含量为9%)以特定生长率、饲料转化率和蛋白质效率为指标,在水温(29.7±1.9)℃,盐度24.5±2.5下,研究了上述不同蛋白质水平对管角螺的生长和肌肉成分的影响。选择壳高(2.25±0.25)cm、体重(0.65±0.25)g的管角螺,结果表明,随着蛋白质含量的上升,特定生长率、饲料转化率和蛋白质效率均呈抛物线变化趋势,分别在蛋白质水平为40%、40%和35%时取得最大值1.02%、60.1%和1.62%,且各组间差异性显著(P<0.05)。将特定生长率和饲料转化率分别与饲料蛋白质水平进行拟合,得出饲料蛋白质的最适含量分别为37.50%和38.88%。试验结束后对管角螺肌肉主要营养成分进行测定,发现随饲料蛋白质水平的增加,肌肉中粗蛋白和水分含量均增大,粗脂肪含量减小,且各组间差异性显著(P<0.05),粗灰分无显著性变化(P>0.05)。对肌肉氨基酸进行分析得出,饲料蛋白质水平不同,管角螺肌肉中的氨基酸含量也不同,蛋白质水平为45%组的氨基酸总量、必需氨基酸和鲜味氨基酸含量最多,25%组的最少,后者比前者分别少74.27%、17.47%和44.48%。EAA/TAA和EAA/NEAA略小于FAO/WHO,苯丙氨酸+酪氨酸是第一限制性氨基酸,蛋氨酸+胱氨酸为第二限制性氨基酸。

In this test, the domestic fishmeal and the white fishmeal were used as the protein sources, mixed oil （fish oil： soybean oil = 1 ： 1 ） as the fat source. The specific growth rate and feed conversion as well as the protein efficiency as the indexes were studied. At sea water temperature of 29.7℃ ±1.9℃ , salinity 24. 5±2.5, the effects at five protein grades（ 25% , 30% , 35% , 40% and 45% ） on the growth of Hemifusus tuba（Gmelin） and muscle composition were studied. The results showed that along with the protein content rising, the specifc growth rate, feed conversion and protein efficiency were present parabolic trend of change, and achieved the maxi- mum 1.02% , 60. 1% and 1.62% at the protein level of 40% , 40% and 35% , respectively. There was significant differences in groups （ P 〈 0. 05 ）. By fitting the feed protein level with the specific growth rate and feed conversion respectively, the optimum pro- tein content of Hemifusus tuba compound feed were 37.50% and 38.88% , respectively. After the test, the main nutrient components of the Hemifusus tuba muscle were determined. With the increasing of feed protein content, crude protein and moisture content in- creased, crude fat content decreased and there was significant difference in groups （P 〈 0. 05） , crude ash had no significant change （ P 〉 0.05 ）. Phenylalanine ＋ tyrosine is the first limiting amino acid, methionine ＋ cystine for the second limiting amino acids. By the analysis of the muscle fatty acid, the fatty acid content in Hemifusus tuba muscles was different with the different feed protein content. EAA / TAA and EAA / NEAA were slightly less than that of the FAO / WHO.