饲料蛋白水平对方格星虫稚虫生长和体组成的影响

以初始体重为39.20±0.24mg的方格星虫稚虫为实验对象,分别饲喂蛋白水平为25.21%、29.87%、35.03%、40.67%、45.47%、50.12%、55.29%、60.38%、64.85%的9种等能微颗粒饲料56d,研究饲料蛋白水平对方格星虫稚虫生长和体组成的影响。结果表明,饲料蛋白水平对方格星虫稚虫的生长性能有显著影响(P<0.05)。随着饲料中蛋白水平的提高,稚星虫的增重率和特定生长率都呈先增后降的趋势,当饲料蛋白水平为45.47%时,稚星虫增重率和特定生长率均达到最大值,二次曲线回归分析确定当增重率达到极值时,饲料蛋白水平为46.79%;对稚星虫体组成成分的分析表明,饲料蛋白水平对方格星虫稚虫体组成中脂肪和蛋白质的含量影响显著(P<0.05),稚星虫体蛋白含量随着饲料蛋白水平的上升有显著升高的趋势,64.85%组稚星虫体蛋白含量最高,显著高于其他各蛋白水平组(P<0.05)。体脂肪含量随着饲料蛋白水平的上升有降低的趋势,64.85%组稚星虫的体脂肪含量最低,显著低于25.21%、29.87%、35.03%和40.67%组(P<0.05)。饲料蛋白水平对稚星虫体灰分含量没有显著影响(P>0.05)。以增重率为评价指标时,方格星虫稚虫对饲料中蛋白的适宜需求量为46.79%。

Effects of dietary protein level on growth performance and body composition of juvenile peanut worm, Sipunculus nudus Linnaeus

Sipunculus nudus Linnaeus at an average body weight of 39.20±0.24 mg were divided into 9 groups with triplicates and 500 larvae in each replicate to investigate the effects of dietary protein level on growth performance and body composition of juvenile peanut worm, S. nudus,by feeding diets with 9 protein levels (25.21%, 29.87%, 35.03%, 40.67%, 45.47%, 50.12%, 55.29%, 60.38%,and 64.85%) for 8 weeks. The results showed that protein level significantly affected growth performance of S. nudus larvae (P<0.05). With the increasing dietary protein level, the weight growth ratio (WGR) and specific growth ratio (SGR) firstly increased and then decreased, and when the dietary protein level was 45.47%, both WGR and SGR produced the maximum value. The regression model analysis showed the best dietary protein level was 46.79%,at which the best WGR was acquired. The results of body composition analysis showed that dietary protein level had significant effects on body protein content (P<0.05), which increased with the increasing doses of dietary protein. S. nudus fed with 64.85% protein produced the highest body protein content, and was significantly different from the groups with other protein levels (P<0.05). There was a downward trend in body lipid content, and when the dietary protein level was 64.85%, the body lipid content was significantly lower than that in groups with 25.21%, 29.87%, 35.03% and 40.67% protein (P<0.05). The dietary protein level had no significant effects on body ash content (P>0.05). Based on comprehensive analysis of WGR, it was concluded that the suitable dietary protein level for S. nudus larvae should be 46.79%.