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为研究饲料中不同蛋白源对军曹鱼幼鱼碳、氮稳定同位素分馏的影响,配制3种等氮等能饲料。D1以鱼粉为蛋白源,D2和D3饲料中分别以啤酒酵母和玉米蛋白替代10%的鱼粉蛋白,投喂幼鱼24d。结果表明,啤酒酵母和玉米蛋白替代10%的鱼粉蛋白后,幼鱼的体质量增加率显著下降。随养殖时间的延长,所有处理组幼鱼的碳稳定同位素比率δ13C逐渐上升而氮稳定同位素比率δ15N逐渐下降;虽然全鱼和肌肉δ15N的变化速度存在差异,但各饲料组全鱼和肌肉的δ13C和δ15N都在24d后与饲料达到平衡。当饲料中10%的鱼粉蛋白被啤酒酵母和玉米蛋白替代之后,幼鱼肌肉和全鱼样品与饲料相比的碳同位素富集Δ13C值下降,而氮同位素富集Δ15N值则上升。其中全鱼Δ13C从4.19‰分别下降到3.94‰和3.63‰,肌肉Δ13C从4.46‰分别下降到3.98‰和3.67‰;全鱼Δ15N从0.18‰分别增加到0.88‰和0.94‰,肌肉Δ15N从0.18‰分别增加到0.74‰和0.87‰。军曹鱼在摄食3种不同蛋白源饲料时,其全鱼和肌肉的Δ13C和Δ15N的变化趋势相似,但全鱼δ15N的变化速度慢于肌肉。据此可推断,肌肉可在生态学营养级研究(长时间尺度)中代表军曹鱼的碳、氮同位素特征;但在代谢生理学研究中(短时间尺度),肌肉就无法准确反映军曹鱼全鱼的δ15N变化过程。
In order to study the effects of different protein sources in diet on carbon and nitrogen stable isotope fractionation of juvenile cobia juveniles, three kinds of equal nitrogen feedstuffs were prepared. D1 fish meal as protein source, D2 and D3 feed, respectively, brewer’s yeast and corn protein instead of 10% of fish meal protein, fed juvenile 24d. The results showed that after 10% fish meal protein was replaced by beer yeast and zein, the increase rate of body weight of juvenile fish decreased significantly. With the prolongation of the culture time, the δ13C of the stable fish and the δ15N of the stable nitrogen decreased gradually. The δ13N values of whole fish and muscle decreased And δ15N all reached equilibrium with feed after 24 days. When 10% of fishmeal protein in feed was replaced by S. cerevisiae and zein, the Δ13C value of carbon isotope enrichment in juvenile muscle and whole fish samples decreased compared with feed, while the nitrogen isotope enrichment Δ15N value increased. Among them, Δ13C in whole fish decreased from 4.19 ‰ to 3.94 ‰ and 3.63 ‰, while Δ13C in muscle decreased from 4.46 ‰ to 3.98 ‰ and 3.67 ‰, respectively; Δ15N increased from 0.18 ‰ to 0.88 ‰ and 0.94 ‰ respectively, while Δ15N increased from 0.18 ‰ Respectively, increased to 0.74 ‰ and 0.87 ‰. When feeding on three different protein sources, the changes of Δ13C and Δ15N of whole fish and muscle of cobia were similar, but δ15N of whole fish changed more slowly than that of muscle. It can be inferred that the muscle can represent the carbon and nitrogen isotope characteristics of cobia at the ecological trophic level (long time scale), but in the metabolic physiology (short time scale), the muscle can not accurately reflect the δ15N transformation.