投喂策略对黄颡鱼生长和繁殖的影响

FEEDING STRATEGIES ON GROWTH AND REPRODUCTION OF YELLOW CATFISH (PELTEOBAGRUS FULVIDRACO)

  • 摘要: 实验设置饱食投喂(AS)、80%饱食(80AS)、50%饱食(50AS)及先饥饿34d后再饱食投喂31d (HAS)四个处理组, 饲养初重(86.6±0.41) g的雌性黄颡鱼(Pelteobagrus fulvidraco) 65d, 于实验中期(34d)和实验结束时取样, 以探究投喂策略对黄颡鱼母本生长性能和繁殖能力的影响。实验结果显示: 80AS组、50AS组和HAS组的总摄食量基本符合实验设计的比例且显著低于AS组。在实验结束时, 80AS组的增重率和体重与AS组无显著差异, HAS组体重显著低于AS组并与80AS组无显著差异, 生长未能达到同期饱食水平。各组在实验结束时的肌肉粗脂肪和粗蛋白含量均随投喂水平降低而降低, 性腺粗脂肪和粗蛋白则无显著差异, 据此可以推测母本将营养优先供给性腺而非肌肉。实验末期AS组和80AS组卵直径无显著差异, 均显著高于50AS组并低于HAS组, 表明饥饿后恢复摄食对卵的发育有补偿效应。实验结束时各处理组的绝对繁殖力和相对繁殖力未受到投喂策略的显著影响。80AS、50AS及HAS组的star、sf-1、3β-hsdcyp19a1基因表达由中期的显著低于AS组上调至末期的与AS组无显著差异, 而血浆雌二醇和睾酮含量的变化趋势与上述基因表达相一致。这说明80AS、50AS和HAS组的性激素合成、分泌及性腺发育仅在早期受到投喂策略的抑制, 末期抑制作用解除, 各组相关指标恢复。综合各项数据表明, 80AS组各项生长、繁殖指标与AS组无显著差异, 且摄食量显著低于AS组, 为繁殖期较为适宜的投喂策略。HAS组虽然生长低于AS组, 但繁殖能力与AS组无差异, 说明黄颡鱼饥饿后恢复摄食优先对繁殖力而非生长进行补偿。

     

    Abstract: Most of feeding strategies which maximize the feeding rate are just designed for fish farming but not suitable for broodfish. Overfeeding caused by these feeding strategies will even impair the reproductive performance. However, moderate feed restriction can maintain fecundity while lowering breeding costs. Feeding strategies based on compensatory growth may promote growth and fecundity of broodfish, or make them mature faster. To test the effects on growth and reproductive capacity of female yellow catfish Pelteobagrus fulvidraco, fish were fed with four groups for 67 days: satiety feeding (AS), 80% satiety (80AS), 50% satiety (50AS) and starvation for 35 days and then satiety feeding for 31 days (HAS). Samples were taken at the middle (34 days) and the end of the experiment and various indexes were measured in this time. Results showed that the total food intake of the 80AS, 50AS and AS group roughly conforms to the proportion of the experimental design. The daily food intake of the HAS group was the highest. No significant difference was observed in weight gain rate and final weight between the 80AS group and the AS group. Meanwhile, the final weight of the HAS group was significantly lower than that of AS group, which shows the growth of the HAS group failed to reach those who fed at satiety level in the same period. As the serum lipid and protein concentrations increased in each group, the retention of lipid and protein in gonad increased. It can be inferred that parent fish preferentially transmit nutrition to gonads rather than muscles. There was no significant difference in final egg diameter between the AS group and 80AS group, which were significantly higher than the 50AS group and lower than the HAS group, indicating that the refeeding has a compensatory effect on egg growth. Feeding strategy did not impact absolute fecundity and fecundity, but alterd the expression of genes which related to gonad development. The relative expression of StAR, SF-1, 3β-hsd and cyp19a1 in the 80AS, 50AS and HAS was significantly lower than that in AS group in the middle stage. Nevertheless, no significant difference was found between these group and AS group in the end stage. The trend of plasma estradiol and testosterone was consistent with the above expression of genes, indicating that the synthesis and secretion of sex hormones and gonadal development in 80AS, 50AS and HAS groups were only inhibited by feeding strategy in the early stage. Finally, the inhibition effect was relieved, and the relevant indexes of each group recovered. These may be the result of interaction between the stress response and reproduction of broodfish. Based on the data above, satisfying the material and energy needs of gonadal development has priority in yellow catfish’s resource allocation. Although the growth of HAS group was lower than that of AS group, there was no difference in reproductive ability between HAS group and AS group, indicating that parent Pelteobagrus fulvidraco mainly compensated for fecundity rather than growth after starvation. Therefore, it is necessary to redesign the feeding strategy based on compensatory growth according to the physiological characteristics which need further exploration to improve the fecundity of Pelteobagrus fulvidraco broodfish. The growth and reproduction indexes of 80AS group were not significantly different from those of AS group, and the food intake was significantly lower than that of AS group, which was a more suitable feeding strategy in the breeding period of yellow catfish.

     

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