棉籽浓缩蛋白替代鱼粉对鳜生长和健康的影响及营养恢复期补偿生长效应

Effect of fishmeal replacement with cottonseed protein concentrate on growth, health, and post-nutritional recovery compensatory growth in Siniperca chuatsi

  • 摘要:
    目的 为探究鳜对棉籽浓缩蛋白(CPC)耐受阈值和不同水平CPC替代鱼粉对鳜生长性能、饲料利用、肝肠健康的影响,以及营养恢复期的补偿生长效应机制,
    方法 以含50%鱼粉和5.9% CPC的基础饲料为对照组,制作替代0%(CF0)、17.5%(CF17.5)、35.0%(CF35.0)、52.5%(CF52.5)、70.0%(CF70.0)鱼粉的5组等氮等脂饲料。选取初始体重为(34.47±0.07) g的幼鳜,随机分为5组,用上述5种饲料投喂6周后,改用对照组饲料进行6周的营养恢复饲养。
    结果 在CPC替代期,17.5%及以上的CPC替代显著降低了鳜的生长性能和饲料利用效率。棉酚通过抑制摄食、诱导氧化应激等,造成肠绒毛数量、肠绒毛分支数量降低,影响肠道紧密连接蛋白、炎症、免疫相关基因mRNA表达等削弱肠道屏障、引起了肠道炎症和免疫抑制,同时还造成了肝损伤,35%替代组肝脏抗氧化能力显著下降,血清转氨酶含量显著升高,并上调p53的mRNA表达,诱发了严重肝损伤,而70%替代组则可能通过激活自噬(becn1)和抑制凋亡(caspase-3)实现部分代偿性修复。在营养恢复期,鳜展现出补偿生长能力,通过调节igf-1、mtor、s6k、ampk、ppar-α等mRNA表达重构代谢,分别驱动“超合成代谢”、“模式适应性代偿策略”补偿生长,显著提高生长性能和饲料利用效率。
    结论 鳜对CPC的耐受较差,过高的替代水平会显著损伤鳜的肝肠健康并抑制生长。在恢复期,鳜通过调节能量代谢和生长相关信号通路实现补偿生长。本研究为鳜饲料中棉籽浓缩蛋白的高效利用提供了理论依据,并为水产养殖业精准营养管理策略的优化与创新提供科学支持。

     

    Abstract: Fishmeal replacement is crucial for promoting sustainable aquaculture, and cottonseed protein concentrate (CPC) is considered a promising plant protein source. Currently, the fishmeal constitutes over 50% of commercial diets for Siniperca chuatsi, highlighting the urgency of reducing its proportion to enhance the sustainability of aquaculture industry. This study investigated the tolerance threshold of S. chuatsi to CPC, as well as its effects on growth performance, feed utilization, liver and intestinal health, and compensatory growth during nutritional recovery. Juvenile S. chuatsi initial weight (34.47±0.07) g were fed isonitrogenous and isolipidic diets with fishmeal replaced by CPC at levels of 0% (CF0), 17.5% (CF17.5), 35.0% (CF35.0), 52.5% (CF52.5), and 70.0% (CF70.0) for six weeks, followed by a six-week nutritional recovery period with the control diet. Results showed S. chuatsi exhibited lower tolerance to CPC than other carnivorous fish species. Despite essential amino acid supplementation, CPC replacement at 17.5% (151.8 g/kg) or higher significantly reduced weight gain and specific growth rates, while increasing feed conversion ratio and protein efficiency ratio (P < 0.05). Growth and metabolism were disrupted, leading to a reduction in whole-body crude lipid content, hepatic Oil Red O staining and gonadosomatic index at all replacement levels of 17.5% or higher, as well as a decrease in perivisceral fat index specifically at the 70% replacement level (P < 0.05). At the transcriptional level, ampk, s6k, gh, igf-1 and lipid metabolism genes (srebp-1, fas, acc1) were significantly upregulated in CF35.0 and CF70.0 (P < 0.05), while npy and pomc exhibited brain-specific downregulation but were concurrently upregulated in CF35.0 and CF70.0 in the midgut (P < 0.05). Liver health declined at 35% replacement, with reduced SOD, CAT, and GPx activities and increased MDA, ALT, and AST levels (P < 0.05), accompanied by p53-mediated hepatocyte apoptosis, suggesting the occurrence of severe liver damage. In contrast, the 70% replacement group exhibited increased SOD, CAT, and GPx activities, decreased MDA, ALT, and AST levels (P < 0.05), and potential compensatory repair through becn1 upregulation and caspase-3 downregulation. CPC replacement also impaired intestinal health, significantly reducing villus height, width, and muscle layer thickness (P < 0.05). Tight junction protein genes (occludin, zo-1) were downregulated (P < 0.05) while nos1 was upregulated (P < 0.05), suggesting increased oxidative stress. Pro-inflammatory cytokines (tnf-α, il-1β) were downregulated (P < 0.05), indicating potential inflammation suppression and immune inhibition. Digestive enzyme activity increased at low replacement levels but declined with further CPC inclusion (P < 0.05). After six weeks of nutritional recovery, weight gain rate, specific growth rate, and protein efficiency linearly increased with prior CPC replacement levels, while the feed conversion ratio decreased linearly (P < 0.05), demonstrating a typical compensatory growth pattern. Villus number, length, width, and muscle layer thickness increased, suggesting improved digestive and absorptive capacity. The CPC35.0 group demonstrated a synthesis-dominant metabolic mode, characterized by the significant upregulation of mtor, igf-1, srebp-1, and fas (P < 0.05), leading to lipid accumulation and vacuolation. In contrast, the CPC70.0 group showed sustained upregulation of mtor/s6k during nutritional recovery (P < 0.05), where as igf-1, srebp-1, and fas returned to control levels (P > 0.05). Meanwhile, pcna and ccnd1 were significantly upregulated (P < 0.05), enhancing hepatocyte proliferation and tissue repair. Reactivated ampk upregulated ppar-α (P < 0.05), promoting fatty acid oxidation and restoring hepatocyte morphology. The hepatosomatic index (HSI) significantly increased (P < 0.05), indicating restored hepatic energy reserves. The study indicated that CPC replacement at 17.5% or higher significantly impacted growth, feed utilization, and liver-intestinal health in S. chuatsi. However, during nutritional recovery, S. chuatsi displayed compensatory growth, with weight gain rate, specific growth rate, and protein efficiency increasing with prior CPC replacement levels. Through metabolic remodeling and energy redistribution, growth and tissue repair were effectively restored. These findings provide insights into CPC as an alternative to fishmeal and its significance in developing precision nutrition strategies for sustainable aquaculture.

     

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