Palstra Arjan P, Roque Ana, Kruijt Leo, Jéhannet Pauline, Pérez-Sánchez Jaume, Dirks Ron P
Wageningen University & Research Animal Breeding and Genomics, Wageningen Livestock Research, Wageningen, Netherlands.
IRTA-SCR, Sant Carles de la Rapita, Spain.
Front Physiol. 2020 Dec 7;11:610049. doi: 10.3389/fphys.2020.610049. eCollection 2020.
A longer on-land rearing period of Gilthead seabream before transfer to sea-cages would allow the farmer to benefit from exercise-enhanced growth, resilience, and robustness as induced by increasing water flow in the tanks. In this study, the physiological effects of flow-conditioning were investigated by subjecting large groups of experimental fish to minimal flow or to flow regimes inducing swimming exercise at 1 or 2 body length (BL) s for a period of 8 months (February-October) in 1,500 L tanks. Fish representing the three treatment groups were then used for: (1) a stress challenge netting test and plasma cortisol measurement (baseline, peaking, and recovery levels), (2) blood plasma measurements of glucose, triglycerides, lactate, cholesterol, growth hormone (GH), and insulin-like growth factor 1 (IGF1), and (3) heart and muscle gene expression of the GH and IGF1 receptors and the muscle transcriptome by deep RNA sequencing (RNAseq). Fish size after 8 months of flow conditioning was 92 ± 27 g body weight (BW) for fish under minimal flow, 106 ± 24 g BW (+15%) at 1 BL s, and 125 ± 27 g BW (+36%) at 2 BL s. Flow conditioning at 1 BL s provided optimal conditions for growth and uniformity, but also stress (lowest baseline plasma cortisol), robustness (higher condition factor and larger hearts), and energy mobilization (increased plasma glucose). Although flow enhanced growth linearly with swimming speed, also the percentage of lordotic fish increased with exercise, particularly high for swimming at 2 BL s. The absence of important differences in plasma GH and IGF1, and expression levels of their receptors in heart and white skeletal muscle, indicated that other factors may be involved in growth enhancement. RNAseq of the white skeletal muscle showed upregulated expression of genes involved in muscle contraction, muscle development and its molecular regulation, and immune genes that may play a role in the muscle repair mechanism. An exercise regime of swimming at 1 BL s can be considered as optimal for farming robust seabream although the increase of skeletal deformities should be avoided.
在将金头鲷转移至海水网箱之前，延长其陆地养殖期，养殖者将能够受益于因增加水槽水流而带来的运动增强型生长、恢复力和强健度。在本研究中，通过将大量实验鱼置于最小水流条件下，或置于能使其在1或2体长/秒的速度下进行游泳运动的水流条件下，在1500升的水槽中养殖8个月（2月至10月），研究了水流调节的生理效应。然后，将代表三个处理组的鱼用于：（1）应激挑战围网测试和血浆皮质醇测量（基线、峰值和恢复水平），（2）血浆葡萄糖、甘油三酯、乳酸、胆固醇、生长激素（GH）和胰岛素样生长因子1（IGF1）的测量，以及（3）通过深度RNA测序（RNAseq）检测心脏和肌肉中GH和IGF1受体的基因表达以及肌肉转录组。经过8个月的水流调节后，最小水流条件下的鱼体重为92±27克，1体长/秒水流条件下的鱼体重为106±24克（增加15%），2体长/秒水流条件下的鱼体重为125±27克（增加36%）。1体长/秒的水流调节为生长和均匀度提供了最佳条件，但同时也带来了应激（最低的基线血浆皮质醇）、强健度（更高的肥满度和更大的心脏）以及能量动员（血浆葡萄糖增加）。尽管水流随游泳速度线性增强生长，但脊柱前凸鱼的百分比也随运动量增加，在2体长/秒游泳时尤其高。血浆GH和IGF1及其在心脏和白色骨骼肌中受体的表达水平没有显著差异，这表明可能有其他因素参与了生长增强。白色骨骼肌的RNAseq显示，参与肌肉收缩、肌肉发育及其分子调控的基因以及可能在肌肉修复机制中发挥作用的免疫基因表达上调。尽管应避免骨骼畸形增加，但1体长/秒的游泳运动模式可被视为养殖强健鲷鱼的最佳模式。
