Effects Of Swimming Training On The Flesh Quality And Metabolism Of Thyroid Hormones In Carassius Auratus Gibelio Var.CAS ?

Swimming is one of the main life activities of fish,which is of great significance for its foraging,migration,escaping from enemy enemy and growth.Swimming training will have an impact on fish growth performance,flesh quality,survival rate et al.Therefore,this study of the effect of swimming training on fish physiological activities is helpful to provide basic data for flowing water culture model.Therefore,this study investigated the effects of different water velocities on the regulation of muscle growth and development as well as thyroid hormone metabolism of Carassius auratus gibelio var.CAS ?.We set four water velocity experimental groups,which were 0 bl/s control group and 0.5 bl/s,1 bl/s,2 bl/s training groups.After 8 weeks of training,the indexes of muscle texture,the content of nutritional components?moisture,crude fat,crude protein,ash?,the content of muscle amino acid,the activity of muscle antioxidant enzyme,the expression level of genes related to the regulation of muscle growth and development,serum cortisol content,serum thyroid hormone content,the activity of thyroid hormone deiodinase in liver and the expression of genes related to the regulation of thyroid hormone metabolism were analyzed.The results showed that the hardness,elasticity,cohesion,adhesion and resilience of muscle increased with water velocity.The ash and crude fat content of muscle in 1 bl/s and 2 bl/s training groups were significantly higher than that in 0 bl/s control group?P<0.05?.However,there was no significant difference in moisture and crude protein content between the control group and the swimming training groups.The total antioxidant capacity,glutathione and hydrogen peroxide activity of red muscle and white muscle increased significantly in training groups?P<0.05?.The catalase activity decreased significantly in 2 bl/s training group in white muscle but significantly increased in 1 bl/s swimming training group of red muscle.In red and white muscle,the glutathione peroxidase activity has no significant difference among all groups.The content of superoxide dismutase decreased significantly in white muscle 2 bl/s swimming training group and increased significantly in red muscle 0.5 bl/s swimming training group?P<0.05?.There was no significant difference in malondialdehyde content among the white muscle groups,but significant decreasing in the red muscle 0.5 bl/s swimming training group.The content of lysine in the white muscle increased in the training group.In addition,the level of fresh amino acids in the red muscle increased by swimming training.The swimming training for 8 weeks promoted the expression of muscle regulator genes in white muscle?myod?myf-5?mrf4?and red muscle?myog?myod?mrf4?.On the other hand,there was no significant difference in serum cortisol content among the experimental groups,while the levels of serum T₄ and T₃ increased in the training group,especially in 0.5 bl/s training group?P<0.05?.The content of FT₄ was significantly higher in 2 bl/s swimming training group than other three groups?P<0.05?,and there was no significant difference in FT₃ content between the control group and swimming training groups.In addition,the activity of ID1 in liver increased gradually in0.5 bl/s swimming training group.The activity of ID2 has no significant difference among four experimental groups.The activity of ID3 decreased significantly with the increasement of water velocity.Swimming training significantly increased the gene expression of thyroid hormone receptor?tr-??in liver?P<0.05?.In conclusion,the results showed that swimming training at moderate water velocity could improve the muscle texture characteristics,improve flesh quality,improve the antioxidant capacity of muscle and the expression of myogenic regulator factors?MRFs?,and regulate the level of thyroid hormone metabolism of C.gibelio..