Effects Of Dietary Carotenoid On Nutrition And Physiology Of Haliotis Gigantea With Orange Muscle

Haliotis gigantea is one of the important economic abalone species along the coast of Japan and South Korea.It has high-temperature adaptability,disease resistance and breeding potential.The foot muscle of most H.gigantea is pale yellow,but a small proportion of individuals have bright orange-red foot muscle.Comparatively,the latter group does appear not only beautiful in color but also rich in carotenoids.The content of carotenoids in H.gigantea is the highest in shellfish reported so far.It is a rare and excellent material for studying the mechanism by which carotenoids are utilized in animals and selecting traits of abalone.In this paper,the effects of heredity and diet on the orange muscle traits of H.gigantea were studied by combining the pedigree genetic analysis and bait experiment.The effects of dietary carotenoids on muscle color,total carotenoid content(TCC),growth,survival,nutritional composition,high temperature and pathogen tolerance of H.gigantea were investigated by adding different kinds and concentrations of carotenoids into formula feed.The specific outcomes are as follows:1.There were significant differences in physiological and biochemical indexes between the common and orange-muscle mutants of H.gigantea.Compared with the common ones,the orange-muscle mutants showed bright color,high carotenoid content,strong resistance to bacteria,weak resistance to high temperature and a high overall survival rate in culture.However,there were no significant differences in growth rate,hydrolyzed amino acids,fatty acids and glycogen contents.2.Genetic factors play a decisive role in the color of the foot muscles of H.gigantea.The orange muscle character of H.gigantea was recessive to the common character.The orange muscle character and carotenoid content could be inherited stably and improved and stabilized by selection.3.The color of the foot muscle of H.gigantea is regulated by genetic factors and greatly affected by the diet.Adding a certain amount of carotenoids in the formula feed could promote the color of the foot muscle of H.gigantea to become red,but the effect was not as good as when Gracilaria lemaneiformis with the exact content of carotenoids was used.At present,G.lemaneiformis was the best bait for improving the color of the foot muscle of H.gigantea.When the carotenoid concentration in H.gigantea reached a certain level,the increase rate of carotenoid could be decreased.After changing bait,an apparent "fading" phenomenon was observed in H.gigantea with high carotenoid content in the body.4.The nutrient composition in the formula feed was more scientific and balanced,and it could promote the growth of abalone more than G.lemaneiformis.The addition of astaxanthin,zeaxanthin or β-carotene in the formula feed had no significant effects on the foot color,TCC in muscle,growth,and survival of H.gigantea.The addition of astaxanthin in the diet could not induce the accumulation of astaxanthin in H.gigantea.5.The addition of carotenoids in the formula feed can significantly affect the nutrient composition in the foot muscle of H.gigantea.Adding 40 mg/kg astaxanthin in the formula feed could significantly increase the content of flavoring amino acids in the foot muscle of H.gigantea.The content ratio of proline,phenylalanine,isoleucine and C4:0、C10:0、C14:0、C16:0、C17:0、C18:0、C24:0、C14:1、C17:1、C18:ln9t、C24:1、C18:2n6c、C18:2n6t、C18:3n3、C20:40n6、C20:5 in the foot muscle of H.gigantea were significantly affected by carotenoid supplementation in the formula feed.Adding 40 mg/kg β-carotene in the formula feed significantly increased the content of monounsaturated fatty acid(MUFA)in the foot muscle of H.gigantea.Adding 500 mg/kg β-carotene in the formula feed can significantly reduce the glycogen content of common abalone.6.The addition of carotenoids in the formula feed can significantly improve the ability to cope with acute pathogen stress and significantly improve the hightemperature tolerance of H.gigantea.Adding 10-500 mg/kg astaxanthin in the formula feed could increase the total antioxidant capacity and reduce the concentration of malondialdehyde(MDA),which could help abalone cope with acute pathogen stress or ROS damage.Astaxanthin(10-500 mg/kg)or zeaxanthin(40-140 mg/kg)can improve the attachment duration of H.gigantea at 32℃,which implies abalone can cope with higher water temperature.