维生素D3的来源与功能及动物维生素D缺乏症

Vitamin D3 Source and Function and Animal Vitamin D Deficiency

维生素D_(3)通常被认为是一种“阳光维生素”,这是由于大多数动物在紫外线照射下都能合成,即维生素D_(3)是动物体内必备的维生素,具备显著脂溶性。现阶段,我国养殖动物表现出一定集约化的发展趋势,选取封闭饲养的方法减少动物被阳光照射的时间,不能得到促进自身健康生长的维生素D_(3)含量。长时间之后,动物体内会产生维生素D_(3)的情况,阻碍机体对钙元素以及磷元素的充分吸收,降低动物免疫能力、繁殖水平和生产性能等。在维生素D_(3)含量比较多时,引出动物新陈代谢的过程受到阻碍,降低体内代谢的速度,甚至对动物生存带来伤害。具体表现上,缺乏维生素D_(3)的典型症状是软骨病或佝偻病,D_(3)前体缺乏(7-脱氢胆固醇缺乏),可减少D_(3)、25-OHD_(3)合成,进而产生维生素D缺乏症,高产奶牛因缺钙产后瘫痪;小鸡骨结构变形;猪和马身上出现的骨软骨症生长过快;体重过大的鸡和火鸡中,可看到骨矿化缺乏,称之为胫骨软骨发育不良。

Vitamin D_(3) is often considered to be a“sunshine vitamin”,which is because most animals can be synthesized under ultraviolet irradiation,that is,vitamin D_(3) is an essential vitamin in the animal body,with significant fat solubility.At the present stage,animal breeding in China shows a certain trend of intensive development.The closed feeding method is selected to reduce the time of animals being exposed to sunlight,and the vitamin D_(3) content can not be obtained to promote their healthy growth.After a long time,the production of vitamin D_(3) in the animal body prevents the body from fully absorbing calcium and phosphorus,and reduces the animal's immune ability,reproductive level and production performance.When the content of vitamin D_(3) is relatively high,the process of animal metabolism is hindered,reducing the speed of metabolism in the body,and even causing harm to animal survival.Specific manifestations,the typical symptoms of vitamin D_(3) deficiency are chondrosis or rickets,D_(3) precursor deficiency(7-dehydrocholesterol deficiency),can reduce D_(3),25-OHD_(3) synthesis,and then produce vitamin D deficiency,high-yield cows due to calcium deficiency postpartum paralysis,Chicken bone structure deformation,Osteochondrosis in pigs and horses grows too rapidly,A lack of bone mineralization,known as tibial chondrodysplasia,can be seen in overweight chickens and turkeys.