摘要
本研究由两个实验组成,分别观察了不同钙、锌日粮水平下,肝脏和肾脏细胞浆内金属硫蛋白(MT)含量的动态变化.实验1,在含锌30.2～30.8ppm的大豆—玉米型基础日粮中,分别添加0.72%、3.0%和6.0%的钙,其中3%钙组在实验第220d后,在日粮中添加40ppm锌,继续饲喂9d.实验2,在基础日粮中分别添加1000ppm、2OO0ppm、4O00ppm和4000ppm锌,饲喂13d,其后,第4组(日粮中添加4000ppm锌组)改喂基础日粮.结果如下:实验1,各组肝脏和肾脏锌含量均显著低于实验前的水平,其中6%钙组尤为明显;各组肝、肾细胞浆中MT含量均<0.6ppm,且与其组织锌含量呈正相关;3%钙组添加40ppm锌后,肝、肾锌及MT含量迅速增加,明显高于添加前的水平.由此表明,高钙日粮干扰了肝、肾锌的代谢和MT的合成.实验2,肝、肾锌及MT含量与锌的添加水平及接触锌的时间长短有关,锌含量与MT的变动呈正相关,且MT的增高幅度显著大于锌;切断外加锌源后,肝、肾锌及其MT含量迅速减少,其衰减期分别为9(5～10)和6(5～7)d;MT含量的变动与其他含锌蛋白亦有一定关联.实验2表明,肝脏是合成及贮存NT的主要器官,其效能强于肾脏,MT含量能准确反映体内锌状态.
Two experiments were conducted in order to observe the effects of dietary calcium and zinc on the metallothioneine (MT) contents in liver and kindeys in layers. In the 1st experiment, 150 30-day-old healthy Rose chickens were randomly allotted to 3 groups (Ⅰ-1, Ⅰ-2, Ⅰ-3). All these chickens were fed with the basal feed containing 30 ppm of zinc in the form of zinc sulfate and supplemented with 0.72%, 3.0% and 6.0% calcium (calcium carbonate) for groups Ⅰ-1, Ⅰ-2, and Ⅰ-3 respectively. 220 days later, the feed for I-2 were supplemented with 40 ppm of zinc and fed further for 9 days. In the 2nd experiments, 40 layers were allotted to 4 groups (Ⅱ-l,Ⅱ-2, Ⅱ-3, Ⅱ-4) and fed with 1000, 2000, 4000 and 4000 ppm Zn-supplement-ed basal feed for 13 days respectively. And group Ⅱ-4 was fed with the basal feed later on. It was shown that MT contents in both liver and kidneys correlated positively with the Zn concentrations in those tissues (r=0. 79 and 0. 83) when the layers were fed the feed with low (30 ppm), normal (70 ppm) and high (>1000 ppm) levels of zinc. It was thus suggested that MT contents in liver and kidneys could reflect the zinc status in layers' tissues. Liver MT content was closely correlated with other zinc-conjugated proteins. Under normal condition, the most part of zinc combined with MT, and the ratio of MT to other proteins was>1. 0. When the zinc was deficient, MT would be reduced, and other proteins were not changed or slightly reduced. If the zinc supplement was superhigh (>1000 ppm) , the MT was increased significantly and accompanied with the elevated ratio of MT to other proteins. The effect of dietary zinc on MT in kindeys was less apparent than that in liver. The results showed that MT must be an essential factor for the zinc metabolism in liver. The half-life of MT appeared to be 9 (5-10) days in liver and 6 (4-7) days in kidneys.
关键词
金属硫蛋白
钙
锌
鸡
肝脏
肾脏
metallothioneine
calcium
zinc
layer
liver
kidneys
