帮我改写这段话铁是体内多种酶类和血红蛋白的构成成分铁缺乏或过量都会引起免疫系统的损伤。在细菌或病毒感染初期血清铁含虽下降而当畜禽恢复健康时血清铁含量迅速回升。

Iron is a vital component of various enzymes and hemoglobin in the body, and both iron deficiency and excess can cause damage to the immune system. During the early stages of bacterial or viral infections, the serum iron level decreases, but it rapidly recovers when livestock or poultry regain their health.