常chang乳ru所suo含han抗kang體ti濃nong度du雖sui然ran遠yuan低di於yu初chu乳ru
，但dan仍reng含han有you一yi定ding抗kang體ti，這zhe些xie抗kang體ti多duo數shu是shi乳ru腺xian淋lin巴ba細xi胞bao合he成cheng的de局ju部bu抗kang體ti，不bu被bei腸chang吸xi收shou，可ke附fu在zai腸chang黏nian膜mo上shang防fang細xi菌jun從cong腸chang入ru侵qin，起qi局ju部bu免mian疫yi防fang病bing作zuo用yong。此稱常乳的乳汁免疫。斷奶後出現拉稀，原因雖多樣，但失去乳汁免疫保護也是一重要原因。

從初乳中移行到仔豬血中的母源抗體，以一定速度減少，一般於生後2周-3zhoushiqubaohu，ercishizaizhulinbaxibaozhudongmianyichanshengdekangtishangshao，nongdudi，bunengchanshengjianqiangbaohu，zheyangzaimuyuankangtidebeidongmianyihezaizhuzhudongmianyijiaojiezhiji，bichuxianmianyibaohudekongdang
，cishizizhukangganrannenglishifencuiruo，shishifenweixiandeshiqi。ciqichangduanyuchichuruduoshaochengzhengxiangguan
，churuchideduozeciqiduan。weishizizhushunliduguociqi，rangzaizhuchizuchurushizuihaobanfa。