半胱胺对奶牛产奶量及血浆生长抑素、生长激素水平的影响

Effects of Cysteamine on the Milk Yield and Plasma Levels of Somatostatin and Growth Hormone in Dairy Cow

选用１０ 头处于泌乳中期的荷斯坦牛进行自身对照试验。对照期饲喂基础日粮，试验期在基础日粮中添加半胱胺。每隔５ 天一次，剂量为１００ｍｇ／ｋｇ 体重，共喂３ 次。结果表明，试验期奶牛日产奶量比对照期提高７ ．６ ％ （ 对照期１４ ．５ ±３ ．９ｋｇ／ 头，试验期１５ ．６ ±４ ．３ｋｇ／ 头Ｐ＜ ０ ．０５） ；奶牛采食量无明显变化，试验期饲料转化率比对照期明显提高（ 对照期０ ．３２ ±０ ．０１ ，试验期０ ．３０ ±０ ．０２ ，Ｐ＜ ０ ．０１） ；与对照期相比，试验期奶牛血浆生长抑素（ＳＳ） 水平明显下降（ 对照期１ ．２１ ±０ ．３４ｎｇ／ｍｌ，试验期０ ．１４ ±０ ．０５ｎｇ／ｍｌ，Ｐ（ ＜ ０ ．０１） ，生长激素含量显著提高（ 对照期１ ．３３ ±０ ．２６ｎｇ／ｍｌ，试验期１ ．７７ ±０ ．２９ｎｇ／ｍｌ，Ｐ＜ ０ ．０５） ；半胱胺对牛乳脂率无明显影响（ 对照期２ ．１６ ±０ ．５８ ，试验期２ ．５３ ±０ ．０６） 。以上结果表明，半胱胺能明显提高奶牛产奶量，而抑制体内生长抑素，提高内源性生长激素水平，可能为其主要的作用机制。

Holstein cows in mid-lactation were allocated to investigate the effects of cysteamine(CS) on the milk yield and the plasma levels of somatostatin and growth hormone with a self-control design.CS was added once every five days for three times(100mg/kg B W) during experimental period.In comparison with the control ,the averge daily milk yield in the experimental period increased by 7.6%(P<0.05).The food intake did not increased and the feed efficiency was increased markedly.Meanwhile,CS reduced the level of plasma somatostationn (CS) by 88.4%(P<0.05)and increased the level of growth hormone (GH) by 33.1% .However,the fat content of milk remained unchanged.The results indicated that CS might enhance the milk yield in dairy cow during the lactation without changing the milk quality.Inhibiting SS and increasing GH concentration might be involved in main mechanism of CS action.