甜菜碱在肉鸡体内供甲基代谢及其节约蛋氨酸效应机制

选用 4 5 0羽 2 2日龄艾维茵肉鸡 ,按饲养试验要求分成 3组 (每组 3个重复 ) ,分别设为不添加蛋氨酸的对照组和添加 10 0 0mg/kg蛋氨酸的对照组 ,另一组则为添加 5 0 0mg/kg甜菜碱的试验组 ,进行了为期 2 1d的饲养试验。结果表明 :与不添加蛋氨酸组比 ,添加甜菜碱显著提高了肉鸡的日增重 (P <0 .0 5 ) ,降低了料重比(P <0 .0 5 ) ,达到了添加蛋氨酸的效果 (P >0 .0 5 ) ;添加甜菜碱导致了试验鸡肝脏甜菜碱 -高半胱氨酸S -甲基转移酶 (BHMT)活性升高 ,BHMT活性比不添加蛋氨酸组和添加蛋氨酸组均显著增高 (P <0 .0 1) ;与不添加蛋氨酸组比 ,添加甜菜碱还使肝脏甲基化反应产物 (游离肉碱和肌酸 )的生成量明显增多 (P <0 .0 1)和胸肌中两者的存储量显著增加 (P <0 .0 1) ,但与添加蛋氨酸组比无明显差异 (P >0 .0 5 )。上述结果提示 :甜菜碱在肝脏BHMT调控下 ,替代蛋氨酸为机体甲基化产物的合成提供甲基 ,从而产生节约蛋氨酸的效应。

Study on Methyl Metabolism of Betaine in Broilers and the Consequentia Methionine Sparing

Three groups,of broiler,150 each,were fed with a same basal diet,supplemented separately with 0 (control group),1000 mg/kg methionine (M group), or 500mg/kg betaine for 21 days from age of 22d to 49d. In the betaine group the average daily gain of broilers increased(P<0.05)and feed gain ratio decreased (P<0.05) compared with the control group and no significent difference compared with M group(P>0.05). The betaine-homocysteine s-methyltransferase (BHMT) activity in the liver increased with the betaine supplementation(P<0.01)compared with the control group or M group. The free carnitine and creatine concentrations in the liver or muscle of the betaine-treated broilers were higher than those of the control group but, did not differ from those of the M group. The methionine sparing effects of betaine may suggeste that with activity of BHMT betaine instead of methionine provides methyl for the synthesis of methylation products.