甜菜碱对肉雏鸡蛋氨酸和脂肪代谢的影响

EFFECTS OF BETAINE ON METHIONINE AND ADIPOSE METABOLISM IN BROILER CHICKS

用添加６００、１３００、２０００、２７００ｍｇ／ｋｇ甜菜碱的饲粮，以添加和不添加蛋氨酸为对照，分别饲喂艾维茵雏鸡２４ｄ（１～２４日龄），均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，其中以２０００ｍｇ／ｋｇ剂量组效果最为明显，ＢＨＭＴ活性比不添加蛋氨酸组高８１．２５％（Ｐ＜０．０１），较添加蛋氨酸组高１０３．００％（Ｐ＜０．０１）；低剂量（６００ｍｇ／ｋｇ）组还降低了肝脏胱硫醚β－合成酶（β－ＣＹＳＴ）的活性，比不添加蛋氨酸组低１７．６５％（Ｐ＜０．０２），较添加蛋氨酸组低２２．２２％（Ｐ＜０．０１）；此外，与不添加蛋氨酸组比，不同剂量组均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＜０．０２），但与添加蛋氨酸组比无明显差异（Ｐ＞０．０５）。血清和胸肌样品分析结果表明：与不添加蛋氨酸相比，不同水平甜菜碱均使血清游离脂肪酸浓度、胸肌细胞内总酸不溶肉碱（肉碱载长链脂肪酸通过线粒体膜的复合物）含量和总酸不溶肉碱／游离肉碱比率明显升高（Ｐ＜０．０５），但与添加蛋氨酸组比，差异均不显著（Ｐ＞０．０５）。上述结果提示：甜菜碱在肝脏ＢＨＭＴ和β－ＣＹＳＴ的双重调控下，替代蛋氨酸为机?

Eight hundred and ten Avian broiler chicks were allotted to six groups by weight Every group included three replicate lots of fourty five birds each The groups received the same basal diet(3 01 Mcal/kg ME,22 01% CP,0 29%Met,0 51%TSAA)supplemented with 0 (Met unadded control group,MUG),600,1300,2000,2700mg/kg betaine respectively (test groups),or 2000 mg/kg methionine (Met added control group,MAG)during the period of 1 to 24 days posthatching The results indicated that betaine groups obviously increased the betaine homocysteine s methyltransferase(BHMT)activity in the liver Among the levels,2000mg/kg betaine was the most effective,which increased BHMT activity by 81 25% and 103 00%(p<0 01)compared with MUG and MAG respectively Adding 600mg/kg betaine decreased the cystathionine β synthetase specfic activity in the liver by 17 65% and 22 22%(p<0 01)in contrast to MUG and MAG respectively In addition,it was found that free carnitine and creatine concentration in the liver of broiler chicks treated with betaine were higher(P<0 02)than those of MUG,but didnt distinguish from those of MAG(p>0 05). Betaine groups apparently improved the free fatty acid concentration in the serum,total insouble carnitine concentration and ratio of it to free carnitine in the breast(p<0 05)when compared with MUG,yet had no significant difference in contrast to MAG(P>0 05) These results suggested that betaine might exert the functions:(1)sparing methionine by providing effective labile methyl for methylation products synthesis instead of methionine under control of betaine homocysteine s methyltransferase and cystathionine β synthetase;(2)lowing abodominal fat by increasing carnitine synthesis,improving loading and β oxidition of fatty acid and further providing adequate energy(creatine phosphate)for cell imtabolism