甜菜碱对生长肥育猪体脂重分配的作用及机理研究

通过48头20～65　kg生长猪和60头60～95　kg肥育猪（Duroc×Landrace×Yorkshire）饲养、屠宰试验和有关生化指标分析，探讨了甜菜碱对生长肥育猪皮下脂肪沉积、胴体脂肪率和肌内脂肪含量的影响及其作用机理。48头生长猪和60头肥育猪分别分成对照和试验2个处理组，每个处理含3个重复，生长猪和肥育猪的试验组分别饲喂含1000　mg／kg和1500　mg／kg甜菜碱的饲粮。结果表明添加甜菜碱，提高了生长猪的日增重13.20％（P＜0.05），降低了料重比7.93％（P＜0.05）；分别降低生长猪和肥育猪的背膘厚14.82％（P＜0.05）和14.93％（P＜0.05）、脂肪率5.76％（P＞0.05）和11.51％（P＜0.05）；分别提高背最长肌肌内粗脂肪含量36.00％（P＜0.05）和17.66％（P＜0.05）。血清生化指标分析表明甜菜碱分别提高生长猪和肥育猪脂肪酶活性10.49％（P＜0.05）和7.50％（P＝0.06），分别提高了血清游离脂肪酸含量20.16％（P＜0.05）和13.43％（P＜0.05），显示甜菜碱加强了猪体脂动员。进一步研究表明，饲喂甜菜碱的生长猪和肥育猪肝脏游离肉碱含量分别提高了20.68％（P＜0.05）和23.53％（P＜0.05），肥育猪背最长肌中酸不溶肉碱含量以及酸不溶肉碱和游离肉碱比例分别提高了48.59％（P＜0.01）和38.24％（P＜0.01），结果揭示甜菜碱似通过提供肉碱合成所必需的甲基以提高生长肥育猪肝脏游离肉碱的含量，促进长链脂肪酸进入肌肉线粒体进行β-氧化，在减少体脂（主要是皮下脂肪）同时，适度增加肌肉脂肪含量，从而发挥着重新分配体脂的作用。

EFFECT OF BETAINE ON REPARTITION OF CARCASS FAT IN GROWING AND FINISHING PIGS AND APPROACH TO IT’S MECHANISM

Two trials were conducted to investigate the effect of feeding betaine on the deposition of subcutaneous fat，carcass fat and the contents of intramusclar fat of the growing and finishing pigs and approach to mechanism of the effect by feeding experiment，determination of carcass，and liver，muscle and serum sample analysis．Trial 1 examined the effect of betaine supplementation （1000 mg／kg of diet） to the growing pigs．Forty-eight pigs（Duroc×Landrace×Yorkshire，20 kg initially） were allotted to two treatments set with three replicate pens per treatments by weight and sex．Trial 2 examined the effect of feeding betaine （1500 mg／kg of diet） to the finishing pigs．Sixty pigs （Duroc×Landrace×Yorkshire，60 kg initially） were allotted to two treatments set with three replicate pens per treatments by weight and sex．The results showed that betaine supplementation increased the ADG of growing pigs by 13．20％（P＜0．05），decreased the FCR by 7．93％（P＜0．05），decreased the mean backfat depth of the growing and finishing pigs by 14.82％（P＜0．05） and 14．93％（P＜0．05），decreased the percentage of dissected fat of carcass by 5．76％（P＞0．05） and 11．51％（P＜0．05），increased the contents of intramusclar fat in longissimus dorsi（LD） of the growing and finishing pigs by 36．00％（P＜0．01） and 17．66％（P＜0．05） respectively．The serum analysis indicated that betaine supplementation increased the lipase activity of the growing pig and finishing pigs by 10．49％（P＜0．05） and 7.50％（P＝0.06），increased the FFA contents of growing and finishing pigs by 20．16％（P＜0．05） and 13.43％（P＜0．05） respectively．In addition，the contents of free carnitine in liver of the growing and finishing pigs fed betaine increased by 20．68％（P＜0．05） and 23．53％（P＜0．05） respectively．The contents of acid-insoluble carnitine，the ratio of acid-insoluble carnitine and free carnitine in LD of finishing pigs fed betaine increased by 48．59％（P＜0．05） and 38．24％（P＜0．01） respectively．These results indicated that betaine supplementation could reduce the lipid deposition and exert the repartition effects of the carcass fat throughout donate the methyl to produce carnitine to improve the long chain fatty acid-β-oxidation．