L-肉碱对低温诱导的肉鸡腹水综合征发病率的影响

The effect of L-carnitine on morbidity of ascities syndrome induced by low temperature in broilers

24 0羽艾维茵 2 0 0 0商品代肉鸡随机等分成常温对照组 (NT)、低温组 (LT)和低温加L肉碱组 (LL)。自 14日龄起 ,LT和LL组舍内温度从 2 8℃以每天 1～ 2℃下降至 2 1日龄时的 14～ 12℃ ,并维持到试验结束 ;NT组在常温下饲养(2 1日龄起舍温控制在 2 0℃ )。自 14日龄起在LL组饲料中添加L肉碱 2 0 0mg·kg-1。记录肉鸡腹水综合征 (ascitessyn drome ,AS)发病率 ,并分别于 2 4、 32、 39和 4 5日龄从各组中随机挑取 10羽 ,测定右心室全心室比 (RV/TV)、右心室相对重量 (RV/BW )、全心室相对重量 (TV/BW )、红细胞压积 (PCV)、血红蛋白 (Hb)、血浆丙二醛 (MDA)含量和超氧化物歧化酶 (SOD)活性。结果发现 :LT组肉鸡AS发病率比NT组高 ;在 2 4和 32日龄时 ,LL组肉鸡左心室重量较NT组增加 ,RV/TV值下降 (P <0 0 1) ,但在 39和 4 5日龄时RV/TV升高 (P <0 0 1) ;LL组PCV值较NT组高 (P <0 0 5 ) ,并高于LT组 ;LL组AS发病率较LT组低 ,且其血浆MDA水平在 39日龄显著降低 (P <0 0 5 ) ,SOD水平在 32日龄时极显著升高 (P <0 0 1) ;L肉碱对肉鸡体重没有明显影响。结果表明 ,L肉碱具有防治AS的作用。

Two hundred and forty Avian-2000 broilers were divided equally into normal temperature control group(NT),low temperature group(LT)and low temperature L-carnitine group(LL).Birds in group LT and LL were subjected to the same low temperatures by lowing 12 ℃ per day from 28 ℃(day 14)down to 1412 ℃(day 21),and remained constant until the end of the experiment,while birds in NT group were reared in normal temperatures.All the birds received pelleted diets whereas group LL received the same diets supplemented with 200 mg·kg -1 L-carnitine from day 14 to day 49. Ascities syndrome(AS)morbidity in each group was recorded daily.Values of right ventricle to total ventricle(RV/TV),right ventricle to body weight(RV/BW),total ventricle to body weight(TV/BW),packed cell volume(PCV),hemoglobin(Hb),plasma superoxide dismutase(SOD)and malondialdehyde(MDA)were determined at 24,32,39 and 45 day of age,respectively.It was found that birds exposed to cold had higher AS morbidity.however,it was reduced by dietary L-carnitine supplementation.Left ventricle weights were increased and RV/TV ratios decreased in birds fed L-carnitine before day 32 when compared to those of controls; however,starting on day 39,RV/TV ratios were dramatically elevated.Birds in LL group had higher PCV values than those of group NT and LT.L-carnitine supplementation reduced plasma MDA concentration on day 39 and increased plasma SOD activity on day 32 in broilers exposed to cold.There were no pronounced differences of BW between birds of group LL and LT.It demonstrated that L-carnitine reduced AS morbidity induced by cold exposure,which might be associated with improving cardiac function and scavenging free radical.