日粮中添加L—NAME对肉鸡腹水综合征发生的影响及其机理

应用低温环境和日粮中添加三碘甲腺原氨酸（3，3，5－triiodothyronine,T3)诱发肉鸡腹水综合征，同时通过日粮添加一氧化氮合酶抑制剂L－NAME，研究了抑制NO的合成对肉鸡肺动脉压及肉鸡腹水综合征发生的影响。180羽AA肉鸡随机等分为对照组（C）、试验组（A、B），参试鸡14日前按常规条件饲养。14日龄后C组鸡按常规条件饲养，A、B组鸡舍温按每日1－2℃逐步降至12℃，同时日粮中添加T3 1．5mg/kg以诱发腹水综合征。另外，B组肉鸡从14日龄起在日粮中添加100mg/kgL－NAME至试验结束。分别于3、4、5、6周龄测定各组肉鸡肺动脉平均压（mean pulmonary arterial pressure,mPAP)、红细胞压积、右心全心比、血浆一氧化氮（NO）和内皮素（endothelin-1,ET-1)水平并记录腹水综合征发病率。结果显示：低温添加T3处理后，A、B组肉鸡腹水综合征发病率增加，但B组高于A组；A、B组肉鸡mPAP从5周龄起高于C组（P＜0．05）；A、B组右心全心比的升高分别在6、5周龄时出现，B组右心全心比的升高比A组提前1周；B组 肉鸡血浆NO水平低于A组，差异不显著；A、B组肉鸡血浆ET－1水平高于C组（P＜0．05）；在6周龄时，A组肉鸡心率明显降低，B组肉鸡心率明显升高。随着肺动脉高压和右心肥大的出现，心率的升高可能促进了右心衰竭和肉鸡腹水综合征的发生。上述结果提示，抑制NO的合成可能促进了肉鸡肺动脉高压，右心肥大的形成和肉鸡腹水综合征的发生。

Effect of L-NAME on Pulmonary Arterial Pressure and Ascites Morbidity in Broilers

In this paper pulmonary hypertension syndrome was induced by low temperature environment and 1.5 mg/kg 3,3,5-triiodothyronine(T 3) supplemented dietary,and effect of nitric oxide synthetic inhibitor(L-NAME) on pulmonary arterial pressure and ascites morbidity in broilers was studied.AA broilers 180 were evenly divided into three groups,group C was designed as control group,A?B were treated with low temperature and T 3 supplemented diet,100 mg/kg L-NAME was additionally added to B.It was found that ascites morbidity of A was higher than C but lower than B;Plasma ET-1 of A?B was higher than C(P<0.05),plasma NO of B was lower than A but no significant difference,RV/TV and mPAP of A?B were higher than C(P<0.05) but in B the ratio of RV/TV increased one week early than A,at the sixth week heart rate of broilers in group A had decreased but increased in group B.It was suggested that the down-regulation of NO probably was involved in the increase of pulmonary hypertension and ascites morbidity,and the increase of heart rate due to L-NAME treatment maybe involved the increase of ascites morbidity after the formation of pulmonary hypertension and right ventricular hypertrophy.