中文摘要：

【目的】观察在低温环境下间歇光照对肉鸡肺动脉高压综合征PHS的防治效果及其对肉鸡肺血管重构的影响；【方法】320羽肉鸡随机分为4组：常温对照组（Nc）常规控温，24h连续光照；低温对照组（LC）、低温间歇光照1组和低温间歇光照2组采用低温诱发PHS，并从9d起分别实施24L：0D的连续光照和21L：3D、19L：5D的间歇光照（IL）制度，30d后都为连续光照。记录PHS发病数、体重和耗料量，并分别于14、23、30、37和44d从各组随机抽取l0羽肉鸡采血和扑杀，测定肺动脉的管壁面积与管总面积之比（WMTA）、平均中膜厚度（mMTPA）等指标；【结果】环境低温使PHS发病率升高，反映血管重构指标的WA／TA和mMTPA值也显著升高，而间歇光照能够有效地降低寒冷诱发的PHS发病率和上述各项值。限制光照期间IL组肉鸡体重低于LC组，但最终体重和料重比与LC组间差异不显著；【结论】在肉鸡生长早期实施悯歇光照制度能够有效降低低温诱发的PHS发病率，抑制肺小动脉重构可能是其重要机理之一。

英文摘要：

[Objective] The purpose of the present study was to examine the efficacy of imposing intermittent lighting schedules on reduction of the incidence of ascites（or Pulmonary Hypertension Syndrome,PHS）induced by cool ambient temperature and to investigate its effect on the pulmonary vascular remodeling of broiler chickens. [Method] A total of three hundred and twenty broilers were randomly allocated to four groups. In one group, the continuous lighting schedule （CL）of 24 h light（L）： 0 h dark （D） was maintained, ambient temperature kept normal （normal control group, NC） while in other three groups, the chickens were subjected to cool ambient temperature to induce PHS. The continuous lighting schedule of 24L：0 D （Low temperature control group,LC） and the intermittent lighting （IL） schedule of 21L：3 D（group L1） and 19 L：SD （group L2） were imposed, respectively, from 9 to 30 days of age （From day 30 onwards all groups were kept in continuous lighting）. PHS incidence, body weights and feed intake were measured weekly for each group. Heart, Lung and blood samples were taken from l0 randomly selected birds per group at 14, 23, 30, 37 and 44 days of age, for the determination of the ratio of vessel wall area to total area （WA/TA）, mean medial thickness in pulmonary arterioles （mMTPA）,etc. [Result] The results indicated that the cool ambient temperature could increase morbidity of PHS in broilers, the values of WA/TA and mMTPA also were increased significantly, whereas the intermittent lighting （IL） schedule could successfully decrease the morbidity of PHS induced by cool ambient temperature and the values of WA/TA and mMTPA, which served as describing pulmonary vessel remodeling （P 〈 0.05）. Birds in IL groups were lighter than that in LC group during light restriction period, but both the final body weights and total feed conversion ratio were not significantly affected by the lighting program in all birds subjected to low temperature. [Conclusion ] It is conc