肉鸡腹水综合征患鸡右心组织钙沉积和Ca2+-ATPase活性变化

右心肥大衰竭是腹水综合征患鸡发病的重要环节之一,而心肌细胞内Ca^2＋浓度在调节心脏收缩和舒张功能及其生长方面都起着重要作用。本试验应用右心导管法测定AS患鸡右心压力变化情况,采用焦锑酸钾沉淀法、电镜酶细胞化学法研究AS患鸡右心组织Ca^2＋和钙泵（Ca^2＋-ATPase）活性变化及其精确定位。结果显示AS组肉鸡右心室舒张压极显著高于对照组（P〈0.01）,同时,右心室内压最大变化速率也极显著降低（P〈0.01）;对照组肉鸡右心组织偶见少量散在的Ca^2＋沉淀颗粒,低温诱发AS患鸡右心组织发生了明显的钙沉积;对照组肉鸡的右心组织Ca^2＋-ATPase以高电子密度颗粒分布于肌浆网、线粒体膜等处,AS患鸡心脏组织的Ca^2＋-ATPase的电子密度颗粒显著减少或缺失。本研究揭示,在低温条件下AS患鸡具有明显的右心舒张功能障碍,Ca^2＋浓度增高和Ca^2＋-ATPase功能抑制可能在其中起着重要作用。     

肉鸡腹水综合征患鸡右心组织钙含量的研究

利用原子吸收分光光度法和焦锑酸钾组化电镜技术,测定肉鸡右心室壁总钙和右心室组织细胞内游离Ca2+含量和分布。结果显示肉鸡腹水综合征患鸡右心室壁总钙含量为(71.2±6.5)mg/kg,显著高于低温未发病和健康肉鸡(分别为58.0±4.4,46.8±3.1,P<0.01)。电镜观察发现Ca2+沉淀颗粒主要散在分布于患鸡心肌胞浆、肌浆网、线粒体等部位,腹水综合征患鸡Ca2+颗粒的沉积量比健康肉鸡显著增多。结果提示心肌细胞内Ca2+的异常可能与肉鸡腹水综合征的发生发展有关。     

Increased calcium deposits and decreased Ca-ATPase in erythrocytes of ascitic broiler chickens

The decrease of erythrocyte deformability may be one of the predisposing factors for pulmonary hypertension and ascites in broiler chickens. In mammals, the cytoplasmic calcium is a major regulator of erythrocyte deformability. In this study, the erythrocyte deformability was measured, and the precise locations of Ca²⁺ and Ca²⁺-ATPase in the erythrocytes were investigated in chickens with ascites syndrome induced by low ambient temperature. The results showed that ascitic broilers had higher filtration index of erythrocyte compared with control groups, indicating a decrease in erythrocyte deformability in ascitic broilers. The more calcium deposits were observed in the erythrocytes of ascitic broilers compared with those of the age-matched control birds. The Ca²⁺-ATPase reactive grains were significantly decreased on the erythrocyte membranes of ascitic broilers. Our data suggest that accumulation of intracellular calcium and inhibition of Ca²⁺-ATPase might be important factors for the reduced deformability of the erythrocytes of ascitic broilers.     

Echocardiographic characteristics of chickens with ascites syndrome

1. B- and M-mode echocardiography was used to compare cardiac function in broilers with spontaneous ascites syndrome with that of normal chickens. 2. Thirty ascitic chickens and 15 normal chickens aged three, 4, 5, and 6 weeks from the same flock (180 birds in total) were examined. They were restrained gently in a natural standing position, and echocardiographs were obtained from a 7.0-MHz linear transducer placed on the left pectoral apterium. Indices of cardiac structure and functioning were calculated from the echocardiographs, and some were normalised to body weight. Heart rate was also measured. 3. All cardiac structural indices in both ascitic and normal chickens increased with age. Compared with normal chickens, right ventricular diameter at the end of systole in ascitic chickens was greater at 4, 5 and 6 weeks of age. Ventricular septal thickness at the end of both systole and diastole was greater in ascitic chickens at 5 and 6 weeks. Left ventricular free wall thickness at the end of diastole was less in ascitic chickens at 3 weeks. However, all the structural indices decreased with age after normalisation with body weight. 4. The heart rate of ascitic chickens was lower at 4, 5 and 6 weeks. Normalised left ventricular fractional shortening was lower in ascitic chickens at 4, 5 and 6 weeks, as was normalised right ventricular fractional shortening. Incrassation of the ventricular septum (Delta T), which changed little in normal chickens, was less at 4, 5 and 6 weeks in ascitic chickens. Left ventricular fractional shortening, right ventricular fractional shortening and Delta T were all negatively correlated with ascites heart index at all ages. 5. Taken together the results suggest heart failure of both ventricle, but that right ventricular dysfunction is more extensive than left ventricular dysfunction. We suggest that secondary pulmonary hypertension would result in these ascitic chickens due to volume overload.     

维拉帕米对低温诱发腹水综合征肉鸡右心功能的影响

本试验旨在探讨钙离子内流阻滞剂维拉帕米（verapamile）对腹水综合征肉鸡右心功能的影响。结果显示，维拉帕米使低温诱发的肉鸡腹水症发生率以及肉鸡腹水心脏指数降低。与低温对照组相比，维拉帕米组28日龄鸡右心室收缩压显著降低（P〈0．05），36、44日龄鸡右心室收缩压有所降低（P〉0．05），而28和36日龄鸡右心室舒张压显著降低（P〈0．01）。     

卡托普利对腹水综合征肉鸡右心功能的影响

150只15日龄AA肉鸡随机分为常温组、低温组和卡托普利组,探讨卡托普利对腹水综合征肉鸡右心功能的影响。结果:卡托普利降低低温诱发肉鸡腹水的发生率;卡托普利降低低温诱发肉鸡肺动脉高压;卡托普利与低温组比降低肉鸡腹水心脏指数;28、36日龄和44日龄,卡托普利组右心室收缩压低于低温组(P0.05);28、36日龄和44日龄,卡托普利组右心室舒张压分别极低于低温组((P0.01)。本试验证明卡托普利可以降低腹水发生率和右心肥大,有效维护右心功能。     

肉鸡腹水症发病机理研究Ⅳ.肉鸡和蛋仔鸡左右心室功能的比较研究

试验选用快速生长的艾维茵肉鸡和海兰蛋仔鸡 ,各试验组用右心导管法和左心导管法测定肺动脉压(PAP)、右心室收缩压 (RVSP)、左心室收缩压 (LVSP)、左右心室内压最大变化速率 (+dp/dt)的动态变化。并且比较了相同体重健康蛋仔鸡、肉鸡的左右心室功能变化特点。结果表明 :相同日龄肉鸡肺动脉压显著高于蛋仔鸡 ;2 8、35日龄肉鸡右心收缩压显著高于蛋仔鸡 (P <0 0 5) ,2 8、35、42和 49日龄肉鸡左心室收缩压低于蛋仔鸡 ,且差异极显著 (P <0 0 1 )。肉鸡左心室内压最大变化速率 (LV +dp/dt)从 2 1日龄测定起呈现显著性低于同日龄的蛋仔鸡。相同体重的肉鸡和蛋鸡相比 ,肉鸡肺动脉压 (PAP)显著高于蛋仔鸡 ,但肉鸡右心室内压最大变化速率 (RV +dp/dt)、左心室收缩压 (LVSP)、左心室内压最大变化速率 (LV +dp/dt)显著低于蛋仔鸡。这提示肉鸡先天存在着肺动脉压较高、左心室病理性功能低下 ,这可能是肉鸡容易发生腹水症的原因之一     

Pathogenesis of ascites in broilers raised at low altitude: aetiological considerations based on echocardiographic findings

This study reports novel insight into the aetiology of pulmonary hypertension and ascites in broiler chickens. The scope of measurements was focused on anatomical and functional parameters, and blood flow patterns in leghorns (resistant to ascites), fast-growing broilers (susceptible to ascites), broilers developing ascites, and ascitic broilers evaluated in vivo using echocardiography, and further examined in the context of postmortem findings. Both, in vivo observed features and postmortem findings, showed clear differences between broilers and leghorns, and between normal and ascitic broilers. Abnormalities in the heart chamber geometry and blood flow patterns were detected upon echocardiographic examination in all ascitic broilers. Right and left atrio-ventricular (AV) valve regurgitation were common findings in ascitic broilers and some apparently normal broilers, with left AV valve insufficiency being a predominant feature with respect to degree and frequency of occurrence. Blood flow disturbances were not detected in leghorns. Left ventricular fractional shortening (functional parameter) was considerably reduced (P < 0.01) in ascitic birds (mean: 21.7 +/- 2.0 SE) in comparison with normal broilers (mean: 39.1 +/- 3.6 SE), or leghorns (mean: 43.3 +/- 2.4 SE). The presented findings indicate that pathological and functional changes in the left ventricle and atrium play a significant role in the pathogenesis of ascites in broilers. Severe dilation of the left atrium and pulmonary veins seen on postmortem examination, as well as regurgitant blood flow in the left atrium, demonstrated by Doppler study in ascitic birds, provide evidence that chronically elevated pressure in the left atrium is involved in the aetiology of pulmonary hypertension and ascites in fast-growing broilers.     

A study on pathogenesis of sudden death syndrome in broiler chickens

Sudden death syndrome (SDS) in fast growing broiler chickens has been recognized as a patho-physiological entity for four decades, but its pathogenesis still remains unknown. More recent investigations provided evidence that link SDS to cardiac arrhythmia, but the mechanism triggering arrhythmogenesis and factors responsible for fatal outcome are poorly understood. In order to understand the chain of events leading to SDS in broilers, the present study focused on putative mechanisms that trigger arrhythmia and mechanisms that predispose the myocardium to fatal arrhythmia. Susceptibility of broilers to cardiac arrhythmia under stress conditions was evaluated using a simulated stress test with epinephrine. Detailed histopathological evaluation of the broiler heart was undertaken to identify structural features that may predispose the myocardium to fatal arrhythmia. The simulated stress challenge revealed that many broilers are highly susceptible to stress induced cardiac arrhythmia. In some broilers the stress challenge induced severe ventricular arrhythmia, and the life threatening nature of this arrhythmia was evidenced by the fact that several birds showing the most severe arrhythmic responses, died suddenly within several days after the stress challenge. Examination of hearts of broilers that died of SDS revealed microscopic lesions in the cardiomyocytes, and widespread changes in the sub-endocardial and mural His-Purkinje system (HPS). Immune staining for Caspase-3 confirmed that numerous Purkinje cells in the left ventricular myocardium from broiler chickens that died of SDS were undergoing apoptosis. The observed lesions suggest that the electrical stability of the myocardium was compromised. Taken together, our findings indicate that stress is a most likely trigger of cardiac arrhythmia in broilers, whereas the pathological changes seen in the myocardium and in the HPS in fast growing broilers provide a very conducive milieu for sustained ventricular arrhythmia. In cases where the electrical stability of the myocardium is compromised, even an episodic arrhythmic event may readily degenerate to catastrophic ventricular fibrillation and sudden death. We conclude that the combination of stress and changes in the cardiomyocytes and HPS are the key requisite features in the pathogenesis of SDS.     

Ultrastructural and molecular changes in the left and right ventricular myocardium associated with ascites syndrome in broiler chickens raised at low altitude

The present study examines ultrastructural and molecular changes in ventricular myocardium associated with ascites cases in fast-growing broilers raised at low altitude. Extensive ultrastructural lesions were seen in the left and right ventricular myocardium of broilers with fulminant heart failure and ascites. Significant changes included lesions in the myofibril contractile apparatus, altered mitochondria, marked reduction in the myofibril component, and changes in the extracellular matrix (ECM) architecture. No lesions were observed in hearts of slow growing broilers, but mild to moderate changes (predominantly in the left ventriculum) were apparent in the hearts from some clinically normal, fast-growing broilers. SDS-PAGE profiles of washed myofibrils showed several distinctly different bands in preparations from left ventricular myocardium of ascitic birds. Western blot analysis of these samples revealed several fragments of myosin heavy chain, M-protein, and titin. Based on gelatinolytic activity, matrix metalloproteinases (MMP) in the cytosolic fraction of ventricular myocardium homogenates were identified as MMP-2. The relative activity of this enzyme appears to be considerably higher in preparations from broilers, particularly in the preparations from the left ventriculum of fast-growing broilers, in comparison to leghorns or slow growing broilers. The nature and distribution of the changes in the heart indicate that chronic cardiomyopathic process in the left ventricular myocardium occurs during the development of ascites. It is postulated that progressive deterioration of the left heart pump function caused by initial lesions in the left ventricular myocardium is a significant factor in the development of pulmonary hypertension and the pathogenesis of ascites in broilers raised at low altitude.     

Lesions of the pericardium and their significance in the aetiology of heart failure in broiler chickens

The present study focuses on lesions of the pericardium commonly observed in fast growing broilers. These lesions are examined in the context of electrophysiological and functional changes associated with cardiac performance and patho-physiology in broilers succumbing to acute or chronic heart failure. Typical lesions involving the pericardium in fast growing broiler chickens included: (1) excessive pericardial effusion, (2) locally extensive or focal adhesions between parietal and visceral components of the pericardium, (3) fibrous deposits on visceral pericardium, and (4) thickened pericardium. Echocardiographic evidence indicated that severe pericardial effusion and/or adhesions may have a restrictive effect on heart pump function, where both diastolic and systolic function of the heart may be affected. Electrocardiographic data showed a strong trend indicating that pericardial adhesions may be associated with ventricular arrhythmia and increased risk of sudden death in fast growing broilers. Relatively high levels of matrix metalloproteinase MMP-2 activity have been found in pericardial effusions from affected chickens, suggesting a possible involvement of this enzyme in the aetiology of pericardial lesions. The present results indicate that pericardial lesions may be associated with biochemical, morphological, electrophysiological, and functional changes occurring in the hearts of broilers succumbing to acute or chronic heart failure and ascites.     

Comparative assessment of right ventricular performance from the pressure-volume relationship in double-muscled and conventional calves.

Forty-one and 55 records of right-sided and systemic arterial pressures, cardiac output, and end-diastolic and end-systolic right ventricular volumes were collected from a group of 6 conventional and 6 double-muscled calves, respectively. In each group, the mean right ventricular pressure-volume loop was constructed. Global cardiac performance was significantly lower in the double-muscled than in the conventional calves. The right ventricular end-diastolic and end-systolic volumes, as well as the diastolic portion of the mean pressure-volume loop, were similar in the 2 groups. Those results suggest that the reduced cardiac performance of double-muscled calves is not due to a lowered ventricular preload and that diastolic properties of their myocardium are similar to those of conventional calves. When expressed on a body weight basis, however, the right ventricular end-diastolic and end-systolic volumes were lower in the double-muscled than in conventional calves. When expressed as a function of probable metabolic demand, therefore, the volumetric capacity of the cardiac pump appears to be reduced in double-muscled calves. The significantly lower right ventricular ejection fraction, maximal rate of ventricular pressure rise and right ventricular peak-systolic pressure to end-systolic volume ratio measured in double-muscled as compared with conventional calves suggest that reduced myocardial contractility may also be partly responsible for the significantly lower stroke index of the former calves. The cardiac pump of double-muscled cattle thus seems to be less effective than that of conventional cattle because of reduced volumetric capacity and lowered strength of contraction.     

Echocardiographic study of pulmonary hypertension syndrome in broiler chickens

Echocardiography was used to study cardiovascular structure and function during the development of pulmonary hypertension syndrome (PHS) in broiler chickens. Body weight-normalized right and left ventricular diameters at both end-diastole (RVDD, LVDD) and end-systole (RVDS, LVDS) were determined weekly in broilers reared under either normobaric (altitude, 96.7 m) or hypobaric conditions (simulated altitude, 2900 m) until 5 wk of age. Hypobaric-exposed broilers had larger RVDD at 3 and 4 wk of age and larger RVDS at 3, 4, and 5 wk of age. Hypobaric-exposed broilers also had larger LVDD at 2, 3, 4, and 5 wk of age and larger LVDS at 4 wk of age. Right (RVFS) and left ventricular fractional shortening (LVFS) were smaller in hypobaric- vs. normobaric-exposed broilers at 3, 4, and 5 wk of age and at 4 wk of age, respectively. Among hypobaric-exposed birds, PHS-positive (+) broilers had larger RVDD and RVDS than PHS-negative (-) broilers on week 3 and on weeks 1 and 3 after hypobaric exposure, respectively. PHS-positive (+) broilers also had smaller RVFS on week 1 after hypobaric exposure. Electrocardiographic and post-mortem data indicated that PHS+ broilers also developed right ventricular hypertrophy when compared with PHS-negative (-) broilers. These results are consistent with the hypothesis that PHS develops as a result of pulmonary hypertension and cardiac overload and suggest that PHS+ broilers have a greater and more persistent reaction to hypoxia than PHS- broilers.     

Effects of Clostridium butyricum on Calcium and Phosphorus Metabolism and Tibia Indexes of Broilers

The effects of Clostridium butyricum on calcium and phosphorus metabolism and tibia indexes in broiler chickens were evaluated in this study.One hundred eighty 1-day-old healthy Arbor Acres broiler chickens were randomly allotted to three groups:the control group,antibiotic group and Clostridium butyricum group with six replicates per group and 10 chickens per replicate.The broilers in control group were fed with the basic diet,while the antibiotic group was fed with 5 mg/kg of flavomycin,75 mg/kg of aureomycin and 20 mg/kg of kitasamycin.Clostridium butyricum group was fed with 2.5×10⁸ CFU/kg Clostridium butyricum in the basic diet for 42 days.The results showed that:Compared with the control group,①the supplementation of Clostridium butyricum did not significantly affect serum calcium and phosphorus level of broilers (P>0.05),and adding antibiotic significantly increased serum calcium level of 21-day-old broilers(P<0.05).②The addition of Clostridium butyricum increased tibia strength at 21-day-old (P<0.05),and phosphorus content of tibia at 42-day-old (P<0.01).③The supplementation of Clostridium butyricum extremely significantly decreased the phosphorus content in feces of 21-day-old broilers (P<0.01),and had no significant difference with ATB group (P>0.05).The supplementation of Clostridium butyricum increased calcium content (P<0.01) and phosphorus content (P<0.05) in feces of 42-day-old broilers.Based on the above results,adding 2.5×10⁸ CFU/kg Clostridium butyricum could improve the tibia development,increase the absorption and utilization of calcium and phosphorus by broilers,and efficiently reduce the calcium and phosphorus excretion of 21-day-old broilers,but not for 42-day-old broilers.     

丁酸梭菌对肉鸡钙磷代谢和胫骨指标的影响

试验通过在基础日粮中添加丁酸梭菌,研究其对肉鸡钙磷代谢和胫骨指标的影响。选择1日龄180只健康AA肉鸡,随机分入3个处理组,每个处理组6个重复,分别为对照组、抗生素组（ATB）和丁酸梭菌组（CB）。对照组饲喂基础日粮,ATB组在基础日粮中添加5 mg/kg黄霉素、75 mg/kg金霉素和20 mg/kg吉他霉素,CB组在基础日粮中添加2.5×10⁸ CFU/kg丁酸梭菌,试验期42 d。结果显示,与对照组相比,①CB组肉鸡血清钙（Ca）、磷（P）含量差异不显著（P>0.05）,21日龄ATB组肉鸡血清钙含量显著提高（P<0.05）;②21日龄CB组肉鸡胫骨强度显著提高（P<0.05）;42日龄CB组肉鸡胫骨磷含量极显著提高（P<0.01）;③21日龄CB组肉鸡排泄物中磷含量极显著降低（P<0.01）,并与ATB组无显著差异;42日龄CB组肉鸡排泄物中钙含量极显著提高（P<0.01）,排泄物中磷含量显著提高（P<0.05）。综合上述结果,在AA肉鸡基础日粮中添加2.5×10⁸ CFU/kg丁酸梭菌有利于改善肉鸡的胫骨发育,改善肉鸡对钙、磷的吸收利用,能有效降低21日龄肉鸡钙、磷排泄量,但并未降低42日龄肉鸡排泄物中钙、磷含量。     

肉鸡腹水综合征的心电图学研究进展

近年对肉鸡腹水综合征的研究已取得进一步的认识 ,在研究肺动脉高压的同时更注意具有潜在作用的心脏病变的研究。家禽的心脏传导系统比较特殊 ,它含有一个返回分支束 ,使右房室瓣受传导神经的支配。当右房室瓣不受传导神经的支配时 ,瓣膜功能不全而引起右心室容量过大 ,可介导右心室肥大。心电图描记是研究肉鸡腹水综合征发病机理的有效手段之一。文章系统地阐述了肉鸡心脏的形态结构和传导系统的特点以及几种肉鸡腹水综合征试验模型的心电图学特征、肉鸡的心脏病理变化与心电图学特征之间的关系     

Whole blood and plasma viscosity values in normal and ascitic broiler chickens.

1. Whole blood and plasma viscosity values in normal and ascitic broiler chickens were measured. 2. The mean blood viscosity value in ascitic broilers was greater than that of the controls. There was a small but significant difference in the opposite direction between plasma viscosity values of the respective groups of birds. 3. Although the haematocrit and arterial pressure index values in the ascitic birds were raised, there was a fall in the concentration of total plasma protein. 4. The data suggest that the raised viscosity in the ascitic birds was caused by a polycythemia and not by any influence of plasma protein. 5. The cumulative effect of these factors, such as raised blood viscosity values and larger deformed red cells flowing through constricted lung arterioles, may contribute to the pulmonary hypertension and ascites seen in some young commercial broilers.     

不同剂量替米考星对雏鸡心脏功能和呼吸的影响

本试验将70只45日龄的罗曼鸡随机分成对照组和试验Ⅰ~Ⅵ组,旨在探讨不同剂量替米考星对雏鸡心功能和呼吸的影响。结果显示,随着替米考星剂量的加大和给药时间的延长,Ⅴ组死亡2只,Ⅵ组死亡4只;心率(HR)由增加到逐渐恢复,但5 h后,Ⅵ组HR极显著低于对照组(P＜0.01);左心室收缩压(LVSP)和左室内压最大变化速率(±dp/dtmax)呈逐渐下降趋势,左心室舒张末压(LVEDP)则逐渐升高,给药5 h后,Ⅳ、Ⅴ和Ⅵ组LVSP极显著低于对照组、Ⅰ、Ⅱ和Ⅲ组(P＜0.01),Ⅴ和Ⅵ组极显著低于Ⅳ组(P＜0.01)。Ⅱ组LVEDP显著高于对照组和Ⅰ组(P＜0.05),Ⅲ和Ⅳ组显著高于Ⅱ组(P＜0.05),极显著高于对照组和Ⅰ组(P＜0.01)。Ⅴ、Ⅵ组极显著高于其他各组(P＜0.01);Ⅰ~Ⅴ组呼吸逐渐加深加快。5 h后,Ⅲ、Ⅳ和Ⅴ组呼吸率显著高于对照组、Ⅰ和Ⅱ组(P＜0.05),但Ⅵ组呼吸率极显著低于Ⅲ、Ⅳ和Ⅴ组(P＜0.01)。提示替米考星在治疗雏鸡疾病时饮水安全使用剂量为400~600 mg/L,超过800 mg/L时会对心肺功能产生明显影响。     

37℃持续热应激对肉鸡动脉压的影响

80羽25日龄商品代雄性AA肉鸡随机分为对照组(21℃~24℃,相对湿度50%±5%)和试验组(37℃±0.5℃,相对湿度70%±5%),动态监测各组肉鸡的股动脉压(FAP)和生产性能等指标。热暴露使肉鸡平均股动脉压、股动脉收缩压和股动脉舒张压极显著下降(P<0.01);平均股动脉压与呼吸频率、体温呈极显著负相关(P<0.01)。结果表明,37℃持续热应激使肉鸡的股动脉压极显著下降,股动脉压的变化与肉鸡对热暴露的反应和适应过程密切相关。