Effects of Early Feed Restriction on Performance and Ascites Development in Broiler Chickens Subsequently Raised at Low Ambient Temperature

The objective of this study was to examine the effectiveness of early-age growth limitation, achieved through feed restriction (FR), as a means of reducing ascites mortality in broiler chickens exposed to low ambient temperatures. Feed restriction was applied to broilers from 5 to 11 d of age so as to reduce their weight gain to about 40% of that of control broilers that were fed ad libitum (AL). At the age of 21 d the chickens were exposed to a temperature of 15°C, which induced ascites. By 46 d of age, ascites incidence and mortality in the feed-restricted birds were reduced to 15.79 vs. 36.84% and 7.89 vs. 26.32%, respectively, compared with those in the controls (P < 0.05). After feed restriction was stopped, the FR chickens had accelerated weight gain and improved feed conversion ratio from 11 to 18 d of age (P < 0.05), and by 46 d they had achieved the same body weight as the AL birds. Ascitic broilers had smaller relative breast muscle and spleen weights than those of the healthy broilers at 46 d (P < 0.05). However, the relative weights of lung, heart, and liver and the right ventricle weight per total ventricle weight (RV:TV) ratios were greater in ascitic broilers (P < 0.05). At age 37 d, when ascites had developed but not yet caused mortality, the ascitic broilers had lower plasma concentrations of the thyroid hormones thyroxine and triiodothyronine, and higher hematocrit values (P < 0.05) in comparison with the healthy ones. Ascitic birds also had lower oxygen consumption at 6 wk (P < 0.05), which agrees with information that the terminal stage of the ascites syndrome can be characterized by low oxygen consumption. We concluded that the early-age feed restriction reduced ascites incidence and mortality and prevented reduction of the thyroid hormone concentrations in male broilers reared at low ambient temperature from the age of 3 wk onward.     

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.     

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.     

Increased calcium deposits and decreased Ca2+-ATPase in right ventricular myocardium of ascitic broiler chickens

Right ventricular hypertrophy and failure is an important step in the development of ascites syndrome (AS) in broiler chickens. Cytoplasmic calcium concentration is a major regulator of cardiac contractile function and various physiological processes in cardiac muscle cells. The purpose of this study was to measure the right ventricular pressure and investigate the precise ultrastructural location of Ca(2+) and Ca(2+)-ATPase in the right ventricular myocardium of chickens with AS induced by low ambient temperature. The results showed that the right ventricular diastolic pressure of ascitic broilers was significantly higher than that of control broilers (P < 0.01), and the maximum change ratio of right intraventricular pressure (RV +/- dp/dt(max)) of ascitic broilers was significantly lower than that of the controls (P < 0.01). Extensively increased calcium deposits were observed in the right ventricular myocardium of ascitic broilers, whereas in the age-matched control broilers, calcium deposits were much less. The Ca(2+)-ATPase reactive products were obviously found on the sarcoplasmic reticulum and mitochondrial membrane of the control right ventricular myocardium, but rarely observed in the ascitic broilers. The data suggest that in ascitic broilers there is the right ventricular diastolic dysfunction, in which the overload of intracellular calcium and the decreased Ca(2+)-ATPase activity might be the important factors.     

The effect of breed and intrauterine crowding on fetal erythropoiesis on day 35 of gestation in swine

In a previous report, it was suggested that intrauterine crowding impaired fetal erythropoiesis and that fetal erythropoiesis was accelerated in Meishan pigs during early pregnancy. Because these conclusions were based on limited numbers of observations, the present experiment was undertaken to provide a more extensive investigation of these phenomena. Intact white crossbred gilts, unilaterally hysterectomized-ovariectomized (UHO) white crossbred gilts, and intact Meishan gilts (n = 13 to 16 per group) were mated after at least one estrous cycle of normal duration (17 to 23 d). Gilts were laparotomized at d 35 of pregnancy, the uterine horns were exteriorized and opened near each fetus, and a blood sample was collected from each fetus. The uterine horn was then surgically removed, and each fetus and placenta was weighed. All fetal blood samples were measured for hematocrit, red blood cell number, and hemoglobin. Erythropoietin and the percentages of nucleated cells and reticulocytes were also measured in blood samples from the largest and smallest living fetus in each litter. Fetal hematocrits were not affected by treatment. Blood cell counts were greater (P < 0.01) in fetuses of Meishan gilts than in White crossbred intact or UHO gilts. Hemoglobin was less (P < 0.01) in fetuses of Meishan gilts than in fetuses of White crossbred intact or UHO gilts. The percentages of nucleated (immature) cells and reticulocytes were both less (P < 0.01) in fetuses of Meishan intact gilts. Erythropoietin was also lower (P < 0.01) in fetuses of Meishan gilts. As observed previously, fetal weight was correlated (r = 0.38; P < 0.01) with blood hemoglobin concentration. These results confirm that fetal erythropoiesis in Meishan gilts is accelerated compared with White crossbred gilts. These results are consistent with the hypothesis that faster blood cell development could be beneficial to fetal survival in swine.     

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.     

Effect of difference doses of Newcastle disease vaccine immunization on growth performance,plasma variables and immune response of broilers

Background:As a member of the Paramyxoviridae group,Newcastle disease virus(NDV) is the key causative agent of Newcastle disease(ND) that attacks chickens,turkeys and other avian birds.Surviving birds showed lower feed utilization,growth performance or egg production,which results in severe economic losses.The purpose of this study was to determine the effect of different doses of NDV immunization on growth performance,plasma variables and immune response of broiler chickens.Methods:A total of 480 one-day-old Arbor Acres broilers were randomly administrated with 0,4,6 or 8 doses of NDV at 12 d and 28 d,respectively.Each group consisted often replicates with 12 birds each.Growth performance and organ weight were recorded.Plasma concentration of glucose,total protein,cholesterol,triglycerides and nonesterified fatty acid was determined using commercial kits.The concentration of plasma corticosterone and insulin was measured using commercially available radio immune assay kits.Serum antibody titer and peripheral blood lymphocyte proliferation were also recorded.Results:The results showed that NDV decreased body weight gain(BWG),and increased Feed:Gain ratio at 1-21 d at all doses(P 0.05).Plasma insulin concentration was lower in all immunization groups after the first immunization at12 d(P 0.01).The rest of the plasma indexes were not affected by NDV immunization,including glucose,total protein,cholesterol,triglycerides,nonesterified fatty acid,heterophil/lymphocyte ratio,as well as the proliferation of peripheral blood lymphocyte(P 0.05).Compared with the control group,NDV treatment elevated NDV antibody titer at 10 d after the first inoculation(P 0.05),and at d 5,9 and 13 after the second inoculation(P 0.05).Repeated NDV inoculation had no deleterious impacts on body composition at 42 d,and nutrient accretion rates at 8-42 d(P0.05).Conclusions:In conclusion,NDV challenge decreased BWG and feed efficiency in earlier stage of growth.However,NDV treatment at 6 doses down-regulated the Feed:Gain ratio by 6.36%throughout the whole growing period.These data suggest that appropriate lower doses of NDV inoculation increase feed efficiency of broiler chickens.     

Cold-induced ascites in broiler chickens and its improvement by temperature-controlled rearing

Pulmonary hypertension syndrome (PHS), also known as ascites, in broiler chickens prevailed in the local area of Ibaraki prefecture, Japan, and was investigated epidemiologically, serologically, and pathologically. PHS developed in chickens older than 35 days of age when rapid increase of body weight started. Approximately 90% of affected birds were males, in which weight increase was greater than in females. Serologic test revealed that PHS broilers had an increase of hematocrit value. Pathologic studies indicated that the heart of affected birds had an obese-induced pressure and cold exposure triggered congestion in the right ventricle/cava and an increase in peritoneal fluid. These changes were consistent with the previous reports of PHS, so we designed the experiment of effects on cold-induced PHS birds in a temperature-controlled house. After the 10 PHS birds at 55 days were reared for 14 days in a temperature-controlled house at 20 +/- 5 C, ascites disappeared in eight birds and hematocrit values decreased to normal range in nine birds. Our finding indicated that temperature-controlled environment may be one solution to reduce mortality in PHS birds.     

Effects of different crating periods on selected biochemical indices in broiler chickens

Effects of different crating periods on selected biochemical indices were monitored in a group of unsexed ROSS 308 broiler chickens aged 42 days. 120 randomly selected chickens were weighted and placed in 15 heavy duty plastic crates with reduction in floor space approx. 160 cm2/kg of body weight of broilers (average body weight was 2.75 kg). Five crates were kept for 4 hours (Group 4h), another five crates for 8 hours (Group 8 h) and another five crates for 12 hours (Group 12h). After tested periods of crating the broilers were released and blood samples were withdrawn from Vena bosilico in 24 randomly selected birds from each group (Groups 4 h, 8 h, 12 h respectively) and also in other 24 randomly selected non-crated control birds. The results of our experiment proved that duration of crating significantly influenced the stress response in broiler chickens. The duration of crating period was positively correlated with the plasma corticosterone level and negatively correlated with the lactate dehydrogenase, cholesterol, triglycerides, glucose and lactate levels in the blood of broiler chickens.     

Effects of Fusarium mycotoxins with yeast cell wall absorbent on hematology,serum biochemistry,and oxidative stress in broiler chickens

The objectives of the present study were to investigate the toxicity of feed-borne Fusarium mycotoxins on hematology, serum biochemistry, and oxidative stress of broiler chickens, and to evaluate the efficacy of yeast cell wall adsorbent (YCW) in preventing mycotoxins-induced adverse effects. A total of 300 one-day-old Arbor Acres broiler chickens (mixed sex) were randomly divided into 3 groups and received different treatments (5 repetitions per treatment). Treatments were control, naturally contaminated diet (NCD; aflatoxin, 102.08 mg/kg; zearalenone, 281.92 mg/kg; fumonisin, 5,874.38 mg/kg; deoxynivalenol, 2,038.96 mg/kg), and NCD + 2 g/kg of YCW. Broilers fed NCD showed elevated serum alanine transaminase, aspartate transaminase, alkaline phosphatase, γ-glutamyl transferase (GGT), and malondialdehyde (MDA) at 21 d, and alanine transaminase, GGT, creatine kinase, and MDA at 42 d. Higher white blood cell, lymphocyte (LYM), platelet, red blood cell, hemoglobin, hematocrit, and mean corpuscular hemoglobin counts at 21 d, as well as LYM in whole blood and hepatic mRNA expression of heat shock protein 70 at 42 d were also observed in broilers fed with NCD compared with the control diet. However, lower mean corpuscular volume at 42 d and total superoxide dismutase (T-SOD) at both 21 and 42 d were observed in broilers with the NCD treatment when compared with those with the control treatment. Dietary addition of YCW at the level of 2 g/kg in addition to the NCD treatment showed a positive protective effect on GGT, T-SOD in serum, white blood cells, LYM, platelets, and hemoglobin in whole blood at 21 d, and T-SOD, MDA in serum, LYM, mean corpuscular volume in whole blood, and hepatic mRNA expression of heat-shock protein 70 at 42 d. It is suggested that feeding NCD for 42 d might result in a deleterious effect on broiler chickens, and addition of 2 g/kg of YCW can partly attenuate the detrimental effects of the NCD feeding.     

Ultrastructural demonstration of mitochondrial calcium overload in myocardial cells from broiler chickens with ascites and induced hypoxia

Two groups of young broiler chickens, namely, naturally occurring field cases of ascites and those with an induced hypoxia, were used in an ultrastructural study to examine the localisation and distribution of intracellular Ca²⁺ in cardiomyocytes. Age-matched healthy flockmates were used to control each group. Deposits of Ca²⁺ were located extensively in the mitochondria, sarcoplasmic reticulum and Golgi apparatus and sometimes in the myocyte and endothelial cell nuclei of both groups of birds. The results suggest that the cells from the hearts of the ascitic broilers may have been exposed to hypoxia since a large proportion of control material showed no Ca²⁺ activity in either mitochondria or nuclei. The presence of a Ca²⁺ overload in the mitochondria of cardiomyocytes from ascitic birds reared at low altitude or sea level suggests that these broilers were suffering from the deleterious effects of chronic hypoxia due to poor or reduced oxygen use.     

Progressive bradycardia,a possible factor in the pathogenesis of ascites in fast growing broiler chickens raised at low altitude

1. The first objective was to evaluate baseline heart rate (HR) responses in fast growing broilers fed ad libitum from 1 to 45d or subjected to a food restriction (85%, 70% and 55% of ad libitum from 7 to 21d) and a refeeding (22 to 45d) regimen in a normal thermal environment. The second was to evaluate HR and haematocrit responses in fast growing broilers reared at a low environmental temperature and fed ad libitum (A-L) from 1 to 42d, subjected to food restriction (70% ad libitum ) between 7 to 21d and refed thereafter (R-R), or subjected to food restriction between 7 to 42d (R), and to follow the changes in normal birds and those prone to ascites. 2. The baseline HR in the normal thermal environment at 21 and 45d in birds fed ad libitum was lower (P < 0.001) than at 7d. The food-restricted groups had higher HRs at 21d than at 7d, with the differences significant (P < 0.01) for the 70% and 55% treatments. At 21d the HRs in restricted groups were significantly higher (P < 0.01) than in ad libitum -fed birds. After returning to ad libitum feeding the HRs in these birds tended to decline, with the differences significant (P < 0.05) for the 70% and 55% treatments. 3. In the birds exposed to cold, each feeding regimen produced distinct patterns of change in HR and haematocrit. Both feeding regimen and age had significant (P < 0.001) effects on the changes of both variables. Relative to 7d, on 14d and 21d the HRs decreased and haematocrits increased in all groups, but the rates of change were highest in the A-L and R-R birds. The first fulminant cases of ascites were observed during the third week in the A-L group and during the fourth week in the R-R group. None of the chickens from the R group developed ascites. Altogether, the incidence of ascites was 48% in the A-L group and 28% in the R-R group. 4. Among the birds exposed to cold, the ascitic birds had significantly (P < 0.001) lower HRs and higher haematocrits than normal birds from the same feeding regimen group. The time trends in the rates of change in HR and haematocrit were distinctly different (P < 0.001) for ascitic and normal birds. The change in feeding regimen from restricted to ad libitum in the R-R group resulted in a significant (P < 0.001) decrease in HR and increase in haematocrit. 5. In view of the evidence presented, it appears that hypoxaemia and tissue hypoxia in broiler chickens may be a result of circulatory insufficiency associated with progressive bradycardia rather than, as commonly believed, pulmonary insufficiency. In this situation the pulmonary hypertension may be a secondary symptom.     

Blood variables and body weight gain on the first day of life in crossbred pigs and importance for survival

Improving survival is a continuous objective in swine breeding. The aim of this study was to record 22 blood variables and BW gain on the first day of life in Landrace-Yorkshire-Duroc crossbred piglets and to find associations between these variables and survival at weaning. All live piglets from 18 litters were weighed and blood sampled at birth and on d 1 and were monitored to weaning at the age of 5 wk. A total of 261 piglets were born, of which 8.8% were stillborn. Additionally, 15.1% died before weaning. The blood variables glucose, immunoglobulins, and white blood cells increased from birth to d 1 (P < 0.001), whereas α(1)- and β(1)-globulin, red blood cells, hemoglobin, and hematocrit decreased (P < 0.001). At birth, concentrations of lactate (P = 0.004), pH (P = 0.007), red blood cells (P = 0.017), hemoglobin (P = 0.018), and hematocrit (P = 0.052) were associated with survival to weaning. Also, concentrations of lactate increased (P = 0.030) and pH decreased (P < 0.001) when piglets were born in the last third of a litter. On d 1, concentrations of glucose (P = 0.015), hemoglobin (P = 0.025), and BW gain (P = 0.001) were all decreased in piglets that did not survive to weaning. Body weight gain also decreased (P = 0.005) when piglets were born in the last third of a litter. Concentrations of IgG on d 1 was not associated with survival at weaning (P = 0.230) but decreased (P < 0.001) when piglets were born in the last third of a litter. We conclude that several blood variables recorded at birth and on d 1 and BW gain on d 1 were highly associated with survival at weaning and that piglets born in the last third of the litter had less favorable vitality.     

Vascular remodeling and its role in the pathogenesis of ascites in fast growing commercial broilers

This study examined the putative role of blood vessel pathology in the development of ascites in broilers. Major blood vessels (aorta, brachiocephalic arteries, pulmonary arteries, and vena cava) from normal commercial male broiler chickens, and broilers that developed congestive heart failure (CHF) with or without ascites were subjected to gross and microscopic examination.On cross-section, grossly, the arteries from normal broilers and those showing dilated cardiomyopathy without ascites appeared circular, with firm wall tone characteristic of the normal artery. In contrast, the arteries from ascitic broilers appeared flaccid and lacked elasticity, which was evidenced by collapsing, ellipsoid cross-sectional arterial lumen owing to the structural weakness of the arterial walls. Microscopically, ascitic broilers showed thinning or occasionally total loss of elastic elements in the arterial wall, and reduced network density of the structural matrix of the vascular wall, as well as increased thickness of fibers in vena cava.The structural changes seen in the major arteries from ascitic broilers are maladaptive, and as such would definitively impose an increased hemodynamic burden on the already failing heart pump. The changes in veins are indicative of pathological remodeling conducive to increased permeability of the vascular wall, particularly in the situation when a poorly distensible structure is further subjected to wall stress associated with increased pressure and volume overload. Taken together, increased hemodynamic burden and reduced structural density of the venous wall constitute conditions conducive for seepage and accumulation of ascitic fluid.     

Decreased thyroxine, triiodothyronine, and 5'-deiodination levels in malabsorption syndrome (runting or stunting syndrome) in artificially inoculated broilers

The effect of malabsorption syndrome (stunting or runting syndrome) on the thyroid function of broilers was investigated in control and inoculated broilers from 1 to 29 days of age. The broilers were infected at 1 day of age with intestinal homogenates from chickens naturally suffering from this syndrome. The body weight of inoculated broilers was significantly (P less than 0.05) lower 1 week after inoculation than that of controls. The level of thyroxine in the serum of inoculated birds was lower (P less than 0.05) from day 6 through the remainder of the trial. The level of triiodothyronine of inoculated birds was depressed (P less than 0.05) on day 4, but 1 week later it returned to normal. The earliest phenomenon indicative of disturbance of thyroid function was the significant depression of 5'-deiodination in liver homogenates of inoculated broilers as early as day 2. It is concluded that thyroid function is one of the earliest targets of this syndrome.     

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。     

笼养和地面平养对肉鸡生产性能的影响

分别于夏季采用7日龄AA肉鸡公雏264只,春季采用7日龄AA肉鸡和北京油鸡公雏各144只,分成2组,每组6个重复,进行地面平养和笼养生产性能比较试验,结果表明:夏季笼养AA肉鸡2～4周龄日增重低于地面平养(P<0.05),5周龄时高于地面平养(P<0.01);春季笼养AA肉鸡2周龄日增重、日采食量和体重高于地面平养(P<0.05);但笼养对AA肉鸡全期平均日采食量、平均日增重、试验末体重、饲料转化率、死亡率没有影响(P>0.05)。笼养北京油鸡表现为3～6周龄平均日采食量、体重高于地面平养(P<0.05),笼养对北京油鸡平均日增重、饲料转化率和死亡率没有影响(P>0.05)。     

Nonspecific innate immunity against Escherichia coli infection in chickens induced by vaccine strains of Newcastle disease virus

The objective was to test the hypothesis that vaccine strains of Newcastle disease virus (NDV) induce nonspecific immunity against subsequent infection with Escherichia coli. White leghorn chickens at 5 wk of age were vaccinated with a NDV vaccine at various days before challenge exposure with O1:K1 strain of E. coli via an intra-air sac route. Immunity was determined on the basis of the viable number of E. coli in the spleen 24 hr after the infection. Roakin strain induced significant (P < 0.05) immunity against E. coli at 4, 6, and 8 days, and La Sota strain at 2, 4, and 8 days, postvaccination. Secondary NDV vaccination administered 14 days later failed to induce immunity against E. coli when chickens were infected 1 or 5 days after the vaccination. Significant (P < 0.05) suppression of this nonspecific immunity was observed in birds treated with corticosterone, 40 mg/kg in feed, given for three consecutive days immediately prior to the bacterial exposure but not in those treated prior to the period. The results indicate that innate immunity induced by the primary NDV vaccination may significantly suppress the multiplication of E. coli in chickens for a period of 2-8 days postvaccination. The NDV-induced immunity was inhibited by corticosterone, which is known to mediate physiological responses to stress.     

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.     

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.