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Femoral bone degeneration has been recognized as an important cause of lameness in broiler chickens for many years, but the pathogenesis of this condition has not been completely elucidated. The current work presents comprehensive analyses of changes associated with femoral bone degeneration based on findings from gross pathology, histopathology, biochemistry, and synchrotron-based imaging techniques. Gross lesions were predominantly seen in epiphysis and metaphysis of the proximal femur, and infrequently in distal femur, but we did not observe gross lesions in the diaphysis. Bone fractures were observed occasionally, but the most common lesions involved separation of articular cartilage of the femoral bone head, with progressive erosions of the subchondral bone. In advanced cases, on histopathological examination, changes in femoral bone were indicative of chondronecrosis and osteonecrosis. Computed tomography revealed that the degenerative process involves loss of trabecular bone. The course of the lesion development in the mineralized matrix appears to be coupled with increased bone resorption associated with excessive proliferation of pathologically altered osteoclasts. Light microscopy, Fourier transform infrared spectroscopy, and biochemical analysis provided consistent evidence that lowered protein content of the bone organic matrix is an integral component of femoral bone pathology, but these changes do not appear to be associated with excessive activity of matrix metalloproteinases. Taken together, our findings indicate that femoral bone degeneration is associated with structural changes occurring in both inorganic and organic matrix of the bone, but insufficiency in protein metabolism is most probably a primary aetiological factor in the natural history of femoral bone degeneration. However, it is important to stress that our findings do not negate the importance of bacterial infection in the evolution of this condition. Pathogens play a critical role in the progressive pathogenesis of this condition, which ultimately is manifested, in most instances, as femoral head necrosis.

The present work describes specific congenital intestinal accidents found in commercial broiler chickens where the affected individuals have their intestinal loops translocated outside the abdomen. These anomalies have been observed in many embryos that failed to hatch, in newly hatched chicks, as well as in broilers at various stages of growth. It appears that these lesions stem from incomplete closure of the abdominal cavity during the last stages of embryonic development.

Thermal processing of meat products generates cardiotoxic compounds capable of inducing heart failure in both humans and laboratory animals. Such compounds may be present in broiler diets because supplements such as meat meal (MM), which are commonly used in broiler rations, are rendered at high temperature. Our objective was to evaluate whether putative cardiotoxic compounds in MM increase the risk of heart failure in broilers. The treatment and control diets were prepared by mixing the condensed MM extract (equivalent to dietary MM inclusion of 25%) or placebo (condensed extraction medium) with commercial broiler feed, and the respective diets were offered to commercial male broilers randomly allocated to either treatment or control groups. Broilers fed a diet spiked with MM extract showed a higher incidence (P<0.05) of chronic heart failure (65.5%) in comparison with the control group (55.4%). Postmortem examination upon termination of the experiment revealed that, in comparison with control broilers, broilers fed diet containing MM extract showed higher incidence of lesions indicative of subclinical heart disease evidenced grossly by ventricular dilation and pericardial effusions, microscopically by changes characteristic of cardiomyocyte degeneration, and ultrastructurally by changes in contractile elements and in mitochondria. Measurements of cardiac high-energy phosphates revealed that broilers fed the diet containing MM extract had lower (P<0.05) levels of cardiac energy reserve as compared with birds fed control diet. We conclude that cardiotoxic factors that can induce patho-physiological changes in the heart are present in MM.

1. It has recently been shown that oxidative stress is involved in the pathogenesis of congestive heart failure (CHF) in broiler chickens. Vitamins E and C, common antioxidants, have been advocated for the prevention of heart failure in humans. The present study examines the effects of supplementation of these vitamins on incidence of CHF and prevention of oxidative stress in the myocardium. 2. Commercial male broilers were randomly allocated to three experimental groups and, respectively, offered commercial broiler diet (control), commercial diets fortified with vitamin E (960 IU/kg) or vitamin C (400 mg/kg). The broilers were monitored daily for overt signs of heart failure and clinical data including ECG and blood gas analysis were collected periodically. Lipid peroxidation was measured in cardiac tissues from apparently normal broilers and broilers developing CHF in each group using thiobarbituric acid reactive substances (TBARS) assay. 3. Overall, the incidence of CHF in broilers given diets fortified with vitamin E or vitamin C was not significantly different as compared to the control group. The incidence of overt signs of hypoxaemia was lower in the vitamin C group than in the control group. Lipid peroxidation was highest in broilers that developed CHF as compared to apparently normal broilers fed either vitamin E or C fortified diets. Neither vitamin E nor vitamin C was effective in preventing oxidative damage in broilers that developed CHF. 4. In conclusion, the present study confirmed that oxidative stress is involved in the pathogenesis of heart failure in broilers, but dietary supplementation of antioxidant vitamins did not prevent oxidative damage in broilers that developed CHF. Beneficial effects of vitamin C supplementation were evidenced by lower incidence of hypoxaemia, and the tendency to reduce the susceptibility of broilers to heart failure. However, vitamin E did not have any impact on clinical status or the incidence of CHF.

The present study examined the possible role of reactive oxygen species in the pathogenesis of heart failure in broilers. Data were collected from three groups of birds at various risk of heart failure: Leghorn chickens (resistant to heart failure), slow-growing feed-restricted broilers (low risk of heart failure), fast-growing ad libitum fed broilers (high risk of heart failure), and broilers with congestive heart failure (CHF). In the first part of the study, basic clinical parameters and ultrastructural changes were examined in the context of lipid peroxidation of the ventricular myocardium. This was followed by the study of in vitro changes in the activity of selected cytosolic enzymes (creatine kinase and lactate dehydrogenase) and mitochondrial enzymes (pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase) in the presence of oxidants (hydrogen peroxide or tertiary butyl hydroperoxide). The distinctive clinical feature in the fast-growing broilers and in the broilers with CHF as compared with slow-growing broilers or Leghorn chickens was a significantly lower heart rate (P <0.05). Electron microscopy revealed marked morphological changes in myocardial mitochondria in these broilers (i.e. fast-growing broilers and broilers with CHF). The level of malondialdehyde equivalents, an indicator of lipid peroxidation subsequent to generated oxidative stress, was significantly higher (P <0.05) in ad libitum fed broilers and was highest (P <0.01) in broilers with CHF. In vitro, the presence of oxidants had a detrimental effect on creatine kinase and alpha-ketoglutarate dehydrogenase activity, while lactate dehydrogenase activity increased. The activity of pyruvate dehydrogenase was not altered by oxidants. Our results indicate that the deterioration of heart function in fast-growing commercial broilers in our experimental model is associated with oxidative stress leading to lipid peroxidation of cellular and mitochondrial membranes, and decreased activity of myocardial creatine kinase and alpha-ketoglutarate dehydrogenase enzymes critical for energy synthesis and transformation pathways.

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.

Plant-based simple phenolics are natural antimicrobial and antioxidant compounds that may possess biological activity when included in animal diets. Previous work in our lab has shown that sinapic acid (SA) found in canola meal improves nutrient retention and alters gut microbiota when fed at low levels (0 to 0.10%) to broiler chickens. It was of interest to investigate the effect of dietary SA in laying hens that possess a more mature intestinal microbiota. Therefore, 2 experiments were conducted to determine the effects of dietary SA on performance, nutrient digestibility, and egg quality in laying hens. Sinapic acid (Sigma-Aldrich, 98% purity) was included in diets at 0, 0.025, 0.050, and 0.075% in experiment 1, and 0 and 0.5% in experiment 2. Both experiments were conducted for 21 d. Dietary treatment did not affect production traits and gastrointestinal tract volatile fatty acid production in either experiment. Apparent metabolizable energy and protein digestibility were also unaffected by treatment in experiment 1, but in experiment 2, feeding 0.5% SA increased both AME(n) and protein digestibility in comparison to the unsupplemented control. Egg weight, albumen weight, yolk weight, egg specific gravity, shell thickness, and Haugh units were not significantly affected by dietary treatments in either of the experiments. Sinapic acid was not detected in eggs from experiment 1 but in experiment 2, low levels of SA were detected in both the yolk and albumen of eggs from hens fed 0.5% SA. Further research is needed to more completely define the relationship between dietary SA level and nutrient utilization as well as the accumulation of SA in egg components.

Broiler chickens (Gallus gallus) genetically selected for rapid growth are inherently predisposed to heart failure. In order to understand the biochemical mechanisms associated with the deterioration of heart function and development of congestive heart failure (CHF) in fast-growing chickens, this study examined several factors critical for myocardial energy metabolism. Measured variables included cardiac energy substrates [creatine phosphate (CrP), adenosine triphosphate (ATP), l-carnitine], activity of selected cytosolic enzymes [creatine kinase (CK; EC 2.7.3.2), lactate dehydrogenase (LDH; EC 1.1.1.27)] and mitochondrial enzymes [pyruvate dehydrogenase (PDH; EC 1.2.4.1), alpha-ketoglutarate dehydrogenase (alpha-KGDH; EC 1.2.4.2)]. The CK activities were higher in fast-growing and CHF broilers as compared to slow-growing broilers (p<0.05). Cardiac LDH and alpha-KGDH activities were not changed (p>0.05), whereas PDH activity was highest (p<0.05) in broilers with CHF. Deterioration of heart function is correlated with lowered cardiac ATP, CrP, and l-carnitine levels (all p<0.05). Depletion of high energy phosphate substrates, ATP and CrP, is evident in fast-growing chickens and those that developed CHF. Increased activity of CK suggests that cardiac energy management in fast-growing broilers and those with CHF largely depends on contribution of this pathway to regeneration of ATP from CrP. In this scenario, inadequate level of CrP is a direct cause of ATP insufficiency, whereas low cardiac l-carnitine, because of its role in fatty acid transport, is most likely an important factor contributing to shortage of key substrate required for synthesis of cardiac ATP. The insufficiencies in cardiac energy substrate synthesis provide metabolic basis of myocardial dysfunction in chickens predisposed to heart failure.

In order to explain the biochemical mechanisms associated with deteriorating heart function in broiler chickens, this study compared myocardial high energy phosphate substrates in leghorns, feed restricted (Broilers-Res) broilers, ad libitum fed broilers (Broilers-AL), and in broilers that developed heart failure and ascites. The profile of adenine nucleotide content in the heart tissue did not differ between leghorns and Broilers-Res, but there were significant differences among Broilers-Res, Broilers-AL, and broilers with ascites. During intensive growth periods, leghorns and Broilers-Res showed increasing trends in heart ATP levels, whereas in fast growing broilers the heart ATP declined (p<0.021). ATP:ADP and ATP:CrP ratios increased with age in both leghorn and Broilers-Res, declined in fast growing broilers, and were the lowest in broilers that developed heart failure. The changes in heart high energy phosphate profile in broilers suggest that the energy demand of the heart during a rapid growth phase may exceed the bird's metabolic capacity to supply adequate levels of high energy phosphate substrate. The insufficiency of energy substrate likely contributes to the declining heart rate. In some individuals this may lead to impaired heart pump function, and in more severe cases may progress to heart pump failure.

The present study examined several basic attributes of first-line defence mechanisms in the skin as potential factors that may explain the susceptibility of broiler chickens to cellulitis. The variables including structural characteristics of the skin, physicochemical properties and cellular responses to the challenge with pathogens were compared between two categories of chickens, a strain of fast-growing commercial broiler chickens (susceptible to cellulitis) and leghorn chickens (resistant to cellulitis). There were substantial differences between leghorns and broilers with regard to physiological characteristics of the skin. Broiler skin was more amenable to injury and the wound-healing process was slow. Compared with leghorns, the lesions resulting from sub-dermal challenge in broilers were more severe and disseminated over a larger area. Mobilization of phagocytic cells (heterophils and macrophages) in leghorns was brisk even in the areas distant from the site of infection, whereas only few heterophils were recruited in the skin of broilers. The functional competence of heterophils in broilers was inferior when compared with leghorns. Based on the present finding, the predisposition of broilers to cellulitis appears to be primarily associated with the inferior first line of defence of their skin. Broilers in commercial situations may be at higher risk to succumb to even minor infection and eventually develop cellulitis because: (1) structural weaknesses of the skin may predispose broilers to skin injury and thus the risk of skin infection by pathogens is increased; (2) broiler skin surface is more likely to provide a conducive environment for colonization of Escherichia coli; (3) in the event of infection, poor recruitment of phagocytic cells to the site of infection may readily lead to widespread colonization of the tissue by pathogens causing cellulitis and (4) poor functional quality of the phagocytic cells that are mobilized compromise the ability of the host to contain the spread of infection.

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.

In comparison to other classes of chickens, broilers selected for rapid growth tend to be hypoxaemic, and many develop congestive heart failure (CHF). In order to explain the physiological mechanisms associated with hypoxaemia in fast-growing broiler chickens (Gallus gallus), this study examined several basic physiological parameters including the blood gas profile in arterial [left atrial (LA)] and mixed venous [right atrial (RA)] blood, systemic oxygen extraction ratio, and intrapulmonary shunt fraction. These parameters were further studied in the context of blood flow in the pulmonary circulation, structural characteristics of the lungs, and cardiac function [measured as cardiac index (CI)]. Overall, broilers had lower arterial and mixed venous blood pO(2) levels and higher pCO(2) levels compared to leghorns. The cardiac index was lower in fast-growing and CHF broilers compared to leghorn chickens or feed-restricted broilers. Systemic oxygen extraction ratio (ER) and intrapulmonary shunt fraction were significantly higher in fast-growing broilers and birds with CHF (all P<0.01). Lungs of all broilers, but not leghorns, contained ectopic, irregular nodular formations located within air spaces. Broilers with clinical signs of hypoxaemia revealed the highest number of these formations in their lung. Taken together, the present findings indicate that key factors associated with the development of hypoxaemia in fast-growing broilers include: (1) high demand for oxygen as evidenced by high oxygen ER; (2) inadequate cardiac output (CO) to fulfill the higher oxygen demands, leading to severe depletion of O(2) in mixed venous blood; and (3) elevated intrapulmonary shunt fraction and possibly dead space associated with specific pathological and anatomical characteristics within the lung.

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.

This study describes the adverse effects of dietary lupines in broiler chickens for which lupine seeds (Lupinus angustifolius) in raw, dehulled, or autoclaved forms were used as a replacement for soybean meal (SBM) in practical diets. Test diets contained 35% SBM (control) or raw (40%), autoclaved (40%), or dehulled (35%) lupine seed meal. All diets were isocaloric (3,230 kcal/kg AME) and isonitrogenous (23% crude protein). Each diet was offered ad libitum to a group of 16 (four replicates with four birds per replicate) day-old male broiler chicks for 21 d. Chemical analysis of lupine seeds showed no detectable levels of mycotoxins, and total alkaloid contents were below 0.01%. Decreased food intake and growth rate were the main signs observed in all birds fed lupine-based diets. These adverse effects were observed during the first week and persisted throughout the trial. Acute signs of toxicity were observed in four chicks fed the diet containing raw lupine seed during the first week of exposure. Initial clinical signs included leg weakness, lack of coordination, and torticollis. In later stages, during Weeks 2 and 3, some birds fed lupine-based diets showed signs of muscle paralysis and skeletal deformity. Postmortem examination did not show gross pathological changes associated with the dietary treatments. Liver microsomal cytochrome P-50 content was higher (P < 0.05) in birds fed the raw lupine-based diet (mean 0.56 pmol/mg protein) in comparison with controls (mean 0.25 pmol/mg protein), which indicated a systemic effect. Based on the present results, it can be stated that high levels of some varieties of sweet lupines in broiler diets may cause significant adverse effects manifested as 1) decreased feed intake and growth rate in most of the birds, and 2) specific signs of acute and chronic toxicity in some individuals.

The response of broiler chickens to a wide range of dietary supplementation of thiamine to broiler breeder diet was studied in order to understand the effects of maternal thiamine nutrition on the status of thiamine indices in the offspring. Thiamine, and thiamine pyrophosphate (TPP) content, and alpha-ketoglutarate dehydrogenase (KGDH) activity were measured in hearts from 20 day old chicken embryos and from chickens at 1, 7, 14, and 21 days of age and in blood at 21 days of age. Total thiamine content in the heart of day old chicks was higher in comparison to 20 day old embryos. Maternal supplementation of thiamine increased heart thiamine in the offspring (p < 0.001), and increased the activity of KGDH in the hearts of day old chicks (p < 0.001), but not in the embryo. The TPP content in the heart increased in response to both maternal and offspring thiamine supplementation (p < 0.001), however the effect of broiler thiamine supplementation was largely independent from the maternal effect. The effect of maternal thiamine nutrition on the offspring's heart KGDH activity was apparent, but the responses to broiler supplementation were dependent largely on the maternal effect. Blood TPP content was not affected by maternal thiamine supplementation (p = 0.39), but thiamine supplementation in the offspring diets increased blood TPP (p < 0.001). Both maternal and offspring thiamine supplementation increased blood free base thiamine content (both p < 0.001). It is concluded from this study that maternal thiamine nutrition affects thiamine status indices and thiamine metabolism of the offspring.

Occurrence of mortality, wooden breast, and pulmonary disease in broiler chickens during the last 16 days of production in a teaching flock of 4000 commercial broilers was determined. A new syndrome was identified, in which broilers fell over for an unknown reason and were unable to right themselves (dorsal recumbency). Birds affected by dorsal recumbency were alert and responsive and showed no clinical signs except for occasional mild to moderate dyspnea. When turned over, they resumed normal behavior. Mortality (14 culls; 49 dead) during the last 16 days of production accounted for 1.6% of the flock and 36% of total mortality. Among these, 71% were heavy males, 70% had wooden breast, and 71% had pulmonary congestion and edema. Gross lesions of concurrent wooden breast and pulmonary disease occurred in 68% of the mortality, including 21 of 22 dead birds found on their backs. These findings indicate that wooden breast is associated with mortality prior to processing as a result of pulmonary disease in heavy male broilers. When birds with wooden breast fall onto their backs for unknown reason(s), they are unable to right themselves. If not found and turned over, they may not survive. Based on these findings, wooden breast is likely greater than just a problem with meat quality and should be considered an animal well-being issue.

The present work evaluates trends in the incidence of cellulitis during the last decade using Canadian National Poultry Condemnation Records. In 1986, only 0.048% of the total slaughter broilers were condemned as a result of cellulitis lesions. Over the next 10 yr, steady increments in cellulitis condemnations were observed, and between 1986 and 1996, the percentage of cellulitis condemnation increased 11.8-fold. In 1996, more than 2.6 million broilers (0.568% of total slaughter) were condemned due to cellulitis; this constituted 30.1% of total condemnations, making it the number one condemnation category in 1996. In the context of dynamic increase in cellulitis, the problems concerning meat hygiene and possible health risk to the consumer are deliberated.

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.

A flock of broiler chickens was monitored intensively for overt signs indicative of sudden death. Electrocardiographic tracing of terminal cardiac activity was obtained from six broilers succumbing to sudden death syndrome and from six control chickens which were killed by cervical dislocation. Normal sinus rhythm, heart rate and electrocardiogram (ECG) pattern with P, QRS, and T deflections were observed for two to three minutes in the control chickens. The ECG tracing from birds dying of sudden death syndrome showed no identifiable P, QRS, or T waveforms. Initial more regular oscillatory waves resembling ventricular flutter, changed to irregular, undulating waves characteristic of ventricular fibrillation. A straight line, indicating cessation of heart activity, appeared within four to six minutes of the onset of clinical signs. It was concluded that the sudden death syndrome is associated with an acute cardiovascular failure caused by a lethal cardiac dysrhythmia, ventricular fibrillation.

A study was completed to characterize the electrocardiographic (ECG) patterns of male broiler chickens. Data were collected from 300 commercial broilers. ECG readings were collected from all birds between 12 and 15 days of age and then twice more at 10-day intervals. The measurements. included heart rate and rhythm, QRS complex duration, amplitude and mean electrical axis (MEA), incidence of ascites and incidence of sudden death syndrome (SDS). Eight birds died from SDS and 4 birds died from ascites. Twelve birds were condemned for ascites at the processing plant. The overall population heart rate declined with age. Birds that died of SDS had a higher heart rate, whereas those that developed ascites had a lower heart rate than the remainder of the population. The normal MEA was found to be between 0 degree and 180 degrees. On average 30% of birds showed left or right QRS axis deviation, and this pattern was observed in 14 of the 16 birds that developed ascites. Several types of cardiac arrhythmias were observed, the most common being premature ventricular contractions (PVC). The incidence of PVC increased with age, ranging from 1% at 12-15 days of age to 8.9% at 32-35 days of age. QRS axis deviation was present in 5 SDS birds. It is concluded that some 30% of the broiler flock tested was at risk of developing heart failure or heart-related disease.

Thiamine status in response to a wide range (2 to 32 mg/kg) of dietary supplementation of thiamine was studied in male and female broiler chickens in order to understand the manifestation of marginal thiamine deficiency in chickens. Thiamine content and transketolase (TK) activity, were measured in tissues (brain, heart, liver) and blood samples from chickens at 1, 7, 14, 21, 35, and 42 days of age. There was no correlation between body weights and tissue thiamine or TK activity at 3 or 6 weeks of age. Overall thiamine supplementation did not have significant effects on TK activity in the liver (p = 0.22) or brain (p = 0.07). Males had a higher concentration of thiamine than females (p < 0.001) in livers and brains, but the level in the heart did not differ significantly between sexes. There were substantial contrasts among tissues in changes in the tissue thiamine content in response to dietary thiamine levels. Relative to day 1, unsupplemented birds' heart, brain, and liver thiamine increased by 34, 30, and 31% respectively. In response to supplementation, the heart tissue tended to accumulate thiamine at a considerably higher rate than liver or brain. Blood thiamine concentration tended to decline in unsupplemented birds and those supplemented at 2 and 4 mg/kg levels, whereas in birds supplemented with 8 mg blood thiamine level increased at day 7 and remained relatively constant for the remaining part of the trial. Supplementation at the levels of 16 and 32 mg/kg resulted in blood thiamine increasing throughout the duration of the trial. The presented data indicate that there are organ specific differences in the requirement for thiamine. The heart appears to have a higher requirement than the liver or brain. Since there are potential beneficial effects of thiamine on the heart, this subject deserves more detailed investigation.

The effect of aspirin on intestinal lesions was evaluated in birds undergoing an experimental challenge with Clostridium perfringens as part of a model for inducing subclinical necrotic enteritis (SNE). Broilers were raised on clean wood shavings and randomly assigned to three treatments: Uninfected (U), Infected (I), and Infected + Aspirin (I+A; 0.025% acetylsalicylic acid in drinking water during days 21-25). Birds in the I and I+A groups were gavaged with Eimeria maxima on day 18 and their feed was inoculated with C. perfringens (1 × 10 9 CFU/bird) during days 23-25. On day 26, birds were euthanatized, intestinal lesions were evaluated, and intestinal tissue was collected for qPCR assessment of genes thought to be involved in the immune response to SNE: IL-1β, IL-10, MMP-2, and MMP-7. Birds in the I+A group had more-severe and numerous lesions compared to the I group. For all genes except MMP-2, expression was upregulated in the I group compared to the U group, but did not differ between the I and I+A groups. These results indicate that aspirin exacerbated the intestinal lesions associated with this disease. Aspirin could play a role in the development of a reliable and consistent model for the induction of necrotic enteritis under experimental settings.

Routine and quantitative histologic studies on femoral head separation (FHS) associated with coxofemoral joint disarticulation at necropsy were conducted on 125 femoral heads collected from 21- to 50-day-old clinically normal broilers. The study compared groups demonstrating grossly detached femoral heads (DFHs) with those having attached femoral heads (AFHs). Marked microscopic lesions compatible with osteochondrosis (OCD) consistently occurred along the separation surface in the DFH population. The histologic changes consisted of cartilage degeneration and necrosis sometimes forming small clefts or microfractures. Hemorrhage and less frequent inflammatory cells were often present along the separation surfaces. Small foci of OCD in the femur occurred in the AFH group with lesser frequency and severity. The histologic changes were mainly found within the proximal proliferative zone of the physis near the epiphyseal junction. Histomorphometry disclosed significant quantitative reductions in chondrocyte density with increased pyknosis occurring adjacent to the separation site and to a lesser extent in deeper regions of the growth plate for the DFH compared with AFH. Measurements made along the separation surface of the percentage length occupied by osteochondrotic defects and actual separated cartilage disclosed significant differences between evaluation groups. However, determinations of vascular canal areas present within two or more regions of the growth plate revealed a slight and significant increased area for DFH compared with AFH. Severity scores for the occurrence of microthrombi within the growth plate showed no difference between the groups. The pathogenesis of FHS in broilers is related to defective cartilage production or degeneration resulting in increased fragility. This contrasts with the proposed pathogenesis of OCD in mammals, which involves ischemic necrosis due to underlying vascular defects. The results for the FHS-disarticulation model also differ from those reported for glucorticoid-induced femoral head necrosis in broilers. The FHS-associated lesions occurred without histologic evidence of bacterial chondritis or osteomyelitis.

Chicken domestication began at least 3,500 years ago for purposes of divination, cockfighting, and food. Prior to industrial scale chicken production, domestication selected larger birds with increased egg production. In the mid-20th century companies began intensive selection with the broiler (meat) industry focusing on improved feed conversion, rapid growth, and breast muscle yield. Here we present proteomic analysis comparing the modern broiler line, Ross 708, with the UIUC legacy line which is not selected for growth traits. Breast muscle proteome analysis identifies cellular processes that have responded to human directed artificial selection. Mass spectrometry was used to identify protein level differences in the breast muscle of 6-day old chicks from Modern and Legacy lines. Our results indicate elevated levels of stress proteins, ribosomal proteins and proteins that participate in the innate immune pathway in the Modern chickens. Furthermore, the comparative analyses indicated expression differences for proteins involved in multiple biochemical pathways. In particular, the Modern line had elevated levels of proteins affecting the pentose phosphate pathway, TCA cycle and fatty acid oxidation while proteins involved in the first phase of glycolysis were reduced compared to the Legacy line. These analyses provide hypotheses linking the morphometric changes driven by human directed selection to biochemical pathways. These results also have implications for the poultry industry, specifically Wooden Breast disease which is linked to rapid breast muscle growth. [ABSTRACT FROM AUTHOR]

No study has demonstrated the use of dietary Cannabis-derived cannabidiol (CBD) to alter the stress response in chickens or examined its effects on meat volatile compounds (VOCs). Here, we subjected chickens to dysbiosis via C. perfringens infection or Escherichia coli lipopolysaccharide (LPS) treatment and investigated the potential link between meat VOCs and cecal bacterial activity and the ameliorative effect of CBD. The cecal bacterial production of short-chain fatty acids (SCFAs) was closely correlated with meat VOCs. CBD supplementation reduced the formation of breast meat spoilage VOCs, including alcohols, trimethylamine and pentanoic acid, in the challenged birds, partly by decreasing cecal putrefactive SCFA production. Meat VOC/cecal SCFA relationships differed according to the challenge, and CBD attenuated the effects of C. perfringens infection better than the effects of LPS challenge on meat VOCs. These findings provide new insights into the interactions among bioactive agent supplementation, gut microbiota activity and meat properties in birds. [ABSTRACT FROM AUTHOR]

The objective of this study was isolating and characterising Clostridium perfringens from chickens in Vietnam and identifying virulence factors involved with enteritis. Five hundred thirty-one faecal and sixty-eight intestinal samples were collected from healthy and diseased chickens for the C. perfringens isolation. The presence of virulence factors was determined by multiplex PCR. The netB gene of the selected isolates was sequenced and checked for its expression by SDS-PAGE. Two hundred seventy-two C. perfringens isolates were collected. All of them were shown to be positive for the cpa gene. The netB gene was detected in 26.56% of the C. perfringens isolates from the healthy chickens, while 43.45% of the isolates from the faeces and 45% of the isolates from the intestinal samples were positive for this gene in the diseased birds. All eight isolates positive to netB from the diseased chickens showed 100% identity in the netB sequence and produced the NetB toxin in vitro, whereas only two out of eight healthy chicken-derived isolates produced this toxin. Nine out of ten chickens experimentally infected with the C. perfringens netB-positive isolate showed typical signs of enteritis. The cpa gene was the most prevalent virulence factor identified in the bacteria C. perfringens, but the netB gene could be a major player responsible for necrotic enteritis progression in chickens. [ABSTRACT FROM AUTHOR]

Locomotor problems are among one of the main concerns in the current poultry industry, causing major economic losses and affecting animal welfare. The most common bone anomalies in the femur are dyschondroplasia, femoral head separation (FHS), and bacterial chondronecrosis with osteomyelitis (BCO), also known as femoral head necrosis (FHN). The present study aimed to identify differentially expressed (DE) genes in the articular cartilage (AC) of normal and FHS-affected broilers by RNA-Seq analysis. In the transcriptome analysis, 12,169 genes were expressed in the femur AC. Of those, 107 genes were DE (FDR < 0.05) between normal and affected chickens, of which 9 were downregulated and 98 were upregulated in the affected broilers. In the gene-set enrichment analysis using the DE genes, 79 biological processes (BP) were identified and were grouped into 12 superclusters. The main BP found were involved in the response to biotic stimulus, gas transport, cellular activation, carbohydrate-derived catabolism, multi-organism regulation, immune system, muscle contraction, multi-organism process, cytolysis, leukocytes and cell adhesion. In this study, the first transcriptome analysis of the broilers femur articular cartilage was performed, and a set of candidate genes (AvBD1, AvBD2, ANK1, EPX, ADA, RHAG) that could trigger changes in the broiler´s femoral growth plate was identified. Moreover, these results could be helpful to better understand FHN in chickens and possibly in humans. [ABSTRACT FROM AUTHOR]

Effects of pawpaw leaf and seed meals composite mix (PCM) supplementation on broiler chickens were assessed. A total of 396-day-old Arbor Acres broiler chicks were distributed to six diets: 1 = 0 g/kg PCM; 2 = 2 g/kg PCM; 3 = 4 g/kg PCM; 4 = 6 g/kg PCM; 5 = 8 g/kg PCM; and 6 = 10 g/kg PCM. Body weight gain and feed conversion ratio of the birds fed diet 5 was similar to those fed diets 4 and 6 but better than (P < 0.05) those fed diets 1, 2 and 3 at grower phase and overall period of the feeding trial. Alanine aminotransferase (ALT) concentration decreased in the birds with an increase in the dietary PCM supplementation level such that ALT concentration reduction (P < 0.05) was recorded in the birds fed diets 5 and 6 when compared to those fed diet 1. The serum cholesterol in birds fed diets 3, 4, 5 and 6 was similar to the level recorded for birds fed diet 2 but lower (P < 0.05) than the level in birds fed the control diet. The superoxide dismutase and glutathione peroxidase serum concentration improved (P < 0.05) in the birds fed PCM-supplemented diets (2 to 6) compared to those fed diet 1. Catalase serum concentration in birds fed diet 5 was similar to those fed diets 3, 4 and 6 but higher (P < 0.05) than the concentration in birds fed diets 1 and 2. The PCM dietary supplementations (6 g/kg to 10 g/kg) did not affect on the performance and health status of the broiler chickens negatively. [ABSTRACT FROM AUTHOR]

Chromium (Cr) is one of the most important environmental pollutants which are released into the environment due to their wide usage in numerous industries. The excess of Cr (VI) can induce hepatotoxicity, while the molecular mechanism that is involved in Cr (VI)-induced hepatotoxicity is unclear. We demonstrated the induction of chromium poisoning model in chickens to identify the differentially expressed genes (DEGs), and their functions were analyzed under different physiological and pathological conditions. Histopathological examination and transcriptome data for chromium-poisoned livers and control livers were annotated with Illumina® HiSeq 2000. The histopathological examination in chromium poisoning groups showed diapedesis, hemolysis, degeneration, nucleus pycnosis, and central phlebectasia in the liver. A total of 334 genes were upregulated and 509 genes were downregulated. The most strongly upregulated genes were HKDC1, DDX4, ACACA, FDFT1, CYYR1, PPP1R3C, and SLC16A14, while the most downregulated genes were MYBPC3, CCKAR, PCK1, and CPT1A. A Gene Ontology (GO) term with the highest enrichment of DEGs is small molecule metabolic process. In cell component domain, the term with the highest enrichment is extracellular matrix. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways showed that glucose metabolism, lipid metabolism, and protein metabolism were the most important metabolic pathways in the liver. The current study first time provides important clues and evidence for identifying the differentially expressed genes in livers due to Cr (VI)-induced liver injury in chickens. [ABSTRACT FROM AUTHOR]

Background: Divergent selection for meat and egg production in poultry has resulted in strains of birds differing widely in traits related to these products. Modern strains of meat birds can reach live weights of 2 kg in 35 d, while layer strains are now capable of producing more than 300 eggs per annum but grow slowly. In this study, RNA-Seq was used to investigate hepatic gene expression between three groups of birds with large differences in growth potential; meat bird, layer strain as well as an F1 layer x meat bird. The objective was to identify differentially expressed (DE) genes between all three strains to elucidate biological factors underpinning variations in growth performance. Results: RNA-Seq analysis was carried out on total RNA extracted from the liver of meat bird (n = 6), F1 layer x meat bird cross (n = 6) and layer strain (n = 6), males. Differential expression of genes were considered significant at P < 0.05, and a false discovery rate of < 0.05, with any fold change considered. In total, 6278 genes were found to be DE with 5832 DE between meat birds and layers (19%), 2935 DE between meat birds and the cross (9.6%) and 493 DE between the cross and layers (1.6%). Comparisons between the three groups identified 155 significant DE genes. Gene ontology (GO) enrichment and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis of the 155 DE genes showed the FoxO signalling pathway was most enriched (P = 0.001), including genes related to cell cycle regulation and insulin signalling. Significant GO terms included 'positive regulation of glucose import' and 'cellular response to oxidative stress', which is also consistent with FoxOs regulation of glucose metabolism. There were high correlations between FoxO pathway genes and bodyweight, as well as genes related to glycolysis and bodyweight. Conclusions: This study revealed large transcriptome differences between meat and layer birds. There was significant evidence implicating the FoxO signalling pathway (via cell cycle regulation and altered metabolism) as an active driver of growth variations in chicken. Functional analysis of the FoxO genes is required to understand how they regulate growth and egg production. [ABSTRACT FROM AUTHOR]

Gangrenous dermatitis (GD) is a disease of chickens and turkeys that causes severe economic losses in the poultry industry worldwide. Clostridium septicum, Clostridium perfringens type A, and occasionally Clostridium sordellii are considered the main causes of GD, although Staphylococcus aureus and other aerobic bacteria may also be involved in some cases of the disease. GD has become one of the most significant diseases of commercial turkeys in the United States. Several infectious and/or environmental immunosuppressive factors can predispose to GD. Skin lesions are considered to be the main portal of entry of the microorganism(s) involved. GD is characterized by acute onset of mortality associated with gross skin and subcutaneous tissue lesions consisting of variable amounts of serosanguineous exudate together with emphysema and hemorrhages. The underlying skeletal muscle can also be involved. Ulceration of the epidermis may be also noticed in cases complicated with S. aureus. Microscopically, necrosis of the epidermis and dermis, and subcutaneous edema and emphysema are commonly observed. Gram-positive rods can be identified within the subcutis and skeletal muscles, usually associated with minimal inflammatory infiltrate. A presumptive diagnosis of GD can be made based on history, clinical signs, and gross anatomic and microscopic lesions. However, confirmation should be based on demonstration of the causative agents by culture, PCR, immunohistochemistry, and/or fluorescent antibody tests. [ABSTRACT FROM AUTHOR]

Selection for cold tolerance in chickens is important for improving production performance and animal welfare. The identification of chicken breeds with higher cold tolerance and production performance will help to target candidates for the selection. The thyroid gland plays important roles in thermal adaptation, and its function is influenced by breed differences and transcriptional plasticity, both of which remain largely unknown in the chicken thyroid transcriptome. In this study, we subjected Bashang Long-tail (BS) and Rhode Island Red (RIR) chickens to either cold or warm environments for 21 weeks and investigated egg production performance, body weight changes, serum thyroid hormone concentrations, and thyroid gland transcriptome profiles. RIR chickens had higher egg production than BS chickens under warm conditions, but BS chickens produced more eggs than RIRs under cold conditions. Furthermore, BS chickens showed stable body weight gain under cold conditions while RIRs did not. These results suggested that BS breed is a preferable candidate for cold-tolerance selection and that the cold adaptability of RIRs should be improved in the future. BS chickens had higher serum thyroid hormone concentrations than RIRs under both environments. RNA-Seq generated 344.3 million paired-end reads from 16 sequencing libraries, and about 90% of the processed reads were concordantly mapped to the chicken reference genome. Differential expression analysis identified 46–1,211 genes in the respective comparisons. With regard to breed differences in the thyroid transcriptome, BS chickens showed higher cell replication and development, and immune response-related activity, while RIR chickens showed higher carbohydrate and protein metabolism activity. The cold environment reduced breed differences in the thyroid transcriptome compared with the warm environment. Transcriptional plasticity analysis revealed different adaptive responses in BS and RIR chickens to cope with the cold, and showed higher responsiveness in BS compared with RIR chickens, suggesting greater adaptability of the thyroid in BS chickens. Moreover, 10,053 differential splicing events were revealed among the groups, with RNA splicing and processing, gene expression, transport, and metabolism being the main affected biological processes, identifying a valuable alternative splicing repertoire for the chicken thyroid. A short isoform of TPO (encoding thyroid peroxidase) containing multiple open reading frames was generated in both breeds by skipping exons 4 and 5 in the cold environment. These findings provide novel clues for future studies of the molecular mechanisms underlying cold adaptation and/or acclimation in chickens. [ABSTRACT FROM AUTHOR]

Uric acid (UA) is a potent scavenger of oxidants in most mammalian and avian species. The aim of this study was to obtain more comprehensive information regarding the relationship between different concentrations of UA and oxidative balance in chicken cardiac cells. First, oxidative damage parameters were measured in chicken cardiac cells treated with different concentrations of UA. UA concentrations within the normal physiological range had no effect, while treatment with a high level of UA, i.e. 1200 μM, increased the malondialdehyde (MDA) and protein carbonyl contents, decreased the superoxide dismutase (SOD) and catalase (CAT) activities, and had no effect on glutathione (GSH) in cardiac muscle cells. In addition, the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway was stimulated in cells treated with 1200 μM UA. Next, the role of UA in protecting cells from oxidative damage was investigated in hydrogen peroxide (H2O2)-damaged chicken cardiac cells. Treatment with UA within the normal physiological range reduced the increased MDA and protein carbonyl contents and SOD enzymatic activity induced by H2O2 exposure to some extent and inhibited reactive oxygen species (ROS) formation, presumably as a result of the Nrf2 pathway activation in H2O2-damaged cells. By contrast, the MDA and protein carbonyl contents were increased, SOD enzymatic activity was depressed, and the Nrf2 pathway was further down-regulated in H2O2-damaged cells treated with 1200 μM UA. In conclusion, the results indicated that physiological UA concentration partially alleviated oxidative stress in chicken cardiac muscle cells treated with H2O2. However, supraphysiological UA concentrations promoted oxidative damages directly in primary cultured chicken cardiac muscle cells and aggravated oxidative stress in H2O2-damaged cells. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyse the microscopic and ultrastructural lesions of the livers of broiler chickens during fattening. Three genetic lines of broiler chickens (Ross 308, Cobb 500, Hubbard F15) were investigated. The liver samples were taken on the 3rd, 10th, 17th, 24th, 31st, and 38th day of life from six healthy broiler chickens from each commercial broiler flock. The dominant microscopic lesions were associated with prolonged hypoxia and bile ductules, including: fatty, vacuolar and parenchymatous degeneration, necrosis of epithelial cells of bile ductules, necrosis of hepatocytes around the proliferating bile ductules, lymphoid cell infiltration around the bile ductules and blood vessels, proliferation of the bile ductules, proliferation of the connective tissue around bile ductules and stimulation of the lymph nodules. Ultrastructural evaluation revealed abnormalities involving mitochondria and rough endoplasmic reticulum. The mitochondria underwent swelling, polymorphism, proliferation and damage. The rough endoplasmic reticulum underwent defragmentation and acinar transformation. The cytoplasm of most hepatocytes showed vacuoles of varying size or lipid droplets and the presence of cytoplasmic myelin-like structures. This study shows that the livers of broiler chickens are the most predisposed to the occurrence of lesions on the 17th, 31st and 38th days of life. [ABSTRACT FROM AUTHOR]

We attempted to determine the growth characteristics of cultured lung fibroblasts of layer type chickens and to investigate presence of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in these cells in vitro. Lung fibroblasts were isolated, characterized and subcultured from one-day-old layer type chicken lungs. Two different methods, explant culture and enzymatic techniques, were used for culturing and the results were compared. The presence of MMP-2 and TIMP-1 was shown in cultured fibroblasts by immunocytochemical staining, immune blotting and zymography methods. Immune expressions of neither MMP-9 nor TIMP-2 enzymes could be detected. [ABSTRACT FROM AUTHOR]

1. The effects of acute heat stress (2&ThickSpace;h at 32°C and 75% RH) on body temperature and indices of respiratory thermoregulation and skeletal muscle function were examined in two divergently selected male grandparent lines of broiler and layer-type chickens at two ages (35 and 63&ThickSpace;d), or at a similar body weight (&nvsim;2·2&ThickSpace;kg). 2. The two chicken lines exhibited markedly different baseline blood acid–base and skeletal muscle characteristics. At the same age or live weight, birds from the broiler line had significantly higher venous blood carbon dioxide tensions associated with lower blood pH. Plasma creatine kinase (CK) activities reflecting muscle membrane damage were also greatly elevated in the broiler line. 3. Exposure to acute heat stress caused an increase in deep body temperature, panting-induced acid–base disturbances and elevated plasma CK activity in both lines of chicken, an effect that increased with age. The extent of disturbances in acid–base regulation and heat-stress-induced myopathy were more pronounced in the broiler than the layer line at the same age or similar live weights. 4. It is suggested that genetic selection for high muscle growth in broiler lines has compromised their capacity to respond to an acute thermal challenge, leading to detrimental consequences for muscle function. This reduction in heat tolerance may have important implications for bird welfare and subsequent meat quality. [ABSTRACT FROM AUTHOR]

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1. Genetic parameters for the sudden death syndrome (SDS) were estimated in meat-type chickens. Data were collected over 11 generations of selection for body weight within two distinct breeds (Cornish and White Rock).2. The animal model was used exclusively with linear methods (LM) to estimate genetic parameters. Heritability (h 2 ) of SDS on the liability scale was 0&CenterDot;30?&PlusMinus;?0&CenterDot;002 and 0&CenterDot;25?&PlusMinus;?0&CenterDot;002 in the Cornish and White Rock breeds, respectively.3. A positive genetic correlation (rg) with ascites (AS) was determined (~0&CenterDot;3?&PlusMinus;?0&CenterDot;006). However, it was not possible to estimate the rg of SDS with body weight because of the low prevalence of the defect trait studied (1&CenterDot;8% in the Cornish and 1&CenterDot;5% in the White Rock).4. Heritability of SDS calculated using male records only was 0&CenterDot;45?&PlusMinus;?0&CenterDot;009 and 0&CenterDot;35?&PlusMinus;?0&CenterDot;009, and rg with body weight was 0&CenterDot;30?&PlusMinus;?0&CenterDot;010 and 0&CenterDot;27?&PlusMinus;?0&CenterDot;009, in the Cornish and White Rock breeds, respectively.5. In conclusion, the heart defect investigated was heritable with a positive genetic correlation with AS and body weight. [ABSTRACT FROM AUTHOR]

1. Pulmonary hypertension syndrome followed by ascites is a metabolic disorder in broilers that occurs more often in fast-growing birds and at cool temperatures.2. Knowledge of the genetic relationships among ascites-related traits and performance traits like carcase traits or feed efficiency traits is required to design breeding programmes that aim to improve the degree of resistance to ascites syndrome as well as production traits. The objective of this study was to estimate these genetic correlations.3. Three different experiments were set up to measure ascites-related traits (4202 birds), feed efficiency traits (2166 birds) and carcase traits (2036 birds). The birds in different experiments originated from the same group of parents, which enabled the estimation of genetic correlations among different traits.4. The genetic correlation of body weight (BW) measured under normal conditions and in the carcase experiment with the ascites indicator trait of right ventricle to total ventricle ratio (RV:TV) measured under cold conditions was 0&CenterDot;30. The estimated genetic correlation indicated that single-trait selecting for BW leads to an increase in occurrence of the ascites syndrome but that there are realistic opportunities of multi-trait selection of birds for improved BW and resistance to ascites.5. Weak but positive genetic relationships were found between feed efficiency and ascites-related traits suggesting that more efficient birds tend to be slightly more susceptible to ascites.6. The relatively low genetic correlation between BW measured in the carcase or in the feed efficiency experiments and BW measured in the ascites experiment (0&CenterDot;49) showed considerable genotype by environment interaction. These results indicate that birds with high genetic potential for growth rate under normal temperature conditions have lower growth rate under cold-stress conditions due to ascites. [ABSTRACT FROM AUTHOR]

Revealing the multifocal mechanisms affecting cross-talk between Clostridium perfringens pathogenesis and the host response is an urgent need in the poultry industry. Herein, the activity of Cannabis sativa-derived cannabidiol (CBD) and selenium nanoparticles (Nano-Se) in modulating the host response to Clostridium perfringens challenge was investigated in broiler chickens subjected to a mild infection model. The infected chickens exhibited no clinical manifestations, confirming the potential hazard of pathogen transmission to the food chain in the commercial sector. However, both CBD and Nano-Se affected the responses of chickens to C. perfringens challenge. The beneficial actions of both agents were manifested in the upregulated expression of genes determining gut barrier function. Both CBD and Nano-Se promoted shifts in gut bacterial enzyme activity to increased energy uptake in challenged chickens and upregulated potential collagenase activity. There was no opposite effect of CBD and Nano-Se in mediating the host response to challenge, whereas an additive effect was evidenced on the upregulation of gene determining gut integrity. Collectively, these findings indicate that understanding the action mechanisms of CBD and Nano-Se is of great interest for developing a preventive strategy for C. perfringens infection in broilers. [ABSTRACT FROM AUTHOR]

Background: Poultry breeding programs have been focused on improvement of growth and carcass traits, however, this has resulted in correlated changes in internal organ weights and increased incidence of metabolic disorders. These disorders can affect feed efficiency or even cause death. We used a high density SNP array (600 K, Affymetrix) to estimate genomic heritability, perform genome-wide association analysis, and identify genomic regions and positional candidate genes (PCGs) associated with internal organ traits in an F2 chicken population. We integrated knowledge of haplotype blocks, selection signature regions and sequencing data to refine the list of PCGs. Results: Estimated genomic heritability for internal organ traits in chickens ranged from low (LUNGWT, 0.06) to high (GIZZWT, 0.45). A total of 20 unique 1 Mb windows identified on GGA1, 2, 4, 7, 12, 15, 18, 19, 21, 27 and 28 were significantly associated with intestine length, and weights or percentages of liver, gizzard or lungs. Within these windows, 14 PCGs were identified based on their biological functions: TNFSF11, GTF2F2, SPERT, KCTD4, HTR2A, RB1, PCDH7, LCORL, LDB2, NR4A2, GPD2, PTPN11, ITGB4 and SLC6A4. From those genes, two were located within haplotype blocks and three overlapped with selection signature regions. A total of 13,748 annotated sequence SNPs were in the 14 PCGs, including 156 SNPs in coding regions (124 synonymous, 26 non-synonymous, and 6 splice variants). Seven deleterious SNPs were identified in TNFSF11, NR4A2 or ITGB4 genes. Conclusions: The results from this study provide novel insights to understand the genetic architecture of internal organ traits in chickens. The QTL detection performed using a high density SNP array covered the whole genome allowing the discovery of novel QTL associated with organ traits. We identified PCGs within the QTL involved in biological processes that may regulate internal organ growth and development. Potential functional genetic variations were identified generating crucial information that, after validation, might be used in poultry breeding programs to reduce the occurrence of metabolic disorders. [ABSTRACT FROM AUTHOR]