Ascites Formation in the Chicken

Oláh, Imré; Taylor, Robert L.; Glick, Bruce

doi:10.3382/ps.0622095

Cited by 10 publications

(1 citation statement)

References 6 publications

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“…It is more likely that the physiologic changes associated with PH-induced hypoxia in the lung favour the development and retention of nodules that would have been removed in normal birds (Julian et al, 1989a). The ascites resulting from intravenous injection of carbon suspension reported by Olah et al (1983) was probably caused by acute PH arising from obstruction of blood capillaries, since capillaries were blocked by carbon particles when this technique was used to produce ascites (Julian, unpublished).…”

Section: Reduced Vascular Capacitymentioning

confidence: 99%

Ascites in poultry

1993

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SUMMARYResearch on ascites occurring in meat-type chickens reared at moderate and low altitude has shown that the pathogenesis is similar to that of the high altitude disease. Pulmonary hypertension (PH) caused by increased blood flow or increased resistance to flow in the lung results in right ventricular hypertrophy (RVH), valvular insufficiency, increased venous pressure and ascites. The structure of the avian heart, with its thin-walled right ventricle and muscular right atrioventricular valve, allows PH to induce heart failure quickly. The sudden increase in pulmonary hypertension syndrome (PHS) in meat-type chickens in the 1980s was associated with a rapid increase in growth rate and feed conversion. This was a result of a combination of genetic selection for fast-growing, heavy broilers with low feed conversion and a more dense, high caloric, pelleted food that supplied all the nutrients required for rapid growth and encouraged a high nutrient intake. PHS in meat-type chickens is usually primary pulmonary hypertension, that is, PH that occurs without evidence of prior heart or lung disease that could account for the increase in blood flow or resistance to flow that results in the increased pressure in the pulmonary arteries. The lungs of birds are firm and fixed in the thoracic cavity and they do not expand to draw air into the lung. The blood and air capillaries form a rigid network that allows only minimal expansion of the blood capillaries when more blood flow is required. Air is moved through the lung by abdominal movement which draws air in and out of the air sacs. The anatomy and physiology of the avian respiratory system are important in the susceptibility of meat-type chickens to PHS. The small stature of the modern meat-type chicken, the large, heavy breast mass, the pressure from abdominal contents on air sacs, and the small lung volume compared to body weight, may all be involved in the increased incidence of PHS. There is limited space for blood flow in the avian lung. Factors that increase blood flow or increase resistance to flow are additive. Increased blood viscosity caused by the polycythaemia of hypoxia, or increased erythrocyte rigidity of high Na + , are more likely to produce PH in fast-growing than in slow-growing birds. Increased flow due to cold exposure is also additive. Ascites caused by PH is a production-related disease at low altitude. It can be prevented easily by restricting growth rate. It is possible that some meat-type chickens of the phenotype we have created have reached the limit of blood flow through their lungs and that future improvements in growth rate will only be possible if the lung and abdominal cavity capacities are enlarged.

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Section: Reduced Vascular Capacitymentioning

confidence: 99%

Ascites in poultry

1993

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Poultry genetics and breeding

Athrey

2020

Animal Agriculture

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The influence of whole grain inclusion in pelleted broiler diets on proventricular dilatation and ascites mortality

Taylor

Jones

2004

British Poultry Science

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1. Pelleted diets, incorporating whole or ground wheat or barley in the pellets, were fed to broiler chickens and proventricular dilatation, digesta characteristics and mortality were recorded. 2. The incidence of proventricular dilatation was reduced when whole grain was incorporated into pelleted diets at 200 g/kg. 3. Enzyme application did not influence proventricular dilatation. 4. Digesta contents of intestinal sections were greater and pH lower in anterior intestinal sections when birds had dilated proventriculi. 5. Consideration of overall ascites mortality suggests that the incidence of the condition may be curtailed by whole grain inclusion in pelleted diets. 6. Production efficiency may be enhanced with whole grain inclusion in pellets when feed processing costs and flock health responses are considered.

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Ascites Formation in the Chicken

Cited by 10 publications

References 6 publications

Ascites in poultry

Ascites in poultry

Poultry genetics and breeding

The influence of whole grain inclusion in pelleted broiler diets on proventricular dilatation and ascites mortality

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