Glenda Heywood
I looked up the article on
Ascites
it is a disease of the heart in fast growing birds
NOT AT ALL WITH THE LIQUID ACCUMULAION IN THE HENS BODY
http://www.thepoultrysite.com/articles/500/understanding-and-controlling-ascites/
Factors that Trigger Pulmonary Hypertension and Ascites
Ascites mortality tends to be highest in the fastest growing flocks, and that incidence can be lowered by any strategy that slightly slows the overall flock growth rate. This slightly slower growth rate reduces the demand on the heart, pulmonary hypertension and ascites. The incidence of ascites increases whenever broilers are exposed to cool temperatures. Cool temperatures increase cardiac output since the bird’s metabolic rate must increase to meet the demand for body heat production. Exposing broilers to low oxygen immediately triggers an increase in pulmonary arterial pressure since the efficiency of respiratory process is reduced. When birds are chronically exposed to low oxygen levels, it tend to lead to a high incidence of ascites. The respiratory damage associated with disease, dust, or poor air quality can reduce respiratory efficiency. In addition, these conditions can partially obstruct the airways, reduce the number of vascular channels available for blood flow, thereby reducing blood oxygen, increasing pulmonary vascular resistance and pulmonary arterial pressure, and causing ascites in broilers.
Lowering the Odds of for Pulmonary Hypertension and Ascites
In contrast to the known triggers for ascites outlined above, the incidence of ascites can be lowered by any strategy that reduces the metabolic demand for oxygen and thus reduces cardiac output. Slightly restricting broiler growth rates and providing thermoneutral temperatures fall into this category. The incidence of ascites also can be reduced by treatments that reduce pulmonary vascular resistance by dilating the pulmonary vasculature. Although a number of chemical are capable of reducing pulmonary vascular resistance, none are approved for use in birds destined for human consumption. However, the amino acid arginine is utilized by cells lining the pulmonary blood vessels to facilitate pulmonary vascular dilation during high pressure and flow conditions. Our research has shown that adding supplemental arginine to broiler diets effectively reduces pulmonary vascular resistance and the incidence of ascites in broilers exposed to cool temperatures. Nonetheless, it is important to remember that increased use dietary arginine have been shown to influence lysine requirements.
Conclusion
Broilers susceptible to ascites are capable of outgrowing the capacity of their lungs to oxygenate blood. Factors that increase oxygen demand include: exposure to cool temperatures, low oxygen levels, and respiratory damage associate with disease, dust or poor air quality. Pulmonary hypertension and ascites in modern broiler strains may be reduced by any strategy that reduces the metabolic demand for oxygen and thus reduces cardiac output. Slight restrictions in broiler growth and providing a thermoneutral environment are two strategies that work.
Further Information
This article was largely abstracted from a 1999 Hubbard Farms Technical Report by R. F. Wideman (“Understanding pulmonary hypertension syndrome (ascites)”). This article is published with the permission of the author and Hubbard Farms.
