Broiler ascites: a review of the ascites

Broiler ascites, first seen in the form of a high altitude disease, has increased in importance world-wide in direct proportion to the improvement in growth performance of modern broilers. At the same time, the incidence has spread gradually from high altitude (above 2000 m) down to sea level, which gave rise to proposals of alternative causes including infections, toxins and metabolic disorders. Our work centred on anatomical and physiological aspects and included hypoxia models, chemotherapy and selection for genetic resistance. The latter led to the development of ascites-resistant lines, which allowed resistant stock to become commercially available in South Africa. The closure of the Poultry Section of the Onderstepoort Veterinary Institute brought ongoing ascites research to an abrupt end and some of the completed work was never published. This review of completed, ongoing and planned ascites work was at the time compiled as final report to the Director of the Institute in 1990. It came to light again recently and has been edited for publication. It also includes a new hypothesis on the reasons for the susceptibility of the domestic fowl and particularly broilers to hypoxic ascites.