Strategies to alleviate the incidence of ascites in broilers: a review

Abstract

Ascites is a complex problem caused by many interacting factors such as genetics, environment and management. Many nutritional, medicinal and management strategies have been proposed to alleviate the problem. Higher levels of dietary vitamin C and E along with selenium yeast might be beneficial, presumably because of their role in improving cellular integrity. Oils rich in n-3 fatty acids have been shown to reduce pulmonary hypertension and, consequently, ascites incidence. The potential use of flax oil has already been demonstrated, whereas the effects of other oils rich in n-3 fatty acids (fish, linseed and canola oils) remain to be investigated. The assessment of the effects of dietary electrolyte balance on ascites incidence seems to be a promising field of research in broiler nutrition. In general, reducing the dietary level of salt (NaCl) and adding bicarbonates to the diet and drinking water have been proposed as potential "cost-effective" methods to reduce ascites incidence. The use of nutrients/drug agents that increase the vascular capacity of the lungs or decrease the pulmonary vascular resistance may help to alleviate the problem, but economic and local feed regulations might restrict such use. Diuretics have also shown positive effects, presumably because there is a reduction of sodium and fluid retention in the body; litter humidity however must be closely monitored if diuretics are continuously administered. As the high metabolic rate (fast growth) is a major factor contributing to the susceptibility of broilers to ascites, early-age feed or nutrient restriction (qualitative or quantitative) or light restriction in order to slow down the growth rate seem practically viable methods, since final body weight is not compromised. Optimization of the house temperature and ventilation in cold weather seem helpful practices to decrease ascites incidence. Under practical conditions, it might be interesting to test the additive effects of different approaches when used in combination.