Body weight, feed-particle size, and ascites incidence revisited

Ascites, a specific type of congestive heart failure also known as Pulmonary hypertension syndrome, has been associated with BW and growth rate in broiler chickens. This association appears to be caused by the presence of ascites-susceptible broilers in commercial flocks, which develop pulmonary hypertension when challenged with either conditions that reduce oxygen availability or conditions that increase metabolic oxygen demand. It has been reported that genetic selection is Currently being applied to eliminate ascites-susceptible birds from the genetic pool of broiler breeders. Therefore, it is desirable to have current information on the incidence of ascites in today's commercial broilers reared under normal conditions. This would provide producers with information to decide whether to implement procedures to control the incidence of ascites in their flocks. Results from the present study indicate that ascites-related mortality remains associated with BW and growth rate in commercial broilers. From 2 strains of broilers studied, the strain that achieved greater BW and daily BW gains also had greater ascites-related mortality, accounting for nearly 50% of the total mortality when reared to 42 d of age. Providing pelleted feed vs. crumbles also increased ascites-related mortality, in conjunction with improved FCR, BW, feed intake, and growth rate. These results suggest that broilers susceptible to ascites are still present in commercial broiler flocks and that procedures for improving growth rate, Such as providing pelleted feed, cause these Susceptible broilers to develop the disease and increase ascites-related mortality in commercial settings.