Bronchodilator, oxygen level, and temperature effects on ascites incidence in broiler chickens

Oxygen level, ambient temperature, and bronchodilator (metaproterenol) effects on performance, ascites incidence, and hematology were investigated using commercial broilers. In Experiment 1, two atmospheric oxygen concentrations (17.6, 20.6%) and two ambient temperatures (26.7, 32.2 C) were examined in a factorial arrangement. The low-oxygen (17.6%), ambient temperature combination (26.7 C) reduced (P < .01) weight gain whereas the high-oxygen ambient temperature combination enhanced (P < .05) such performance. Ascites incidence for chicks housed at 32.2 C was higher (P < .01) for birds maintained at 17.6% oxygen but oxygen concentration did not impact ascites incidence at 26.7 C. White blood cell counts were elevated in the low-oxygen (17.6%) group at both 26.7 and 32.2 C, and hematocrit was positively (R = .84; P < .05) correlated with ascites incidence. In Experiment 2, two oxygen levels (17.6, 20.6%) at constant 26.7 C were examined with and without metaproterenol, a bronchodilator. Metaproterenol reduced (P < .01) ascites incidence at 17.6% oxygen and completely prevented ascites at 20.6% oxygen. The data suggest that therapeutic development may be enhanced by using hematocrit as an indices of ascites and further that studies directed at bronchodilation have potential to alleviate ascites.