The effect of successful phenotypic selection against ascites syndrome on different traits in a commercial broiler line

The aim of present study was to investigate the effect of selection against ascites syndrome on different traits body growth, internal organs, and bloodparameters in a broiler line. Therefore, by classifying different families based on the frequency of ascites under intense ascites inducing condition(AIC), 10 susceptible families (SUS) and 10 resistant families (RES) to ascites were selected and another set of offspring from the same families werebred under normal commercial condition (NCC). This process of selection and cross validation was carried out twice in the two distinct generations.The genetic relationship of different traits, the difference in the frequency of ascites between AIC and NCC, and the difference between different traitsin SUS and RES were performed by correlation statistics, Chi-square test, and GLM procedure of SAS software (version 9.1), respectively. Thecorrelation between ascites susceptibility in different families indicated that families that showed more ascites under AIC also had more ascites underNCC. Comparative study of different traits in susceptible and resistant groups showed that in SUS, body weight, growth rate and respiratory capacitywere significantly lower and blood partial pressure of carbon dioxide was significantly higher than RES (P<0.05). In the present study it was shownthat selection against this syndrome not only does not reduce growth rate in the investigated broiler line, but also improves growth traits and resistanceto this syndrome in the mentioned line.