Lack of Association of Ascites Incidence with Growth Characteristics in a Commercial Chicken Strain

Ascites syndrome, as one of the most common metabolic disorders in fast growing broiler chickens, has received considerable critical attention. Understanding the complexity and key factors in occurrence of ascites is vitally important for control of economic losses. Specifically, the hypothesis that will be tested is that higher ascites incidence can be observed in fast growing commercial strains. To confirm this hypothesis, the overall goal of this report was to pursue and compare growth measurements between two groups of birds: a healthy (control) group reared under standard breeding conditions and an ascites syndrome group reared under ascites inducing conditions. Two populations of broilers were used and differences between male and female broilers were recorded. For this purpose, growth characteristics data were collected from seven body weights between the ages of one and 42 days and nine growth rate parameters were studied in two populations that originated from 47 and 71 paternal half-sib families of meat-type sire chicken line. Statistical analyses for association study and estimating the heritability for particular traits were performed according to appropriate models using SAS, WOMBAT and Thrgibbs1F90 software. Our results showed no statistically significant difference in body weight and growth rate traits between healthy and ascitic broilers (P 0.05). Moreover, the results demonstrated moderate to high heritability (0.19 to 0.62) for ascites indicator traits (AITs). This finding highlights that selection for AITs may genetically improve resistance to ascites in this investigated chicken line. A further novel finding is that there were no consistent direct genetic correlations between AITs and growth traits (GTs). This evidence provides the opportunity to grow birds to heavier live bodyweight because high growth rate and body weight are not the main cause of susceptibility to ascites syndrome.