Influence of Ascites Syndrome on Growth Pattern of Chickens Reared at Normal or Cold Ambient Temperature

Ascites syndrome (AS) is a metabolic disorder usually seen in highly improved meat-type broiler strains. This syndrome causes major financial losses to the poultry industry. Previously it was believed that AS incidence was a side effect of intense selection for rapid growth rate (GR) or higher market weight. If this belief is the case, selection for further increase in GR will not be rational. However, it was later understood that there were significant genetic variations for both GR and susceptibility/resistance to AS; thus selective breeding could be helpful in diminishing the incidence of AS while improving GR. Furthermore, it was hypothesized that genes controlling the GR were not genetically dependent on those genes controlling susceptibility to AS. In the current research, we aimed to study the association of GR traits with AS% in a pure sire line. A total of 1458 1-day-old chicks from 67 sire families were used. The results revealed that ascitic chicks were not significantly superior in early GR traits (i.e. before day 28) than the healthy ones. At later ages, probably due to the commencement of the syndrome, the ascitic chicks were significantly lighter in body weight (BW) than their healthy counterparts. The lack of significant genetic correlations between the GR traits and AS% indicated that there was considerable scope for simultaneous selection of birds for increased BW and GR while controlling susceptibility to AS.