HERITABILITY OF ASCITES AND THE RATIO OF RIGHT TO TOTAL VENTRICLE WEIGHT IN BROILER BREEDER MALE LINES

The objectives of this study were to induce ascites in three pure male line populations by subjecting them to cold stress, and to calculate heritability estimates for ascites (ASCITES) and the ratio of right to total ventricle weight (RATIO) in these populations under cold stress. Data were collected during the winter of 1993 to 1994 from 3,436 cockerels representing three commercial broiler breeder male lines. The male lines used in this study were characterized by: rapid growth rate and good feed efficiency (RG), moderate growth, good conformation, and excellent livability (MG), and maximum white meat yield and rapid growth (YD). Birds were cold stressed and euthanatized at 8 wk of age. Ratios of right to total ventricle weight and ascites (birds with fluid in the abdominal cavity) were recorded on every bird. Line means for the incidence of ascites were 17.5, 18.7, and 33.5% for RG, MG, and YD, respectively. Lines RG and MG did not differ from each other for ascites, but both were less than YD (P <.05). Means and standard deviations for the ratio of right to total ventricle weight (RATIO) were .299 +/- .09, .297 +/- .08, and .294 +/- .09 for RG, MG, and YD, respectively. Line means for RATIO did not differ. Heritability estimates of RATIO were .21 +/- .09, .21 +/- .09, and .27 +/- .08 for RG, MG, and YD, respectively; and heritabilities of ascites were .36 +/- .10, .11 +/- .08, and .44 +/- .09, respectively. Phenotypic correlations of ASCITES with RATIO were .54, .43, and .50 in RG, MG, and YD and genetic correlations of ASCITES with RATIO were .69 +/- .13, .46 +/- .33, and .78 +/- .10 in RG, MG, and YD, respectively.