Evaluation of genetic parameters in a synthetic broiler chicken flock due to selection for high six week body weight

Data on 4060 chicks progeny of 44 sires and 264 dams were utilized for estimation of genetic and phenotypic parameters and subsequent construction of selection index for males and females separately. The heritability estimates from sire, dam and “sire+dam” components of variance were ranged from 0.110±0.061 to 0.448±0.088, 0.124±0.058 to 0.312±0.077, 0.437±0.133 to 0.533±0.093, 0.190±0.068 to 0.285±0.057, 0.271±0.1 05 to 0.688±0.108 and 0.212±0.084 to 0.473±0.091 for body weights at day old, fourweeks of age and six weeks of age, six week's breast angle, shank length and keel length, respectively in male chicks. The corresponding figures in females were 0.162±0.043 to 0.213±0.083, 0.130±0.061 to 0.232±0.085, 0.376±0.074 to 0.509±0.096, 0.171±0.074 to 0.251±0.096, 0.113±0.076 to 0.589±0.122 and 0.124±0.092 to 0.282±0.085 for body weights at day old age, four weeks of age and six weeks of age, six week's breast angle, shank length and keel length, respectively. The genetic correlations of six week body weight with each of the other traits were positive and high. The phenotypic (significant) and environmental correlations were high in all cases except with day old weight. The index coefficient for body weight, breast angle and shank length were 0.569, -8.417 and -28. 149 in males and 1.125, 14.733 and -171.722 in females, respectively. The efficiency of index was 0.73 for males and 1.00 for females: The expected genetic progress were 124.767g, 0.083° and 0.678 cm in males and 75.439g, 4.425° and 0.224 cm in females for six week's body weight, breast angle and shank length, respectively.