Selection indices for some economic traits in the two-breed cross hens
1993
Napaphan Poyasathira
Measurements of body weight at 20 wks. of age (BW), age at first egg (AFE), and egg production until 32 wks. of age (EP) on 813 progenies from 228 dams mated to 24 sires in the two-breed crosses of Shanghai and Rhode Island Red were used in this experiment. Sib analysis of variance and covariance were used to determine estimates of heritabilites (h** (2)), genetic, and phenotypic correlations for the primary traits. Estimates of variance and covariance components from the hierarchal (nested) analyses of variance and covariance were used to set the genetic and phenotypic variance-covariance matrices for overall population. The h** (2) values were 0.61+-0.17 for BW, 0.20+-0.16 for AFE, and 0.05+-0.15 for EP. The genetic correlations of BW-AFE, BW-EP, and AFE-EP were -0.14+-0.02, 0.29+-0.16, and -0.40+-0.04, respectively. The phenotypic correlations of BW-AFE, BW-EP, and AFE-EP were -0.30+-0.04, 0.08+-0.04, and -0.40+-0.04, respectively. The relative economic values of the primary traits obtained by farm price analyses were 92.3, -1, and 4.6 for BW, AFE, and EP, respectively. The estimates of these parameters were used to construct selection indices for BW, AFE, and EP. The index as the most effective linear combination of the primary traits was: 0.27 (BW)+1.58 (EP).
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