CORRELATIONS AMONGST TRAITS OF ECONOMIC IMPORTANCE IN LAYER TYPE CHICKENS UNDER RECIPROCAL RECURRENT SELECTION

The objective of this study was to estimate genetic and phenotypic correlations amongst traits in layer type chickens under reciprocal recurrent selection. Matings within pure male line and female lines were carried out to produce purebred male line (AA x AA) and female line (BB x BB). A total of 364 pullets arising from 207 hens and 23 cocks in generation 1 and 440 pullets from 70 hens and 10 cocks in generation 2 under selection were monitored in individual cage units for part period egg production up to 280 days. Parameters considered were age at sexual maturity (ASM), body weight at 20 and 40 weeks (BW 20 and BW40), egg weight average (EWTAV) and egg production up to 280 days (Egg 280). Results obtained shows that ASM had a high negative genetic (-0.52 to -0.64) and moderate phenotypic (-0.39 to -0,46) correlations with BW20 in the male line, positive genetic and phenotypic correlations with EWTAV in both male (0.41 to 0.80 and 0.07 to 0.26) and female line (0.53 and 0.09 to 0.14) and negative genetic and phenotypic correlations in both male (0.45 to -0.65 and -0.08 to -0.53) and female (-0.37 and -0.20), lines, respectively. Similarly, BW40 had positive genetic and phenotypic correlations (0.68 to 0.93 and 0.01 to 0.20) with Egg-280 in the female line. EWTAV had a negative genetic and phenotypic correlation with Egg280 in both male (-0.53 to -0.96 and -0.09 to -0.17) and female line (-0.15 to -0.27 and -0.09 to -0.15), respectively. It was concluded that the favourable correlations that exist between traits measured in this study for both male and female lines indicate the presence of non-additive genetic effects which can be utilized through selection and crossing for commercial use.