Optimum range of weight-age data for estimationof growth curve parameters in Korean native chicken

With emphasis on native genetic resource, Korean native chicken is one of the major native breeds in poultry in Korea. The weight-age data from 216 pullets of Korean native chicken were used to fit the growth curve using Gompertz model. Live weights have been recorded every three weeks for 36 weeks for 5 strains. All available weight data from birth to the 6 specific ages of week were used for the estimation of parameters. The variation in estimates of mature weight (A) decreased with the increase of age 21 through 36 weeks for all 5 strains studied. However, the variation of rate of maturing (k) showed a tendancy increase with the increase of age. These results indicate that the fitting of growth curve is getting more stable for asymptotic value (A) and more flexible for curve shape (k) with the increase of weight-age data range. Correlations among estimates of A and among estimates of k at various ages showed the highest range of 0.93 ~ 0.99 between 30 and 36 weeks except for the maturing rate (k) of red brown strains. The correlations between A and k tended to fluctuate and were not significant statistically at various ages. Thus, the estimates of growth curve parameters, A and k suitable for genetic studies in Korean native chicken can be derived from accumulated weight-age data after 30 weeks of age.