Growth and development traits of female Brown Swiss and Holstein Friesian cattle born in the Research Farm of the Agricultural College at Atatürk University were estimated by the Richards growth model by using weight-age data obtained between 1987 and 1998. A, B, k and m parameters of the Richards model were 501 ± 6.88 kg, 0.6666 ± 0.0262, 0.0581 ± 0.0019/month and 4.07 ± 0.44 for Brown Swiss, and 496 ± 7.40, 0.8041 ± 0.032, 0.0515 ± 0.0028/month and 2.64 ± 0.67 for Holstein Friesian cattle. Estimated birth weight and periodic weights taken between birth and 3 years of age for both breeds were close to each other. The highest daily weight gains of both breeds were obtained between birth and 6 months of age. Brown Swiss and Holstein Friesian cattle attained 65% and 95% of their mature live weights at 22.9 and 67.8 months, and 22.5 and 64.7 months, respectively. First calving age and live weight at first calving were 34.4 ± 0.4-months and 392 ± 3.2 kg for Brown Swiss, and 31.6 ± 0.5 months and 377 ± 5.2 kg for Holstein Friesian cattle. While the effects of the first calving age on B, m (P < 0.01) and A (P < 0.05) were statistically significant, its effect on the k parameter was not significant. Effects of calving at intermittent and consecutive years on the growth parameters were not significant.

Growth and development traits of female Brown Swiss and Holstein Friesian cattle born in the Research Farm of the Agricultural College at Atatürk University were estimated by the Richards growth model by using weight-age data obtained between 1987 and 1998. A, B, k and m parameters of the Richards model were 501 ± 6.88 kg, 0.6666 ± 0.0262, 0.0581 ± 0.0019/month and 4.07 ± 0.44 for Brown Swiss, and 496 ± 7.40, 0.8041 ± 0.032, 0.0515 ± 0.0028/month and 2.64 ± 0.67 for Holstein Friesian cattle. Estimated birth weight and periodic weights taken between birth and 3 years of age for both breeds were close to each other. The highest daily weight gains of both breeds were obtained between birth and 6 months of age. Brown Swiss and Holstein Friesian cattle attained 65% and 95% of their mature live weights at 22.9 and 67.8 months, and 22.5 and 64.7 months, respectively. First calving age and live weight at first calving were 34.4 ± 0.4-months and 392 ± 3.2 kg for Brown Swiss, and 31.6 ± 0.5 months and 377 ± 5.2 kg for Holstein Friesian cattle. While the effects of the first calving age on B, m (P < 0.01) and A (P < 0.05) were statistically significant, its effect on the k parameter was not significant. Effects of calving at intermittent and consecutive years on the growth parameters were not significant.