EN
The data were collected for 1978—1987 from breeding documents for all Simental and Red-White cows under milk control in the Krosno voivodship. It was found that a percent of heavy parturitions in Simental cows increased from 2.32% in 1978 to 5.43% in 1987 (mean 3.12%). Mortality of calves during the first months of life increased from 2.84% to 9.07% (mean 5.5%). In Red-White cows a mean percent of heavy calvings was 3.22% and newborn mortality was 7.23%. Developmental anomalies appeared rarely (0.024% in Simentals and 0.11% in Red-White cows). A mean body weight of newborn Simental calves was 32.09 kg and Red-White 29.32 kg. Simental cows calved for the first time at the age of 920 days (in private farms at 792 days) whereas Red-White calved for the first time at the age of 846 days. Percent of abortions decreased in Simental cows from 1.60% in 1978 to 0.85% in 1987 (mean 1.49). In Red-White cows this value was 1.64%. Interparturient period lasted in Simental cows for 296 days and in Red-White cows for 391 days. A non-return index (efficacy of the first insemination) for 10 years was 76.8% in Simental and 78.1% in Red-White cows and an insemination index was 1.30% and 1.28%, respectively.