Análisis genético de características reproductivas de vacas Holstein criadas en un ambiente subtropical

genetic analysis of fertility traits of holstein cows reared in a subtropical environment. the objective of this work was to estimate the heritability and repeatability of reproductive traits of holstein cows reared in subtropical conditions. records from 171 cows were analyzed, which were daughters of 67 sires and 100 dams. the cows were born from 1986 to 2006, in las margaritas research station from the instituto nacional de investigaciones forestales, agrícolas y pecuarias (inifap), in hueytamalco, puebla, mexico. genetic parameters were estimated for interval from calving to first registered heat, interval from calving to first registered service, number of services per conception, days open, and calving interval. variance components for interval from calving to first registered heat, interval from calving to first registered service, days open, and calving interval were estimated with a single-trait repeatability animal model, while variance components for number of services per conception were estimated with a single-trait animal model, which included the direct additive genetic effect as a random effect. variance components were estimated with derivativefree restricted maximum likelihood using the mtdfreml program. estimates of heritability were low, from 0,01 (days open) to 0.13 (calving interval). estimates of repeatability were also low, ranging from 0.11 (interval from calving to first registered service) to 0.16 (days open). in general, estimates of heritability and repeatability obtained are within the interval of estimates reported in the scientific literature. estimates of genetic parameters indicate that direct response to one-trait selection would be slow.