ABSTRACT
Records of 234 lactations from F1 Holstein x Gyr daughters of proven bulls were used in this study for the evaluation of productive and reproductive characteristics of cows. Data were collected from a private farm located in the municipality of Santo Antônio do Monte, MG, Brazil. The objective of this study was to evaluate the effects of Holstein bull's PTA milk (predicted transmitting ability) calving year, season, and parity on the productive and reproductive characteristics of F! cows. The productive characteristics analyzed were total milk production (TMP), average daily production (ADP), days in milk (DIM), and milk yield per day of calving interval (MYDCI). The studied reproductive characteristics were service interval (SI), calving interval (CI), and gestation length (GL). The results were subjected to statistical analysis and means for significant effects were compared using Duncan's test at a significance level of 5%. F1 animals efficiently expressed their genetic potential for milk production with an average total milk production of 7842.61 kg and average daily production of 24.53 kg. Means for days in milk, milk yield per day of calving interval, service interval, calving interval, and gestation length were 322.52 days, 20.73 kg, 106.0 days, 383.23 days, and 276.18 days, respectively. Properly managed F1 Holstein x Gyr daughters of proven bulls fed a balanced diet efficiently expressed their genetic potential for milk production without adverse effects on reproduction. Moreover, Holstein x Gyr cows should be selected based on parents' PTA for milk traits and other factors such as environmental conditions and management.
