PERFORMANCE OF FIRST-CALF DAIRY HEIFERS UNDER A LIMITED-SEASON EARLY-FRESHENING MANAGEMENT SYSTEM

Productive and reproductive performances of 371 dairy heifers of five breeds were evaluated. All females were served at first heat after attaining 13 months of age, but only if such service would result in due dates during mid-July to mid-January. Average first service age was 455 days; average age at freshening was 781 days. Significant positive relationships between age and weight at freshening, milk yield, fat yield, gestation length, and birth weight of calf were detected and were consistent with previous research. A slight positive relationship existed between age of freshening and days open during the first lactation. Although Holsteins had a consistently higher frequency of calving problems, it was not possible to detect differences in frequency due to age at parturition. Overall frequencies were: retained placenta, 2.4%; uterine prolapse, 1.1%; dystocia, 4.9%; metritis, 10.5%; dead calves, 10.2%; and one or more problems, 21.6%. Dairymen should expect no increase in problems at freshening if animals are managed according to standard recommendations and are bred at 13 months of age. © 1968, American Dairy Science Association. All rights reserved.