Production and reproductive responses to use of DairyMAN: a management information system for New Zealand dairy herds.

To assess the benefits of on-farm use of a computerized management information system (DairyMAN, Department of Veterinary Clinical Science, Massey University, Palmerston North, New Zealand) on seasonally calving herds of New Zealand, data for 144 herds using this system were compared with a stratified random sample of 294 herds using only the centralized National Dairy Database system during the season 1993 to 1994. Demographic, reproductive performance, and milk yield indices were compared. Herds using DairyMAN had superior reproductive outcomes, measured as a higher percentage (+8.4%) of cows calving during the desired seasonal period (critical in this seasonal system) and a higher percentage of cows (+9.7%) mated at the optimal time to achieve a concentrated calving in the following year. Multiple analysis of covariance was used to differentiate effects. The superior performance was not associated with differences in some of the more commonly used reproductive indices (efficiency of estrus detection, first service nonreturn rate, and pregnancy rate), but the data used in the study do not accurately reflect true performance. Herds using DairyMAN had more information on breeding performance because pregnancy data were available and natural breedings were recorded for a longer period. With cows of equivalent genetic merit, herds using DairyMAN produced more milk (+1.2 L/d per cow) indicating that users achieved better management of the herd through improved attention to managerial details. This improved production was associated with the adoption of DairyMAN but is not shown by this study to be a direct consequence of it. DairyMAN user herds were larger (245 cows) than were herds not using the system (181 cows), but this difference did not significantly affect the various outcomes measured.