Abstract

The reproductive performance of dairy herds can be monitored by various indicators. The most common are based on time intervals, such as the calving interval and days open, or various rates, such as the 100-day InCalf-rate. However, most indicators do not consider the different strategies applied at farm level, e.g. the herd’s voluntary waiting period (VWP). The VWP has been shown to vary considerably between herds, and the variation is likely to continue to increase. Many common reproductive performance indicators are thus not accurately representing the true reproductive performance and this bias may be increasing. The aim of this study was to evaluate a new reproductive performance indicator: the percentage of cows that are pregnant after the herd voluntary waiting period plus 30 days (PPVWP+30). Data representing herds with different reproductive status was simulated using SimHerd, a dynamic, stochastic simulation model. A total of 18 different scenarios were simulated by altering reproductive management efficiency and biological reproductive status of the herd. Logistic regression models, together with receiver operating characteristics (ROC), were used to examine how well the reproductive performance indicator discriminated between which of two levels of management efficiency or biological status a herd belonged to. PPVWP+30 showed a diagnostic sensitivity (DSe) of 0.82 and a diagnostic specificity (DSp) of 0.87 in the analysis of management efficiency, and an area-under-curve (AUC) in the ROC analysis of 0.90. Corresponding results in the analysis of biological status were DSe = 0.70, DSp = 0.66, and AUC = 0.75. PPVWP+30 was compared to several other common indicators and was evaluated as the single best reproductive performance indicator considering both management efficiency and biological status, ease of use, and preparedness for differences in management and future changes in management

Published in

Book title: Book of proceedings : 14th International conference on production diseases in farm animals (ICPD)
ISBN: 9789058642264
Publisher: University Press

Conference

14th International conference on production diseases in farm animals (ICPD)

Authors' information