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Logo of actavetsBioMed CentralBiomed Central Web Sitesearchsubmit a manuscriptregisterthis articleActa Veterinaria Scandinavica
 
Acta Vet Scand. 2012; 54(1): 5.
Published online Jan 30, 2012. doi:  10.1186/1751-0147-54-5
PMCID: PMC3298488
Evaluation of two dairy herd reproductive performance indicators that are adjusted for voluntary waiting period
Emma Löf,corresponding author1,2 Hans Gustafsson,2,3 and Ulf Emanuelson1
1Department of Clinical Sciences, Division of Ruminant Medicine and Veterinary Epidemiology, Swedish University of Agricultural Sciences. P.O. Box 7054, SE-750 07 Uppsala, Sweden
2Swedish Dairy Association, P.O. Box 210, SE-101 24 Stockholm, Sweden
3Department of Clinical Sciences, Division of Reproduction, Swedish University of Agricultural Sciences, P.O. Box 7054, SE-750 07 Uppsala, Sweden
corresponding authorCorresponding author.
Emma Löf: emma.lof/at/slu.se; Hans Gustafsson: hans.gustafsson/at/svenskmjolk.se; Ulf Emanuelson: ulf.emanuelson/at/slu.se
Received October 18, 2011; Accepted January 30, 2012.
Abstract
Background
Overall reproductive performance of dairy herds is monitored by various indicators. Most of them do not consider all eligible animals and do not consider different management strategies at farm level. This problem can be alleviated by measuring the proportion of pregnant cows by specific intervals after their calving date or after a fixed time period, such as the voluntary waiting period. The aim of this study was to evaluate two reproductive performance indicators that consider the voluntary waiting period at the herd. The two indicators were: percentage of pregnant cows in the herd after the voluntary waiting period plus 30 days (PV30) and percentage of inseminated cows in the herd after the voluntary waiting period plus 30 days (IV30). We wanted to assess how PV30 and IV30 perform in a simulation of herds with different reproductive management and physiology and to compare them to indicators of reproductive performance that do not consider the herd voluntary waiting period.
Methods
To evaluate the reproductive indicators we used the SimHerd-program, a stochastic simulation model, and 18 scenarios were simulated. The scenarios were designed by altering the reproductive management efficiency and the status of reproductive physiology of the herd. Logistic regression models, together with receiver operating characteristics (ROC), were used to examine how well the reproductive performance indicators could discriminate between herds of different levels of reproductive management efficiency or reproductive physiology.
Results
The logistic regression models with the ROC analysis showed that IV30 was the indicator that best discriminated between different levels of management efficiency followed by PV30, calving interval, 200-days not-in calf-rate (NotIC200), in calf rate at100-days (IC100) and a fertility index. For reproductive physiology the ROC analysis showed that the fertility index was the indicator that best discriminated between different levels, followed by PV30, NotIC200, IC100 and the calving interval. IV30 could not discriminate between the two levels.
Conclusion
PV30 is the single best performance indicator for estimating the level of both herd management efficiency and reproductive physiology followed by NotIC200 and IC100. This indicates that PV30 could be a potential candidate for inclusion in dairy herd improvement schemes.
Keywords: Cattle, dairy, reproductive performance, voluntary waiting period
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