Evaluation of two dairy herd reproductive performance indicators that are adjusted for voluntary waiting period

Abstract

BackgroundOverall 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.MethodsTo 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.ResultsThe 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.ConclusionPV30 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.

Estrus traits derived from activity measurements are heritable and closely related to the time from calving to first insemination

“…Early onset of estrus cyclicity with clear estrus behavior increases the chance of a successful insemination after calving, both because it shortens the time from calving to estrus and also because it increases the conception rate at estrus, and thereby reduces the number of services per conception (Darwash et al, 1997a). However, CFI is influenced by management strategies; for example, by imposing a voluntary waiting period (Löf et al, 2012) or inseminating high-yielding cows later than low-yielding cows (Andersen-Ranberg et al, 2005). Consequently, 3471 estimated CFI heritability is usually low, ranging from 0.03 to 0.13 (Roxström et al, 2001a;Andersen-Ranberg et al, 2005;Sun et al, 2009).…”

Factors influencing the chance of cows being pregnant 30 days after the herd voluntary waiting period

“…One way to control for different herd reproductive management strategies and to better reflect the biological reproductive performance of the cow is to use an indicator that controls for reproductive strategy Factors influencing the chance of cows being pregnant 30 days after the herd voluntary waiting period E. Löf ,* † 1 H. Gustafsson , † ‡ and U. Emanuelson * decisions at the herd level. We previously investigated a herd reproductive performance indicator that was adjusted for herd VWP: proportion pregnant after the herd VWP plus 30 d (PV30) and found that it outperformed many other indicators (Löf et al, 2012). Such an indicator can also facilitate benchmarking between herds with different length of VWP.…”

Modelling impacts of performance on the probability of reproducing, and thereby on productive lifespan, allow prediction of lifetime efficiency in dairy cows

“…Thereafter the cow is assumed to have an oestrus of 3 days, which takes place 21.8 ± 3 days after the previous oestrus period. The breeding period commences after a voluntary waiting period, set to 50 days (Löf et al, 2012). Before the end of the voluntary waiting period and outwith the 3-day oestrus window, LCONC is assumed to be zero.…”