Improved Detection of Reproductive Status in Dairy Cows Using Milk Progesterone Measurements

Abstract

This study tested a model for predicting reproductive status from in-line milk progesterone ;measurements. The model is that of Friggens and Chagunda [Theriogenology 64 (2005) 155]. Milk progesterone measurements (n = 55 036) representing 578 lactations from 380 cows were used to test the model. Two types of known oestrus were identified: (1) confirmed oestrus (at which insemination resulted in a confirmed pregnancy, n = 121) and (2) ratified oestrus (where the shape of the progesterone profile matched that of the average progesterone profile of a confirmed oestrus, n = 679). The model detected 99.2% of the confirmed oestruses. This included a number of cases (n = 16) where the smoothed progesterone did not decrease below 4 ng/ml. These cows had significantly greater concentrations of progesterone, both minimum and average, suggesting that between cow variation exists in the absolute level of the progesterone profile. Using ratified oestruses, model sensitivity was 93.3% and specificity was 93.7% for detection of oestrus. Examination of false positives showed that they were largely associated with low concentrations of progesterone, fluctuating around the 4 ng/ml threshold. The distribution of time from insemination until the model detected pregnancy failure had a median of 22 days post-insemination. In this test, the model was run using limited inputs, the potential benefits of including additional non-progesterone information were not evaluated. Despite this, the model performed at least as well as other oestrus detection systems.

Mathematical approaches to detect low concentrations in progesterone profiles

“…The second intention of the EWMA CC was to establish a universal threshold for the detection of low progesterone measures during the estrus events. Thus, the LCL in the EWMA CC could be a solution to the concern reported by Friggens et al (2008) who described cow-specific differences in the progesterone levels. Thus, simple threshold method might not be the optimal way to detect the estrus events in the progesterone time series.…”

“…The results are comparable to and sometimes superior to other studies. For example, the method developed by Friggens et al (2008) reached 99.2% of the confirmed estruses and 93.3% of the ratified estruses using progesterone measurements. Firk et al (2003) used activity data and the information about the period since the last estrus event and achieved a sensitivity of 87.9% with an error rate of 12.5%.…”

“…Smoothed progesterone measurements have an important advantage to raw data because of the robustness against outliers. Friggens et al (2008) also discussed the error rate within the ratified estrus cases with progesterone concentrations that fluctuated around their threshold value. They claim that this is the 'main drawback of a simple threshold-based rule, which cannot be overcome by a simple smoothing of the progesterone profiles'.…”

“…For this reason, lower sensitivities of the extended threshold model were not just attributed by the threshold level. Different lactation numbers can also be the reason for differences in error rates between the first and second data set, as Friggens et al (2008) reported on individual progesterone levels between cows, and it cannot be ruled out that the individual progesterone levels become more important between primiparous and multiparous dairy cows. von Leesen, Tetens, Junge and Thaller Simple threshold method This method detected low progesterone concentrations during the estrus event, if one value was below the level of 1.2 ng progesterone/ml skimmed milk and the preceding and following values were above the threshold.…”

“…Indeed, there is only one model that predicted the ovarian activity on the basis of time series of milk progesterone measures (Friggens and Chagunda, 2005). This model estimates the length of postpartum anoestrus, the status of the estrus cycling (follicle phase with low progesterone concentrations, and luteal phases with high progesterone concentrations) and a potential pregnancy status, and was subsequently tested and validated by Friggens et al (2008). The authors obtained a high sensitivity (99.2% for confirmed and 93.3% for simulated estrus events).…”