Diagnostic Evaluation of Fat to Protein Ratio in Prolonged Calving to Conception Interval Using Receiver Operating Characteristic Analyses

Abstract

Evaluation of fat to protein ratio (FPR) in milk was performed for the prediction of calving to conception interval (CC) in dairy cows. Reproduction parameters of 51 high yielding dairy cows were calculated from farm recording data and milk data record from a regular dairy control. Spearman rank correlation analysis was used to determine the correlation between reproductive parameters of the herd and the milk data record. In the time interval of 75-90 days postpartum the highest correlation was found between FPR and CC (r = 0.414, p < 0.05). Receiver operating characteristics (ROC) analysis was used to evaluate the FPR to distinguish between cows with different CC. The optimal cut-off value at FPR of 1.34 provided the best discrimination power according to CC of 120 days. FPR at 1.44 enabled us 91.7% correct identification of cows with CC above 140 days, where the highest area under the ROC curve of 0.759 and likelihood ratio of 7.2 were observed. FPR </=1.19 was 2.86 times as likely to be found in cows with CC below as in cows with CC above 90 days. The FPR has been shown to be of benefit in the prediction of reproductive efficiency in dairy herds.

Reproductive Performances of Holstein Cows with Different Milk Fat to Protein Ratio during Successive Stages of Lactation

“…In cows with health disorders these authors found differences of 14 (121 vs. 135) days in ketotic and 35 (136 vs. 171) days in cows with reproductive disorders. These authors found the strongest correlation between FPR and reproductive performance of cows during the second month of lactation, as opposed to their previous findings (Podpečan et al, 2008) that this correlation was strongest during the third month of lactation. Results of our study are consistent with the allegations of those authors, and better of them in almost all groups, which is probably caused by used experimental design and limiting the physiological calving to conception interval to 135 days.…”

Clinical Forum: Strategies in metabolic monitoring

“…Heur et al , (1999) found negative effects on fertility in animals with a first test day fat: protein ratio (FPR) >1.5, specifically a reduction in pregnancy rate and calving‐to‐conception interval. Delayed return to cyclicity, reduced pregnancy rates and decreased risk of pregnancy in animals with high FPRs were also findings in several studies, including Gabor et al , (2008) and Podpecan et al , (2008).…”

The relationship between fatty acid profiles in milk identified by Fourier transform infrared spectroscopy and onset of luteal activity in Norwegian dairy cattle

“…A further study found negative effects on fertility in animals with a first-test-day MFPR >1.5 (Heuer et al, 1999). Similarly, MFPR was found to be a useful predictor of whether cows were likely to exceed certain calving-to-conception intervals (Podpecan et al, 2008). Delayed return to cyclicity, reduced pregnancy rates, and decreased risk of pregnancy in animals with high MFPR ratios have also been shown (Loeffler et al, 1999;Gábor et al, 2008;Samarütel et al, 2008).…”