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Diagnostic Evaluation of Fat to Protein Ratio in Prolonged Calving to Conception Interval Using Receiver Operating Characteristic Analyses
Author(s) -
Podpečan O,
Mrkun J,
Zrimšek P
Publication year - 2008
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/j.1439-0531.2007.00895.x
Subject(s) - receiver operating characteristic , herd , rank correlation , zoology , ice calving , spearman's rank correlation coefficient , mathematics , statistics , dairy cattle , biology , lactation , pregnancy , genetics
Contents 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.