Predicting hyperketonemia by logistic and linear regression using test-day milk and performance variables in early-lactation Holstein and Jersey cows

Abstract

Although cowside testing strategies for diagnosing hyperketonemia (HYK) are available, many are labor intensive and costly, and some lack sufficient accuracy. Predicting milk ketone bodies by Fourier transform infrared spectrometry during routine milk sampling may offer a more practical monitoring strategy. The objectives of this study were to (1) develop linear and logistic regression models using all available test-day milk and performance variables for predicting HYK and (2) compare prediction methods (Fourier transform infrared milk ketone bodies, linear regression models, and logistic regression models) to determine which is the most predictive of HYK. Given the data available, a secondary objective was to evaluate differences in test-day milk and performance variables (continuous measurements) between Holsteins and Jerseys and between cows with or without HYK within breed. Blood samples were collected on the same day as milk sampling from 658 Holstein and 468 Jersey cows between 5 and 20 d in milk (DIM). Diagnosis of HYK was at a serum β-hydroxybutyrate (BHB) concentration ≥1.2 mmol/L. Concentrations of milk BHB and acetone were predicted by Fourier transform infrared spectrometry (Foss Analytical, Hillerød, Denmark). Thresholds of milk BHB and acetone were tested for diagnostic accuracy, and logistic models were built from continuous variables to predict HYK in primiparous and multiparous cows within breed. Linear models were constructed from continuous variables for primiparous and multiparous cows within breed that were 5 to 11 DIM or 12 to 20 DIM. Milk ketone body thresholds diagnosed HYK with 64.0 to 92.9% accuracy in Holsteins and 59.1 to 86.6% accuracy in Jerseys. Logistic models predicted HYK with 82.6 to 97.3% accuracy. Internally cross-validated multiple linear regression models diagnosed HYK of Holstein cows with 97.8% accuracy for primiparous and 83.3% accuracy for multiparous cows. Accuracy of Jersey models was 81.3% in primiparous and 83.4% in multiparous cows. These results suggest that predicting serum BHB from continuous test-day milk and performance variables could serve as a valuable diagnostic tool for monitoring HYK in Holstein and Jersey herds.

Invited review: β-hydroxybutyrate concentration in blood and milk and its associations with cow performance

“…For this reason, it could be appropriate to record separately HYK risk-estimates for different parity orders and then compute a herd level incidence risk by standardising parityspecific percentages. Conversely, the same pattern has not been observed in Jersey breed, as HYK was more prevalent in primiparous than multiparous cows (Chandler et al, 2018).…”

“…Moreover, it differs from blood measurement of BHB status of the animal as a milk sample represents a period of time. Although laboratory analyses such as photometrical method or enzymatic assays (Chandler et al, 2018) and cowside strip tests (Keto-Test; Berge and Vertenten, 2014) exist in this field, mid-IR spectroscopy (MIRS) is the most promising tool for the determination of milk BHB (Grelet et al, 2016). Indeed, the use of chemical analysis or handheld meter to measure BHB in Figure 2 Author's keywords occurrence map for reviewed studies in dairy cattle.…”

“…Currently, the accuracy of the developed prediction equations for BHB concentration in milk is not high enough to quantify the exact content but it has proved to be useful for screening purposes to detect cows with elevated BHB concentrations in milk (Grelet et al, 2016;Lee et al, 2016;Santschi et al, 2016). Moreover, predicted milk acetone and BHB have been used to develop models for the prediction of blood BHB from test-day milk and performance traits (Chandler et al, 2018), and the use of MIRS milk spectra has been proposed to directly predict blood BHB concentration (Belay et al, 2017a and2017b). Nevertheless, for this approach, we have to consider that usually blood BHB concentration is determined using a single blood sample that represents the status of the animal at the time of blood sampling, whereas a milk sample represents the BHB concentration of a period of time, which could interfere with the accuracy of the developed calibration model.…”

“…Several authors observed a higher frequency of HYK in multiparous than primiparous cows (Santschi et al, 2016;Rathbun et al, 2017;Chandler et al, 2018), and suggested a direct relationship between increasing parity and HYK occurrence. Cumulative incidence from 8.6% to 26.2% (Rathbun et al, 2017) and prevalence from 18.8% to 27.6% (Santschi et al, 2016) have been detected moving from first to third or greater lactation.…”

Predictive ability of host genetics and rumen microbiome for subclinical ketosis

“…Using milk concentrations of ketone bodies will allow a noninvasive method for diagnosis of subclinical ketosis that can be part of routine application. Methods have been developed to predict blood concentrations of ketone bodies using infrared-predicted milk BHB and acetone (e.g., Chandler et al, 2018). If substantial genetic variation is detectable in the milk composition of BHB and acetone, this will open a new avenue for selection against susceptibility to subclinical ketosis, using milk BHB and acetone as indicator traits.…”