Hyperketonemia In Dairy Cows Research Articles

Effects of peripartal glucose precursor supplementation on lactation performance and metabolic health of primiparous and multiparous dairy cows.

Hyperketonemia remains a major metabolic issue of serious milk production and a major health concern in early lactation cows. Oral supplementation of glucose precursors (GP) can be used to prevent hyperketonemia in dairy cows. The objective of this study was to compare the beneficial effects of orally supplementing a mixture of GP on metabolic health indicators and milk production status of primiparous (PP) and multiparous (MP) dairy cows. Twenty-eight Holstein cows were blocked by expected date of parturition, previous lactation yield, and parity. The cows were randomly allocated to one of the four treatment groups (n = 7 cows/group) based on their parity and GP supplementation: i) PP cows fed basal diet only (PP-CON), ii) PP cows with oral supplementation of GP (PP-GP), iii) MP cows fed basal diet only (MP-CON), and iv) MP cows with oral supplementation of GP (MP-GP). Glucose precursor (glycoline liquid) was orally drenched (300 mL/d) in GP cows from 7 days prepartum through 7 days postpartum. Other than GP supplementation, all cows were fed similar pre- and postpartum basal diets. In both pre- and postpartum periods, serum glucose concentration was increased, whereas β-hydroxybutyrate and free fatty acids were decreased in GP cows compared with the CON cows. Milk yield and milk components were statistically not different between GP and CON cows over the first 9 week of lactation. The yield of actual milk, energy-corrected milk, 63-days cumulative milk, colostrum yield, and calf birth weight remained higher in MP cows compared with PP cows. Oral drenching of GP around calving can be recommended to successfully improve the metabolic health and reduce the negative effects of hyperketonemia not only in MP but also in PP dairy cows.

A randomized controlled trial to evaluate propylene glycol alone or in combination with dextrose as a treatment for hyperketonemia in dairy cows

Our objective was to investigate the effect of i.v. dextrose as an adjunct therapy to oral propylene glycol on the resolution of hyperketonemia (HYK; blood β-hydroxybutyrate ≥1.2 mmol/L), disease incidence, and early lactation milk yield. Cows (n = 1,249) between 3 and 16 d in milk (DIM) from 4 New York dairy farms were screened once weekly for HYK for 2 wk. Those with HYK and no previous history of retained placenta, metritis, or HYK were randomly assigned to 1 of 3 treatment groups: 300 mL of oral 100% propylene glycol for 3 d (PG3); 300 mL of oral 100% propylene glycol for 3 d plus 500 mL i.v. 50% dextrose on d 1 (PG3D1); or 300 mL of oral 100% propylene glycol for 3 d plus 500 mL i.v. 50% dextrose on all 3 d (PG3D3). Cows with a blood β-hydroxybutyrate <1.2 mmol/L at initial screening were re-screened the following week and randomly assigned to the above treatment groups if blood β-hydroxybutyrate was ≥1.2 mmol/L. Cows were assessed for post-treatment HYK resolution 1 and 2 wk after initial HYK diagnosis. We collected farm-diagnosed occurrence of adverse events (sold, died, metritis, displaced abomasum, or ketosis) during the first 60 DIM and milk yield data from the first 10 wk of lactation from herd management software. We used mixed-effects multivariable Poisson regression models to assess the risk of post-treatment HYK resolution at 1 and 2 wk following initial HYK diagnosis and adverse event occurrence among treated cows. We used repeated-measures ANOVA to assess differences in average daily milk yield between treatments. The overall HYK incidence was 30.1% (n = 373). Sixty-four percent of cows (n = 237) were assigned to a treatment group in the first week (3 to 9 DIM), and 36% (n = 136) assigned the second week (10 to 16 DIM). The incidence of 1 or more adverse events during the first 60 DIM was 9.4% (n = 35). We found no effect of treatment on risk of post-treatment HYK resolution at wk 1 (PG3 56.9%, PG3D1 45.0%, PG3D3 50.0%) or wk 2 (PG3 60.0%, PG3D1 52.1%, PG3D3 59.5%) following initial diagnosis, or for risk of adverse event occurrence (PG3 7.4%, PG3D1 8.0%, PG3D3 12.6%). Average daily milk yield (mean ± SE) was similar between treatment groups (PG3: 42.7 ± 0.6 kg/d, PG3D1: 42.4 ± 0.6 kg/d, PG3D3: 42.6 ± 0.6 kg/d). The addition of dextrose for 1 or 3 d provided no improvement in resolution of ketosis assessed once weekly, reduction in adverse events during the first 60 d of lactation, or a difference in average daily milk yield during the first 10 wk of lactation.

Randomized control trial to evaluate propylene glycol alone or in combination with dextrose as a treatment for hyperketonemia in dairy cows

Postpartum dairy cows undergo a period of energy deficit that can lead to excessive lipolysis and formation of ketone bodies such as β-hydroxybutyrate (BHB). Cows that are hyperketonemic (HYK; blood [BHB] ≥1.2mmol/L) are at greater risk of adverse events during early lactation. Although 300 ml of oral propylene glycol (PG) has been shown to reduce these negative effects, the efficacy of intravenous (IV) dextrose is unclear. Our objective was to investigate the impact of IV dextrose as an adjunct therapy to PG on HYK resolution, disease incidence, and milk yield.

Short communication: Prediction of hyperketonemia in dairy cows in early lactation using on-farm cow data and net energy intake by partial least square discriminant analysis

The objectives of this study were (1) to evaluate if hyperketonemia in dairy cows (defined as plasma β-hydroxybutyrate ≥1.0 mmol/L) can be predicted using on-farm cow data either in current or previous lactation week, and (2) to study if adding individual net energy intake (NEI) can improve the predictive ability of the model. Plasma β-hydroxybutyrate concentration, on-farm cow data (milk yield, percentage of fat, protein and lactose, fat- and protein-corrected milk yield, body weight, body weight change, dry period length, parity, and somatic cell count), and NEI of 424 individual cows were available weekly through lactation wk 1 to 5 postpartum. To predict hyperketonemia in dairy cows, models were first trained by partial least square discriminant analysis, using on-farm cow data in the same or previous lactation week. Second, NEI was included in models to evaluate the improvement of the predictability of the models. Through leave-one trial-out cross-validation, models were evaluated by accuracy (the ratio of the sum of true positive and true negative), sensitivity (68.2% to 84.9%), specificity (61.5% to 98.7%), positive predictive value (57.7% to 98.7%), and negative predictive value (66.2% to 86.1%) to predict hyperketonemia of dairy cows. Through lactation wk 1 to 5, the accuracy to predict hyperketonemia using data in the same week was 64.4% to 85.5% (on-farm cow data only), 66.1% to 87.0% (model including NEI), and using data in the previous week was 58.5% to 82.0% (on-farm cow data only), 59.7% to 85.1% (model including NEI). An improvement of the accuracy of the model due to including NEI ranged among lactation weeks from 1.0% to 4.4% when using data in the same lactation week and 0.2% to 6.6% when using data in the previous lactation week. In conclusion, trained models via partial least square discriminant analysis have potential to predict hyperketonemia in dairy cows not only using data in the current lactation week, but also using data in the previous lactation week. Net energy intake can improve the accuracy of the model, but only to a limited extent. Besides NEI, body weight, body weight change, milk fat, and protein content were important variables to predict hyperketonemia, but their rank of importance differed across lactation weeks.

Short communication: Assessing the accuracy of inline milk fat-to-protein ratio data as an indicator of hyperketonemia in dairy cows in herds with automated milking systems

The objective of this study was to evaluate the accuracy of inline milk fat-to-protein (F:P) data to detect hyperketonemia (HYK) in herds with automated milking systems (AMS). The F:P ratio has been investigated as a tool for detecting HYK with moderate accuracy in past studies, but inline F:P data in AMS may also be useful for HYK screening. To assess the accuracy of these data in commercial settings, we monitored 484 cows from 9 AMS herds for their first 3 wk of lactation, taking blood samples once per week (n = 1,427). Positive cases of HYK were defined by whole-blood β-hydroxybutyrate (BHB) concentrations ≥1.2 or ≥1.4 mmol/L. Milk data were collected from the AMS software on each farm for each cow and converted into 4 different F:P values: (1) value from the same day as the BHB test; (2) 5-d centered-moving average (CMA); (3) 5-d backward-moving average (BMA); (4) 5-d forward-moving average (FMA). In linear regression models, all 4 values were associated with BHB, but slope estimates varied and R2 were low: same day (slope = 0.95, R2 = 0.07), CMA (slope = 1.05, R2 = 0.07), BMA (slope = 0.65, R2 = 0.04), and FMA (slope = 1.23, R2 = 0.09). In logistic regression models, the odds of having HYK (BHB ≥1.2 mmol/L) increased with every 0.1-unit increase from the mean F:P ratio (1.16) using same-day values (odds ratio = 1.35, 95% confidence interval = 1.25-1.47) and CMA (odds ratio = 1.39, 95% confidence interval = 1.27-1.51). The same increase in F:P from mean BMA (1.14) and FMA (1.17) was associated with 1.22 and 1.49 times the odds of HYK, respectively. For all 4 F:P variations, we evaluated the sensitivity, specificity, positive predictive value, and negative predictive value of different F:P thresholds with HYK status. As the F:P threshold increased from 1.17 to 1.50, sensitivity decreased (range: 77 to 9%) but specificity increased (range: 58 to 96%). Same-day and CMA F:P cutoffs at which a balance was reached between sensitivity and specificity ranged from 1.18 to 1.22; however, even at these values we found high rates of false positives and negatives (range: 31-39%). These results suggest that inline milk F:P data from inconsistently calibrated sensors should not be used alone to detect HYK in AMS herds.

Prepartum supplementation of conjugated linoleic acids (CLA) increased milk energy output and decreased serum fatty acids and β-hydroxybutyrate in early lactation dairy cows.

Prepartum supplementation with conjugated linoleic acid (CLA) may influence lipolysis and hyperketonemia in dairy cows. The objective of this study was to examine the effect of prepartum CLA supplementation on lactation performance and serum fatty acids (FA) and β-hydroxybutyrate (BHB) in early lactation dairy cows, and secondarily on reproductive performance. Multiparous cows were enrolled in the study at 18 days prior to expected calving date, and randomly assigned 100 g/day of Lutrell Pure (BASF, Ludwigshafen, Germany; 75% FA), providing 10 g/day of each CLA isomer (trans-10 cis-12 and cis-9 trans-11 CLA) or equivalent amount of rumen inert fatty acids as control (78 g/day of Energy Booster 100; Milk Specialties Global, Eden Prairie, MN). Treatments were top dressed daily to individual cows from enrollment to calving and all cows were offered the same ration. Blood samples were collected on the first day of supplementation, 10 days prepartum, and 1, 7, 14, and 30 days postpartum. Hyperketonemia was defined as serum BHB ≥ 1.2 mM. Milk yield was recorded daily until 60 days postpartum and averaged weekly. Milk samples were obtained weekly for component analysis. Prepartum CLA supplementation tended to increase serum concentration of cis-9, trans-11 CLA and increased trans-10, cis-12 CLA prepartum. Cows supplemented with CLA had increased milk protein yield and tended to have increased milk fat yield and milk yield, which together resulted in greater energy content of milk. Cows supplemented with CLA had lower serum FA on day 1 and 7 postpartum and overall lower serum BHB postpartum, which resulted in decreased prevalence of hyperketonemia on day 14 postpartum. There were no differences in body condition score change, other health disorders, or reproductive outcomes by treatment. Together, these findings indicate that prepartum CLA supplementation may be a plausible strategy to positively influence postpartum performance.

Technical note: Validation of the BHBCheck blood β-hydroxybutyrate meter as a diagnostic tool for hyperketonemia in dairy cows

Accurate cow-side blood β-hydroxybutyrate (BHB) detection meters are valuable tools for rapid diagnosis of hyperketonemia. The main objective of this study was to compare the blood BHB measured in whole blood by the BHBCheck meter (PortaCheck, Moorestown, NJ) to a previously validated meter, Precision Xtra meter (Abbott Laboratories, Abbott Park, IL) and a colorimetric laboratory assay. Samples (n = 426) were collected from postpartum primiparous and multiparous Holstein cows (n = 79 cows) enrolled in 1 of 2 experiments (Exp) with different sampling schedules (Exp 1: n = 39 cows, 58 samples; Exp 2: n = 40 cows, 368 samples). In both Exp, whole-blood samples were collected from the coccygeal vessels after morning milking, before morning feeding. Blood samples were used immediately for BHB quantification via the BHBCheck meter and the Precision Xtra meter. Blood was also collected into evacuated tubes containing no additive (Exp 1) or potassium oxalate/sodium fluoride (Exp 2), which were centrifuged for serum or plasma separation and stored at -20°C for subsequent analysis. Laboratory quantification of BHB concentration was done by the BHB LiquiColor Assay (EKF Diagnostics-Stanbio, Boerne, TX; certified for serum and plasma). Data were analyzed by UNIVARIATE, CORR, FREQ, REG, and LOGISTIC procedures of SAS 9.4 (SAS Institute Inc., Cary, NC). Within this sample set, average parity was 3.3 lactations and DIM was 14 d. The proportion of samples classified as hyperketonemia (BHB ≥1.2 mmol/L) was 25, 28, and 31% as determined by the colorimetric assay, BHBCheck meter, and Precision Xtra meter, respectively. The correlation for BHBCheck meter BHB concentration compared with the colorimetric assay concentrations was r = 0.96, with a sensitivity of 91% and specificity of 93%. Correlation, sensitivity, and specificity of the Precision Xtra meter concentrations were 0.97, 98%, and 92%, respectively. Bland-Altman plots demonstrated minimal bias for both meters. Area under the receiver operator characteristic curve suggests adequate diagnostic accuracy of both meters. Overall, accuracy, sensitivity, and specificity of the BHBCheck meter was similar to the Precision Xtra meter and laboratory assay, indicating the BHBCheck meter is appropriate for use as a cow-side diagnostic test for hyperketonemia in dairy cows.

The effect of different treatments for early-lactation hyperketonemia on liver triglycerides, glycogen, and expression of key metabolic enzymes in dairy cattle

Despite the widespread use of treatments for postpartum hyperketonemia in dairy cows, there is currently a lack of evidence comparing their effects on both the resolution of hyperketonemia and the potential effects on the liver of affected animals. The objective of our work was to investigate the effect of commonly used hyperketonemia treatments on hepatic triglyceride and glycogen content as well as on the mRNA and protein abundance of key enzymes involved in gluconeogenesis, ketogenesis, and lipid metabolism. Multiparous Holstein cows between 3 and 9 d in milk were screened 3 times per week and enrolled in the study when whole-blood β-hydroxybutyrate concentrations measured ≥1.2 mmol/L. Cows were randomly allocated to 1 of 4 groups: (1) 500 mL of a 50% d-glucose solution intravenously once a day for 3 d (n = 8), (2) 300 mL of propylene glycol orally once a day for 3 d (n = 8), (3) 500 mL of a 50% d-glucose solution intravenously and 300 mL of propylene glycol orally once a day for 3 d (n = 8), or (4) an untreated control group (n = 8). Liver biopsies were taken on the day of enrollment as well as on the day following completion of treatments. Liver triglyceride and glycogen content were determined by colorimetric and fluorometric methods, respectively. Gene and protein expression of pyruvate carboxylase, phosphoenolpyruvate carboxykinase 1, glucose-6-phosphatase, 3-hydroxy-3-methylglutaryl-CoA synthase 2, acetyl-CoA carboxylase, and carnitine palmitoyltransferase 1A were compared between groups and time points using quantitative reverse transcriptase PCR and Western blotting techniques, respectively. In addition, the ratio of light chain 3B II:I was determined by Western blotting. Plasma samples from both time points for each enrolled cow were submitted for chemistry analysis. Data were analyzed using a repeated-measures ANOVA taking into account the paired nature of the data, and differences between all groups and time points were controlled for multiple comparisons using the Tukey procedure. No difference was found in triglyceride or glycogen concentration between treatment groups. The gene expression of pyruvate carboxylase decreased in the group receiving both treatments, whereas protein expression of this enzyme increased in all groups over time. The autophagy marker light chain 3B II:I decreased in the group receiving both glucose and propylene glycol. No other changes in gene or protein expression of key hepatic enzymes were associated with treatments. We conclude that intravenous glucose and oral propylene glycol, commonly used treatments for ketosis in postpartum dairy cows, administered alone or in combination for a duration of 3 d did not have important beneficial or detrimental effects on selected indicators of liver composition and function in cows with hyperketonemia.

Comparison of four electronic cowside tests for diagnosing hyperketonemia in dairy cows

The objective of this study was to evaluate 4 cowside ketone meters for use in on-farm β-hydroxybutyrate (BHB) monitoring of hyperketonemia (HYK) in transition dairy cows.

Technical note: Comparison of 4 electronic handheld meters for diagnosing hyperketonemia in dairy cows

The objective of this study was to evaluate 4 handheld ketone meters for use in on-farm β-hydroxybutyrate (BHB) monitoring of hyperketonemia in transition dairy cows. Blood samples taken from 250 Holstein cows between 262d pregnant and 15d in milk were evaluated on 4 different handheld ketone meters: Precision Xtra (Abbott Laboratories, Abbott Park, IL), TaiDoc (Pharmadoc, Lüdersdorf, Germany), Nova Max (Nova Biomedical, Billerica, MA), and Nova Vet (Nova Biomedical). Samples were screened using the Precision Xtra and tested on the remaining 3 m if the sample BHB concentration fell into predetermined ranges. A total of 89 samples were used for analysis. Performance of each meter was compared with the average of 2 plasma BHB concentrations both determined by a gold standard spectrophotometric Randox assay performed at 2 independent laboratories. Agreement between the 2 laboratories was very strong (Pearson correlation=0.998). All meters had Pearson correlation coefficients greater than 0.95. The Precision Xtra and TaiDoc meters were 100.0% sensitive and 73.5% specific at a BHB concentration cut point of 1.2mmol/L. The Nova Vet and Nova Max meters had sensitivities of 94.9 and 74.4% and specificities of 91.8 and 100.0%, respectively, at the same cut point. Agreement between the gold standard and the handheld meter was the best for the Nova Vet meter when evaluated using a Bland Altman graph with a mean BHB difference of 0.08mmol/L. Trends in bias were noted with the Precision Xtra and Nova Max meters resulting in increasing average discrepancy between the gold standard and the meter for both at higher plasma BHB concentrations and mean BHB differences of -0.34 and 0.26mmol/L, respectively. The coefficient of variation was <10% for the Precision Xtra, TaiDoc, and Nova Vet meters, and <15% for the Nova Max meter. We conclude that the TaiDoc and Nova Vet meters, similar to the already validated Precision Xtra meter, are acceptable for use in on-farm testing for monitoring and treatment of hyperketonemia.

Measurement of β-hydroxybutyrate in capillary blood obtained from an ear to detect hyperketonemia in dairy cows by using an electronic handheld device

The primary objective of the present study was to test whether capillary blood obtained by puncturing the skin of an ear with a minimal invasive lancet technique is able to detect hyperketonemia (HYK) in dairy cows. Furthermore, test characteristics of a new available handheld device, the FreeStyle Precision Neo (FSP-Neo, Abbott GmbH & Co. KG, Wiesbaden, Germany) for determination of β-hydroxybutyrate (BHB) concentrations in bovine blood were evaluated by comparing the measurements with a laboratory reference. The BHB concentration was determined with the FSP-Neo device in 720 capillary blood samples from 3 different sampling sites (left, right ear, and repeated measurement) and in 240 samples from a coccygeal vessel. The concentration of BHB in serum harvested from the coccygeal blood samples was analyzed at the laboratory and was used as reference. The Spearman correlation coefficient (ρs) between the BHB concentrations in capillary blood measured with the handheld device and the reference test was between 0.76 and 0.81. Using capillary blood, the mean ± standard deviation BHB difference compared with the reference test was 0.20±0.47 mmol/L for all 3 sampling locations at the ears. The receiver operating characteristic analyses for the FSP-Neo device resulted in an optimized threshold for the detection of subclinical ketosis (SCK) in capillary blood of 1.3 mmol/L (left and right ear) and 1.2 mmol/L (repeated measurements). Applying these adjusted threshold sensitivities (Se) for all 3 capillary sampling sites at the ear were 100%, and specificities (Sp) ranged between 93 and 94%. Hence, we conclude that all sampling locations were suitable to identify cows suffering from SCK. The reference test compared with BHB measurements in coccygeal blood resulted in a ρs of 0.92 with a mean ± standard deviation of 0.02±0.21 mmol/L. The receiver operating characteristic analyses for the FSP-Neo device resulted in an optimized threshold for the detection of SCK in coccygeal blood of 1.1 mmol/L, with a corresponding Se and Sp of 100 and 95%, respectively. Because capillary blood is easily achievable from an ear, particularly if animals are fixed in headlocks for routine checkups, this technique is considered as an additional minimally invasive method for the identification of dairy cows suffering from HYK.

Accuracy of milk ketone bodies from flow-injection analysis for the diagnosis of hyperketonemia in dairy cows

The objectives of this study were (1) to determine the correlations between blood β-hydroxybutyrate (BHBA) and milk components [BHBA, acetone, fat, protein, and fat:protein (F:P) ratio], and (2) to establish optimal thresholds for milk components to predict hyperketonemia in dairy cows. Data on 163 cows from 37 herds were used in this cross-sectional study. Herds were visited once during the study period, and cows between 2 and 90 d in milk were blood sampled within 4h of milk sampling for the Dairy Herd Improvement test. Blood BHBA concentrations were measured using a cow-side electronic meter, Precision Xtra, which was considered the gold standard test in this study. Milk BHBA and acetone concentrations were measured in Dairy Herd Improvement milk samples by flow-injection analysis; whereas, milk fat and protein were tested using Fourier transform infrared spectroscopy. Hyperketonemia was defined by a blood BHBA concentration ≥1.4mmol/L. The prevalence of hyperketonemia (based on blood BHBA values) in this study population was 21.0%. Pearson correlation coefficients between blood BHBA and milk BHBA, acetone, fat, protein, and F:P ratio were 0.89, 0.73, 0.21, 0.04, and 0.17, respectively. Receiver operating characteristic curves were generated and thresholds for each individual milk component were determined based on the maximal sum of sensitivity and specificity. Optimal threshold values for hyperketonemia were milk BHBA ≥0.20mmol/L, acetone ≥0.08mmol/L, fat ≥4.2%, and F:P ratio ≥1.3. Based on these thresholds, milk BHBA and acetone had greater sensitivity (84 and 87%, respectively) and greater specificity (96 and 95%, respectively) than the other milk components (fat, protein, and F:P). Series and parallel testing slightly improved the accuracy of milk BHBA and acetone values to predict hyperketonemia. A multivariable model that accounted for milk BHBA and milk acetone values simultaneously had the highest accuracy of all tested models for predicting hyperketonemia. These results support that milk BHBA and milk acetone values from flow-injection analysis are accurate diagnostic tools for hyperketonemia in dairy cows and could potentially be used for herd-level hyperketonemia surveillance programs.

Detection of hyperketonemia in dairy cows

Over the past years, hyperketonemia has been shown to be associated with health and production of postpartum dairy cows. Many tests are available to detect hyperketonemia in blood, urine, and milk. A procedure that quantifies ketone bodies in milk is now available through the dairy herd improvement association (DHIA) sampling process; however, conflicting data are reported on the accuracy of this procedure. The main objective of this study was to validate the relationship between blood β-hydroxybutyrate acid (BHBA) concentration and the concentrations of various milk components such as ketone bodies (BHBA and acetone), fat, protein, lactose, urea, and somatic cell count (SCC). A second objective was to identify thresholds for these indicators to diagnose hyperketonemia in dairy cows for surveillance purposes.

Routine detection of hyperketonemia in dairy cows using Fourier transform infrared spectroscopy analysis of β-hydroxybutyrate and acetone in milk in combination with test-day information

The objective of this study was to assess the quality of a diagnostic model for the detection of hyperketonemia in early lactation dairy cows at test days. This diagnostic model comprised acetone and β-hydroxybutyrate (BHBA) concentrations in milk, as determined by Fourier transform infrared (FTIR) spectroscopy, in addition to other available test-day information. Plasma BHBA concentration was determined at a regular test day in 1,678 cows between 5 and 60 d in milk, originating from 118 randomly selected farms in the Netherlands. The observed prevalence of hyperketonemia (defined as plasma BHBA ≥1,200µmol/L) was 11.2%. The value of FTIR predictions of milk acetone and milk BHBA concentrations as single tests for hyperketonemia were found limited, given the relatively large number of false positive test-day results. Therefore, a multivariate logistic regression model with a random herd effect was constructed, using parity, season, milk fat-to-protein ratio, and FTIR predictions of milk acetone and milk BHBA as predictive variables. This diagnostic model had 82.4% sensitivity and 83.8% specificity at the optimal cutoff value (defined as maximum sum of sensitivity and specificity) for the detection of hyperketonemia at test days. Increasing the cutoff value of the model to obtain a specificity of 95% increased the predicted value of a positive test result to 56.5%. Confirmation of test-positive samples with wet chemistry analysis of milk acetone or milk BHBA concentrations (serial testing) improved the diagnostic performance of the test procedure. The presented model was considered not suitable for individual detection of cows with ketosis due to the length of the test-day interval and the low positive predictive values of the investigated test procedures. The diagnostic model is, in our opinion, valuable for herd-level monitoring of hyperketonemia, especially when the model is combined with wet chemistry analysis of milk acetone or milk BHBA concentrations. By using the diagnostic model in combination with wet chemistry milk BHBA analysis, 84% of herds were correctly classified at a 10% alarm-level prevalence. As misclassification of herds may particularly occur when only a limited number of fresh cows are sampled, we suggest using prevalence estimates over several consecutive test days to evaluate feeding and management practices in smaller dairy farms.

Protein and fat mobilization and associations with serum β-hydroxybutyrate concentrations in dairy cows

The objective of this study was to obtain information on variation between dairy cows in muscle and fat tissue mobilization around parturition and to study the association between protein and fat mobilization and serum β-hydroxybutyrate (BHBA) concentrations (hyperketonemia) in this period. Thirty-four cows kept under similar conditions at a university dairy farm (no experimental treatments) were monitored from 4 wk before until 8 wk after calving. Mobilization of muscle protein was investigated by analysis of plasma 3-methylhistidine concentrations (3-MH, analyzed by a recently developed HPLC tandem mass spectrometry method) and ultrasound measurements of longissimus muscle thickness. Mobilization of fat tissue was monitored by serum nonesterified fatty acid (NEFA) concentrations and ultrasound measurements of backfat thickness. Large variation was observed between cows in onset and duration of periparturient protein and fat mobilization. Plasma 3-MH concentrations and muscle thickness profiles indicated that protein mobilization started, on average, before parturition and continued until approximately wk 4 of lactation. Serum NEFA concentrations and backfat thickness profiles showed that fat mobilization occurred from parturition until the end of the study. Thus, muscle protein mobilization occurred in advance of fat mobilization in most cows from this study. We hypothesized that this might be due to a prepartum amino acid deficiency in the absence of negative energy balance. The incidence of hyperketonemia in this study was 16/34 = 47%. With the exception of 3 cows defined as having severe hyperketonemia, cows with lower 3-MH concentrations had higher serum BHBA concentrations. A possible explanation for this observation might be that higher mobilization of protein around calving might restrict ketone body production due to the higher availability of glucogenic precursors in the period of most severe negative energy balance and highest fat mobilization. The validity of this hypothesis needs to be confirmed, but data from this study indicate that further research on the role of protein mobilization in the etiology of hyperketonemia in dairy cows is needed.

Short communication: Ketone body concentration in milk determined by Fourier transform infrared spectroscopy: Value for the detection of hyperketonemia in dairy cows

The objective of this study was to evaluate Fourier transform infrared (FTIR) spectrometry to measure milk ketone bodies to detect hyperketonemic cows and compare this method with milk fat to protein ratio to detect hyperketonemia. Plasma and milk samples were obtained weekly from calving to wk 9 postpartum from 69 high-producing dairy cows. The reference test for hyperketonemia was defined as plasma concentration of β-hydroxybutyrate (BHBA) ≥1,200μmol/L. The weekly prevalence of hyperketonemia during the first 9 wk of lactation was, on average, 7.1%. Both BHBA and acetone in milk, determined by FTIR, had a higher sensitivity (80%) to detect hyperketonemia compared with milk fat to protein ratio (66%). Specificity was similar for the 3 diagnostic tests (71, 70, and 71%). In conclusion, FTIR predictions of BHBA or acetone in milk can detect cows with hyperketonemia in early lactation with a higher accuracy compared with the use of milk fat to protein ratio. Because of the high proportion of false-positive tests, there are concerns about the practical applicability of FTIR predictions of acetone, BHBA, and fat to protein ratio in milk to detect hyperketonemic cows.