Assessment of different methods to estimate bovine colostrum quality on farm.

AIMS: To evaluate two different hydrometers and an optical and a digital Brix refractometer for the assessment of bovine colostrum quality, in terms of accuracy and precision compared with the measurement of IgG concentrations using radial immunodiffusion (RID), and to evaluate the reliability and repeatability of the Brix refractometers. METHODS: To determine reliability and repeatability, 145 colostrum samples were tested by two independent observers twice, using the optical and digital Brix refractometers. A further 193 colostrum samples from Holstein cows were collected on one commercial dairy farm at first milking and tested with two hydrometers and an optical and digital Brix refractometer. An aliquot of each sample was frozen for RID measurement of IgG concentrations and samples were classified as poor (≤50 g IgG/L) or good (>50 g IgG/L) quality colostrum. Intraclass correlation coefficients (ICC) were used to determine inter- and intra-observer reliability and repeatability. Optimised cut-off values for the four devices were determined using receiver operating characteristics (ROC) analysis with the RID results as the reference. Using these cut-offs, sensitivities and specificities for determining good quality colostrum were calculated. RESULTS: The ICC for inter-observer reliability was 0.98 for the optical Brix refractometer, and for intra-observer repeatability was 0.97 and 0.98 for the optical and the digital Brix refractometers, respectively. For the 193 colostrum samples, 67 (34.7%) had concentrations of IgG ≤50 g/L determined by RID. Optimised cut-off values evaluated by ROC analysis were higher for all devices compared with manufacturer reference or previously published values. Using these values, the sensitivities for the two hydrometers, and the optical and the digital Brix refractometers were 0.73, 0.71, 0.56 and 0.79, respectively; specificities were 0.72, 0.61, 0.90 and 0.69, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The Brix refractometers provided the most accurate assessment of colostrum quality of the devices evaluated, and demonstrated excellent precision in terms of repeatability. To provide optimal health for newborn calves, a sufficient intake of good quality colostrum is essential. The Brix refractometers provide rapid, convenient tools for classification of colostrum quality.

Evaluation of 2 electronic handheld devices for diagnosis of ketonemia and glycemia in dairy goats.

The objective of this study was to evaluate the suitability of the electronic handheld devices FreeStyle Precision (FSP; Abbott Germany, Wiesbaden, Germany) and GlucoMen LX Plus (GML; A. Menarini GmbH, Vienna, Austria) for the measurement of ß-hydroxybutyrate (BHBA) in whole blood in dairy goats. Additionally, glucose concentration was analyzed with the FSP device. For method comparison, the samples were also analyzed in the laboratory by standard methods, which served as the gold standard in our study. A further objective was to evaluate the agreement between samples obtained by minimal invasive venipuncture of an ear vein and measurements of whole blood samples from the jugular vein (vena jugularis). In total, 173 blood sample pairs collected from 28 goats were obtained from an ear vein and from the jugular vein. The Spearman correlation coefficients (rsp) for BHBA concentrations determined with the FSP or GML and the gold standard were 0.95 and 0.85 for the ear vein and 0.98 and 0.88 for the jugular vein, respectively. Bland-Altman plots of differences showed a positive bias of 0.12 (ear vein) and 0.21 (jugular vein) when determination was performed with the FSP and a negative bias of 0.21 (ear vein) and 0.24 (jugular vein) when using the GML. For the FSP, applying the adjusted thresholds determined by ROC analysis of 0.9 (ear vein) and 1.0 mmol/L (jugular vein) allowed to distinguish between healthy goats and animals with hyperketonemia with sensitivities (Se) and specificities (Sp) for samples from the ear vein of 0.98 and 0.85, and from the jugular vein of 0.99 and 0.94, respectively. For the GML, adjusted thresholds were 0.5 mmol/L for the ear vein (Se=0.94, Sp=0.75) and 0.6 mmol/L for the jugular vein (Se=0.88, Sp=0.91). Repeated analyses of defined whole blood samples showed average inter- and intraassay coefficients of variation of 6.6 and 7.3% for FSP, and of 35.6 and 35.4% for GML, respectively. Test characteristics for determining glucose concentration with the FSP compared with the gold standard were poor (ear vein: rsp=0.41; jugular vein: rsp=0.51), with low validity to distinguish between hypo- and normoglycemia (Se=0.71, Sp=0.66). The present study showed good test characteristics for the FSP and moderate for the GML device for determining BHBA concentrations in whole blood. Additionally the results demonstrate the suitability of testing BHBA concentration in a blood drop obtained from an ear vein. Based on the results of this study, the FSP device is not suitable to differentiate normo- from hypoglycemia in goats.

Pain management with flunixin meglumine at dehorning of calves.

Dehorning (DH) of calves is a common procedure on commercial dairy farms. Pain management of calves has been investigated in several studies. It is generally accepted that the use of local anesthesia before DH is essential for pain management. Postoperative inflammatory pain should be treated by using a nonsteroidal antiinflammatory drug. The objective of this controlled, randomized, and blinded clinical trial was to determine the effects of the nonsteroidal antiinflammatory drug flunixin meglumine before DH on cortisol concentrations in sera of 5- to 9-wk old calves. Furthermore, selected behavioral characteristics and heart and respiratory rate were examined to assess pain in the hours after dehorning. A total of 80 calves were allocated to 4 groups. In each of 20 replicates, 4 calves were randomly assigned to the following groups: in 3 treatment groups, calves received a local anesthetic (10 mL of procain hydrochloride) and a first treatment (i.v.) with flunixin meglumine or a placebo 20 min before hot-iron dehorning, and a second treatment with flunixin meglumine or a placebo (0.9% saline) 3 h after DH. Calves in the control (CON) group were not dehorned and did not receive any treatment. Groups received 2.2 mg of flunixin meglumine/kg followed by a placebo (FP), 2.2 mg of flunixin meglumine/kg for both treatments (FF), or a placebo for both treatments (PP). Blood samples were collected from all calves, including CON calves, 20 min before restraint in a headlock for DH, 2 min after DH, as well as 30 min and 1, 2, 4, 6, and 8 h after DH. Samples were analyzed for concentration of cortisol by enzyme immunoassay. It was found that concentration of cortisol, calculated as area under the curve, was greater in PP compared with FF and tended to be greater compared with FP. Significant differences between PP and FF were detected at 30 min and 2 h after DH. Throughout the observation period, cortisol concentrations were in both flunixin meglumine-treated groups at a similar level as in the CON group. The heart and respiratory rates showed neither difference between the CON group and the 3 dehorned groups nor between the treatment groups.