The objective of this study was to evaluate the utility of a digital Brix refractometer for the assessment of success of passive transfer of maternal immunoglobulin compared with the measurement of serum total protein (STP) by refractometry. Blood samples (n = 400) were collected from calves at 3 to 6d of age. Serum IgG concentration was determined by radial immunodiffusion (RID), and STP and percentage Brix (%Brix) were determined using a digital refractometer. The mean IgG concentration was 24.1g/L [standard deviation (SD) ± 10.0] with a range from 2.1 to 59.1g/L. The mean STP concentration was 6.0 g/dL (SD ± 0.8) with a range from 4.4 to 8.8 g/dL. The mean %Brix concentration was 9.2% (SD ± 0.9) with a range of 7.3 to 12.4%. Brix percentage was highly correlated with IgG (r = 0.93). Test characteristics were calculated to assess failure of passive transfer (FPT; serum IgG <10 g/L). The sensitivity and specificity of STP at 5.5 g/dL were 76.3 and 94.4%, respectively. A receiver operating characteristic curve was created to plot the true positive rate against the false positive rate for consecutive %Brix values. The optimal combination of sensitivity (88.9%) and specificity (88.9%) was at 8.4% Brix. Serum total protein was also positively correlated with %Brix (r = 1.00) and IgG (r = 0.93). Dairy producers can successfully monitor their colostrum management and the overall success of passive transfer using a digital Brix refractometer to estimate IgG concentration of colostrum and calf serum.

Recent research suggests that circulating β-hydroxybutyrate (BHB) levels may be a meaningful indicator of grain intake and rumen development in pre-ruminant calves. As such, BHB levels may be a surrogate measure of rumen function to contribute to minimal weaning stress during the transition from liquid to solid feed. The primary objective of this study was to determine the optimal cut-point of circulating BHB levels that would be predictive of sufficient grain intake and rumen development for a successful transition from liquid to solid feed at the time of weaning. An additional objective was to validate the Precision Xtra (Abbott Diabetes Care, Abingdon, UK) calf-side test for determination of BHB in whole blood in calves around weaning, as compared with the gold standard laboratory method. A total of 20 Holstein female calves were randomly assigned at birth to be weaned at 6 wk (n=10) or 8 wk (n=10) of age. Milk replacer (mixed at 150 g/L) was offered at 1.2kg/calf per d in 2 meals until a 1-wk step down, when milk meals were reduced by 50% 1 wk before weaning. Daily measurements included the intakes of starter grain, chopped straw, and water. Weekly measurements included body weight and blood BHB, until 70 d of life. To assess digestive tract development, rumen fluid samples were taken before and after weaning (d 35, 49, and 63) and analyzed for ruminal short-chain fatty acids. Whole blood was collected by jugular venipuncture, and BHB was determined by the Precision Xtra test at calf-side. In addition, serum was separated from a clotted sample, frozen, and stored until laboratory analysis was performed. Laboratory BHB results were correlated with both the Precision Xtra test (r=0.95) and starter intake over 1 d (r=0.89), a 3-d average (r=0.90), and a 7-d average (r=0.90). Additionally, laboratory BHB results were associated with total ruminal volatile fatty acids (r=0.82), ruminal butyrate (r=0.77), and body weight (r=0.69). A receiver operating characteristic curve was created to plot the true positive rate against the false positive rate at 10μmol/L BHB intervals to determine the optimal cut-point of circulating BHB that is predictive of an average starter intake of 1,000 g/d over a 3-d period. The optimal combination of sensitivity (95.7%) and specificity (96.1%) was at 100µmol of BHB/L of blood. A value of 0.2 mmol/L on the Precision Xtra test yielded a sensitivity and specificity of 84.0 and 97.2%, respectively, over the 3-d average period of starter intake. These results show considerable promise for use of the Precision Xtra whole blood BHB test in the decision-making process of determining sufficient starter grain intake and rumen development for a successful transition from liquid to solid feed, and indicate that this test conducted at calf-side is highly accurate.

The objective of this research was to evaluate the usefulness of a novel calf VIGOR assessment tool to measure birth trauma and associations with future health and growth. In addition, pain management therapy using meloxicam injectable solution was evaluated for calves suffering from birth trauma and reduced vigor. A total of 842 heifer and bull calves from 10 commercial dairy herds were enrolled in a randomized, double-blind clinical field trial. At birth, newborn VIGOR was evaluated by the dairy producer to assess the Visual appearance, Initiation of movement, General responsiveness, Oxygenation, as well as heart and respiration Rate of the calf. Subsequently, calves were administered either a 1.0 mL subcutaneous injection of meloxicam or placebo solution. Each calf was measured for growth and assessed using a standardized clinical score for health at 1, 2, 3, and 6 weeks of age. Compared to unassisted calvings, calves born with assistance had lower vigor. Assisted calves treated with meloxicam had improved weight gain in the first week compared to placebo-treated calves. In contrast, treatment with meloxicam resulted in lower gains in observed but unassisted calves. Calves with improved newborn vigor and better health had significantly greater weight gain up to 6 weeks of age. Meloxicam-treated calves had better health from birth to 6 weeks of age. Overall, the calf VIGOR score is a good indicator of trauma at calving. Meloxicam therapy shows promise for improving health and growth, particularly for calves born with assistance.

The objective of this research was to examine the efficacy of supplementing colostrum with sodium bicarbonate for improving passive transfer, health, and growth. An additional objective was to evaluate the effects of calving difficulty on calf vigor. A total of 543 heifer and bull calves from 9 commercial dairy herds were enrolled in this randomized double-blind field trial. At birth, calves were assessed for vigor by the dairy producer, using a prototype calf vigor assessment tool which rated Visual appearance, Initiation of movement, General responsiveness, Oxygenation, and Rates of heartbeat and respiration (VIGOR). Subsequently, calves were fed colostrum supplemented with either 20 g of sodium bicarbonate (SB) or placebo powder. Blood was collected from each calf between 1 and 8 days of age for serum total protein (STP). Each calf was assessed with a standardized clinical score for general health, and measured for growth using a heart girth weight tape at 1, 2, 3, and 6 weeks of age. The findings suggest that calves born with assistance, or that were malpositioned at calving, had lower vigor than those born unassisted. Yet, calf vigor improved with time following birth. Measures from the VIGOR score, including slower responsiveness and a higher heart rate, were associated with reduced health. There was a significant interaction between sex of the calf and SB supplementation of colostrum with STP. Sodium bicarbonate supplementation of colostrum was not significantly associated with improved passive transfer, and had no significant effect on weight gain. Assessment of calf vigor in calves born with assistance may be an important management tool for dairy producers as an indicator that further intervention may be needed to improve health.