Evaluation of a point-of-care electrochemical meter to detect subclinical ketosis and hypoglycaemia in lactating dairy cows

OBJECTIVES

To evaluate and validate a hand-held electrochemical meter (Precision Xtra®) as a screening test for subclinical ketosis and hypoglycaemia in lactating dairy cattle.

DESIGN

Method comparison study using a convenience sample.

PROCEDURE

Blood samples were collected into plain tubes from the coccygeal vessels of 181 Holstein cows at 2-4 weeks of lactation during summer in Iran. Blood β-hydroxybutyrate concentration (BHB) and glucose concentration were immediately measured by the electrochemical meter after applying 20 μL of blood to the reagent strip. Passing-Bablok regression and Bland-Altman plots were used to determine the accuracy of the meter against laboratory reference methods (BHB dehydrogenase and glucose oxidase).

RESULTS

Serum BHB ranged from 0.1 to 7.3 mmol/L and serum glucose ranged from 0.9 to 5.1 mmol/L. Passing-Bablok regression analysis indicated that the electrochemical meter and reference methods were linearly related for BHB and glucose, with a slope estimate that was not significantly different from 1.00. Clinically minor, but statistically significant, differences were present for the intercept value for Passing-Bablok regression analysis for BHB and glucose, and bias estimates in the Bland-Altman plots for BHB and glucose.

CONCLUSION

The electrochemical meter provided a clinically useful method to detect subclinical ketosis and hypoglycaemia in lactating dairy cows. Compared with other method validation studies using the meter, we attributed the improved performance of the electrochemical meter to application of a fixed volume of blood (20 μL) to the reagent strip, use of the meter in hot ambient conditions and use of glucose oxidase as the reference method for glucose analysis.

Evaluation of recombinant P23 protein as a vaccine for passive immunization of newborn calves against Cryptosporidium parvum

Cryptosporidiosis is a zoonotic protozoan disease that affects the gastrointestinal tract of animals and humans. Diarrhoea as the most important indication of the infection leads to high economic losses in livestock industries and is a life threatening infection in immunocompromised individuals. In the absence of the effective drugs, vaccine has an effective role in the prevention of infection. For this purpose we developed a vaccine utilizing recombinant P23 protein and immunized pregnant cows four times from 70 days to parturition every 2 weeks. After parturition, each calf received his dam colostrum and challenged with 1 × 10(7) Cryptosporidium parvum oocysts at 12 h of age. Results showed that in contrast with the control group, the antibody titre in the sera and first milking colostra of the immunized cows significantly increased and calves fed hyperimmune colostrum did not show cryptosporidiosis signs. Moreover, enriched colostrum not only reduced significantly the amount of oocyst excretion but also delayed its onset. Our study showed that recombinant P23 protein could be used for passive immunization of newborn calves against Cryptosporidium parvum.

Effect of orally administered cisapride, bethanechol, and erythromycin on the apparent efficiency of colostral IgG absorption in neonatal Holstein-Friesian calves

Objective

To evaluate the effect of orally administered cisapride, bethanechol, and erythromycin on the absorption of colostral IgG in dairy calves.

Animals

Twenty‐four healthy neonatal Holstein‐Friesian calves.

Procedures

Calves were randomly assigned to one of the following treatments: 0.9% NaCl solution (2 mL, PO; negative control); erythromycin lactobionate (20 mg/kg BW, PO; anticipated to be a positive control); cisapride (0.5 mg/kg BW, PO); bethanechol chloride (0.5 mg/kg BW, PO). Calves were fed 3 L of pooled bovine colostrum containing acetaminophen (50 mg/kg) by suckling and oroesophageal intubation 30 minutes after each treatment was administered. Jugular venous blood samples were obtained periodically after the start of feeding and plasma total IgG, protein, acetaminophen, and glucose concentrations determined. Abomasal emptying rate was assessed by the time to maximal plasma acetaminophen concentration.

Results

Oral administration of cisapride facilitated the absorption of colostral IgG and protein. The effect of cisapride on abomasal emptying rate could not be evaluated because cisapride appeared to interfere with acetaminophen metabolism. Based on the total IgG and total protein concentration‐time relationships, the beneficial effects of cisapride appeared to occur early after oral administration and were transient.

Conclusions and Clinical Importance

Additional studies appear indicated to characterize the effect of cisapride dose on the magnitude and duration of its effect on facilitating the absorption of colostral IgG and protein. Identification of a nonantimicrobial method for increasing abomasal emptying rate, such as cisapride, will potentially provide a practical and effective method for facilitating transfer of passive immunity in colostrum‐fed dairy calves.

Effects of probiotics supplementation in daily milk intake of newborn calves on body weight gain, body height, diarrhea occurrence and health condition

The effects of probiotic administration were studied in an experiment, using 120 newborn calves. Calves were randomly assigned to two experimental groups (sixty calves for each group) and probiotic (0.25 g h(-1) day(-1)) was added in their daily milk intake until 90 days of age. After the first week, all calves (including control group) received starter ration containing 21.0% crude protein and 3.0% crude fat. Body weight gain, body height and general health condition of all calves were observed at day 30, 60 and 90. Also condition of feces was examined daily and the occurrence of diarrhea was recorded throughout the experiment. Mean values of weight gain during three successive months for treatment and control groups were 57.52 and 50.58 kg, respectively. Body weight gained was not significantly different for first and second mo between treatment and control groups (16.9 and 33.87 vs. 14.49 and 33.07 for fist and second months in treatment and control groups, respectively). However, these values were significantly different (p < 0.001) between treatment (57.52) and control (50.58) groups third months of age. Diarrhea was observed in 35 calves of control group, which was higher than 11 cases in calves treated with probiotic (p < 0.001). The body height values of control and treatment groups in three successive months were 5.49, 10.82 and 15.00 cm for control and 5.44, 9.25 and 15.75 cm for treatment groups in first, second and third mo, respectively, which showed no significant difference between two groups during this study. The results of this study indicated that present probiotic compound have beneficial effects, especially on the third month of age in rearing calves.