Validation of handheld meters to measure blood l-lactate concentration in dairy cows and calves

In cattle, blood lactate was measured in various conditions such as parturition and dystocia. To our knowledge, to date, no handheld device has been validated for the use in cows and only one handheld device was validated for the use in calves. When determining plasma lactate concentrations blood samples have to be processed carefully. Sodium fluoride was recommended to inhibit glycolysis and to stabilize plasma lactate concentrations during transport. However, its effect on measurements conducted with electrochemical meters has not been studied. The objectives of 3 experiments were to study factors influencing measures of L-lactate in dairy cows (e.g., different anticoagulants, different methods) and to validate a handheld device (Lactate Scout, SensLab GmbH, Leipzig, Germany) to determine L-lactate concentration in dairy cows and calves. In a first approach, blood samples from 49 cows were analyzed by 2 different laboratories. Measures of L-lactate concentration were correlated between the different laboratories in both lithium heparin plasma (r=0.98) and sodium fluoride plasma (r=0.99). In a second approach, these samples were analyzed using 3 methods [Lactate Scout, Biosen C_line (EKF Diagnostics GmbH, Barleben, Germany), and commercial laboratory]. Concentrations of L-lactate measured in lithium heparin did not differ when analyzed with the Lactate Scout (0.99±0.35 mmol/L), the Biosen C_line (0.81±0.26 mmol/L), or the laboratory (1.0±0.36 mmol/L). Concentrations of L-lactate measured in sodium fluoride, however, were higher when analyzed with the Lactate Scout (1.85±0.66 mmol/L) compared with those measured with the Biosen C_line (0.92±0.37 mmol/L) and by the commercial laboratory (0.72±0.45 mmol/L). In the second and third experiments, blood samples from 173 cows and 106 calves were analyzed using the 3 methods (Lactate Scout, Biosen C_line, and commercial laboratory). L-Lactate concentrations measured with the 3 methods were correlated (cows: Lactate Scout vs. Biosen C_line: r=0.97, Lactate Scout vs. laboratory 1: r=0.98, Biosen C_line vs. laboratory 1: r=0.99; calves: Lactate Scout vs. Biosen C_line: r=0.97, Lactate Scout vs. laboratory 1: r=0.98, Biosen C_line vs. laboratory 1: r=0.99). In conclusion, Lactate Scout and Biosen C_line measure blood L-lactate concentrations reliably compared with a commercial laboratory as the reference method in dairy cows and calves. However, attention needs to be paid to the choice of anticoagulant used in sample collection

Presence of Escherichia coli, Trueperella pyogenes, α-hemolytic streptococci, and coagulase-negative staphylococci and prevalence of subclinical endometritis

Subclinical endometritis (SCE) has a severe negative effect on reproductive performance of dairy cows. Different studies have shown a wide variety of cut points for the polymorphonuclear neutrophilic leukocyte (PMNL) percentage to define SCE and differing sampling times. Possible risk factors for SCE, such as low body condition score, hyperketonemia, and increased haptoglobin concentrations have been demonstrated. The aim of this study was to determine the relationship between bacterial findings in the uterus and PMNL in the early postpartum period and to compare 2 classification schemes for the diagnosis of SCE. Cytological and bacteriological samples from the uterus were taken from 149 cows at 2 consecutive times postpartum [10±1 and 24±1d in milk (DIM)] and additionally, 131 cows were sampled at 21 to 27 DIM. For sample collection, the cytobrush technique was used and vaginal discharge was examined by vaginoscopy. Polymorphonuclear neutrophilic leukocyte cut points were set at 5, 10, and 18%. Cows positive with α-hemolytic streptococci at 10±1 DIM had significant higher PMNL percentages at 21 to 27 DIM and greater median days to pregnancy (193.5d) than cows not infected (123.0d). Cows with Trueperella pyogenes at 10±1 DIM had higher odds (5.2) of having more than 18% PMNL at 21 to 27 DIM compared with cows without infection. Escherichia coli had no effect on the prevalence of SCE regardless of the cut point. Primiparous cows with more than 18% PMNL had greater median days to pregnancy (144.5 d) than cows with less than 5% (80.0d) or cows between 5 and 18% PMNL (68.0d). Cows between 5 and 18% PMNL or 10 and 18% PMNL showed the best reproductive performance. The results demonstrate that an early infection with α-hemolytic streptococci increased the PMNL percentage 2wk later and that 18% PMNL at 21 to 27 DIM was a predictive cut point for primiparous cows to diagnose animals with or without SCE

Comparison of Immediate Blanket Treatment versus a Delayed Pathogen-Based Treatment Protocol for Clinical Mastitis Using an On-Farm Culture Test at a Commercial German Dairy Farm

The objective of this study was to compare immediate intramammary antimicrobial treatment of mild and moderate cases of clinical mastitis (CM) with a selective treatment protocol based on on-farm culture results using Accumast®. The study was conducted at a 2600 cow commercial farm in Northeast Germany. Using a randomized design, mild and moderate clinical mastitis cases were assigned to either the blanket therapy (BT) or pathogen-based therapy (SELECT) group. Overall, 468 cases were used for final analyses (BT = 236; SELECT = 232). The percentage of cases assigned to the blanket and pathogen-based groups that received intramammary therapy were 100 and 69.9%, respectively. Implementation of a pathogen-based treatment protocol for mild and moderate CM cases resulted in no significant difference in post-event milk production, somatic cell count, survival to 30 d, and days spent in the hospital compared with a blanket therapy protocol. Cows in the SELECT group had reduced odds of being culled within 60 d post CM (odds ratio = 0.54; 95% CI = 0.31–0.93; p = 0.027). The use of a pathogen-based treatment protocol using an on-farm culture system has the potential to efficiently reduce antimicrobial use without negative effects on health

Evaluation of transrectal examination of cervical diameter by palpation in dairy cows

The objective of the study was to evaluate the reliability of a manual assessment of cervical diameter through palpation. In an in vivo trial, 64 Holstein-Friesian cows between 2 and 5d in milk (DIM) and between 21 and 27 DIM were examined by transrectal palpation by 3 investigators. For calculation of sensitivity and specificity, ultrasound-generated measurements were used as reference standard; a cervix >7.5 cm was categorized as large. The Pearson coefficient of correlation between the results of the 3 investigators and ultrasound-generated measurements was moderate (r=0.71, 0.74, and 0.51). The estimates generated by palpation by the 3 different investigators did not differ and were similar to measurements obtained by ultrasound. The coefficient of variation (CV) between the investigators and ultrasound was high (20.9, 18.7, and 32.0%). The mean difference between the investigators and the ultrasound was 0.60 cm (95% confidence interval: -2.4 to 3.6). Sensitivity was 28.6, 42.9, and 42.9%, and specificity was 100, 96.2, and 92.6% for the ability of the 3 investigators, respectively, to detect the 7.5-cm cutoff by palpation. Overall sensitivity and specificity for all 3 investigators, considering ultrasound as the reference, were 37.5 and 96.2%, respectively. In vitro, 24 wooden cylinders were used to represent cervical diameter and to examine the reliability, as well as sensitivity and specificity, of manual assessment of different diameters. The Pearson coefficient of correlation between the results of the investigators (n=11) and the actual diameters of the cylinders was 0.78. The CV between the investigators and the cylinders was 27.8%. The variation in the results was greater for cylinders with a larger diameter (3.5-cm diameter: mean ± standard deviation = 2.6 ± 0.9 cm; 10.5-cm diameter: mean ± standard deviation = 13.2 ± 4.0 cm). The estimate obtained by palpation for the 7.5-cm cylinder was 7.4 ± 2.1cm. Sensitivity was 79.4% and specificity 92.5%. After training one group of investigators, sensitivity and specificity improved to 85.9 and 94.4%, respectively. Transrectal palpation of the cervical diameter shows moderate repeatability and correlation and high variation between the investigators and the reference standards. Variability increased with larger diameters

Luteal Presence and Ovarian Response at the Beginning of a Timed Artificial Insemination Protocol for Lactating Dairy Cows Affect Fertility: A Meta-Analysis

Progesterone (P4) concentration during follicular growth has a major impact on fertility response in timed artificial insemination (TAI) protocols. Luteal presence at the beginning of a TAI protocol and ovarian response after the first gonadotropin-releasing hormone (GnRH) injection (G1) affect P4 concentration and subsequently pregnancy per artificial insemination (P/AI). A systematic review of the literature and meta-analytical assessment was performed with the objective of evaluating the magnitude of the effect of luteal presence and ovarian response at the beginning of a TAI protocol on P/AI in lactating dairy cows. We considered only studies using synchronisation protocols consisting of GnRH and prostaglandin F (2 alpha). The time interval between G1 and prostaglandin F (2 alpha) (PGF (2 alpha)) had to range from 5 to 7 d. The time interval between the PGF (2 alpha) injection and G2 had to range from 48 to 72 h. We used 28 controlled experiments from 27 published manuscripts including 16,489 cows with the objective of evaluating the effect size of having a functional corpus luteum (CL) at G1 on P/AI. Information regarding ovulatory response after G1 was available for 5676 cows. In a subset of cows (n = 4291), information was available for luteal presence and ovulatory response at the initiation of the TAI protocol. A functional CL at G1 increased (p < 0.001) the relative risk of conceiving (RR (relative risk) = 1.32; 95% CI = 1.21-1.45) in lactating dairy cows. Ovulation after G1 increased (p < 0.001) the relative risk of conceiving (RR = 1.29; 95% CI = 1.20-1.38) in lactating dairy cows. The effect of ovulatory response on P/AI after G1 was affected by luteal presence at G1. In summary, there was a clear benefit on P/AI for cows starting a TAI protocol with a functional CL (+10.5 percentage units) and cows ovulating at the beginning of a TAI protocol (+11.0 percentage units)

a meta-analysis

The objective of the conducted meta-analysis was to assess the efficacy of the treatment of bovine endometritis with PGF(2α) by statistical means. Postpartum uterine infections have a high prevalence and a very negative effect on reproductive performance in dairy cattle. Because of a wide discordance between research results, a meta-analysis of the efficacy of the treatment of bovine endometritis with PGF(2α) was conducted. A comprehensive literature search was performed using online databases to reveal a total of 2,307 references. In addition, 5 articles were retrieved by reviewing citations. After applying specific exclusion criteria and evaluating specific evidence parameters, 5 publications, comprising 6 trials, were eligible for being analyzed by means of meta-analysis. Data for each trial were extracted and analyzed using meta-analysis software Review Manager (version 5.1; The Nordic Cochrane Centre, Copenhagen, Denmark). Estimated effect sizes of PGF(2α) were calculated on calving to first service and calving to conception interval. Prostaglandin F(2α) treatment of cows with chronic endometritis had a negative effect on both reproductive performance parameters. Heterogeneity was substantial for calving to first service and calving to conception interval [I(2) (measure of variation beyond chance)=100 and 87%, respectively]; therefore, random-effects models were used. Sensitivity analysis as well as subgroup analysis showed that the performance of randomization was influential in modifying effect size of PGF(2α) treatment. The funnel plot illustrated a publication bias toward smaller studies that reported a prolonged calving to conception interval after a PGF(2α) treatment. We conclude that the investigation of this subject by means of meta-analysis did not reveal an improvement of reproductive performance of cows with endometritis after treatment with PGF(2α). Furthermore, there is a shortage of comparable high quality studies investigating reproductive performance after PGF(2α) treatment of cows with chronic endometritis

Comparison of ambient temperature, relative humidity, and temperature-humidity index between on-farm measurements and official meteorological data

The objectives of the study were to compare the climate conditions of 7 dairy farms with the climate recorded at the closest official meteorological station. Specifically, we set out to compare the ambient temperature, relative humidity, and the resulting temperature-humidity index (THI) from 7 different barns with those data obtained from the closest official meteorological stations and to compare the climate conditions between 4 different locations within 1 barn. Measures of correlation and agreement demonstrated that climate conditions differ significantly between the barn and the corresponding official meteorological stations as well as between 4 different locations inside 1 barn. The ambient temperature was higher (6.4 ± 3.6°C) in the barn than at the official meteorological station. The relative humidity was higher at the official meteorological station (0.2 ± 7.2%) than in the barn. The THI was higher (11.1 ± 6.5) in the barn than at the official meteorological station. Days with an average THI ≥ 72 were 64 and 4 out of 756 experimental d in the barn and at the official meteorological station, respectively. Also, in a comparison of 7 different barns, ambient temperature and THI were significantly higher than at the closest corresponding official meteorological station. These results indicate that climate conditions should be obtained from on-farm measurements to evaluate potential heat stress and to develop effective measures to abate heat stress of dairy cows

quality and comparability of clinical trials investigating the efficacy of prostaglandin F2α for the treatment of bovine endometritis

The objective of this study was to evaluate the quality and comparability of published literature, and to summarize the effect of prostaglandin F(2α) (PGF(2α)) for the treatment of endometritis. It has been postulated that there is a dearth of high-level evidence-based research results in veterinary medicine. Also, there is a marked variation in the quality of studies in veterinary and animal science. Post-partum uterine infections occur commonly in dairy cattle and are reported to have a negative impact on reproductive performance. A comprehensive literature search was conducted utilizing online databases revealing a total of 2723 references. After applying specific exclusion criteria, a total of 68 trials were eligible for further analysis. These articles were evaluated utilizing specific parameters listed in an evaluation form such as randomization and the involvement of control groups. The analysis revealed that more than half of the trials (51·5%) were at least 20 years old. Furthermore, we found that about one third (36·8%) of all trials were controlled and randomized, while 3 of those (4·4%) were also blinded. Of those trials which calculated a calving-to-conception interval (n=30), 50% of the authors claimed an improvement, which was statistically significant in 23·3% of the cases. We conclude that there is a wide discrepancy between research results investigating the efficacy of PGF(2α)