S. Borchardt

Effect of insemination after estrous detection on pregnancy per artificial insemination and pregnancy loss in a Presynch-Ovsynch protocol: A meta-analysis

Presynchronization of cows with 2 injections of prostaglandin administered 14d apart (Presynch-Ovsynch) is a widely adopted procedure to increase pregnancy per artificial insemination (P/AI) for the first service. In a Presynch-Ovsynch protocol, 2 different management strategies can be observed. Either all cows receive timed artificial insemination (onlyTAI) or cows detected in estrus after the second PGF2α injection are inseminated and the remaining cows without signs of estrus will be subject to timed AI (EDAI+TAI). A systematic review of the literature was performed with the objective to evaluate the effect of insemination after estrous detection during a Presynch-Ovsynch protocol for the first service on fertility in lactating dairy cows. Two statistical approaches were conducted using either a fixed or a random effects meta-analysis based on the heterogeneity among the experimental groups. Reproductive outcomes of interest were P/AI measured on d32 (d 28 to 42) and pregnancy loss between d32 and 60 (d 42 to 74) of gestation. In approach 1, 3 randomized controlled studies including 1,689 cows with the primary objective to evaluate the effect of insemination after estrous detection in a Presynch-Ovsynch protocol were used. The incorporation of insemination after estrous detection decreased the odds of pregnancy by 35% [odds ratio=0.65; 95% confidence interval (CI)=0.53-0.80] on d32 after AI using a fixed effects model. We detected no effect on pregnancy loss on d60 of gestation (odds ratio=0.88; 95% CI=0.55-1.43). There was no heterogeneity among the 3 studies regarding P/AI and pregnancy loss. In approach 2, cows from approach 1 and cohorts from another 17 experimental groups including 8,124 cows submitted to first AI using a Presynch-Ovsynch protocol were used. Information regarding pregnancy loss was available for 5,200 cows. In the random effects model, the overall proportion of P/AI was 30.9% (95% CI=26.71-35.28; n=2,400) and 41.7% (95% CI=39.76-42.01; n=7,413) on d32 after AI for EDAI+TAI and onlyTAI, respectively. The overall proportion of pregnancy loss was 11.7% (95% CI=6.11-18.8; n=1,811) and 9.6% (95% CI=6.37-13.33; n=3,389) on d60 after AI for EDAI+TAI and onlyTAI, respectively. We observed substantial heterogeneity among the experimental groups regarding P/AI and pregnancy loss. In summary, there was a benefit on P/AI for cows with 100% TAI after completing a Presynch-Ovsynch protocol.

Randomized, controlled clinical trial on the efficacy of nonsteroidal antiinflammatory drugs for the treatment of acute puerperal metritis in dairy cows

The objective of this study was to assess the efficacy of ketoprofen compared with ceftiofur hydrochloride for the treatment of acute puerperal metritis (APM). Specifically, we set out to compare the incidence of extended treatment (extT) between treatment groups, to determine the prevalence of purulent vaginal discharge (PVD) and milk yield on the first 3 milk tests postpartum, and to analyze reproductive performance of cows treated with ketoprofen or ceftiofur. Cows with rectal temperature ≥39.5°C and reddish-brown fetid vaginal discharge within the first 10 d in milk (DIM) were diagnosed with APM. Day of enrollment and first day of treatment was considered study day 1. Rectal temperature was recorded daily until study day 7. A total of 610 dairy cows with APM were enrolled in this randomized clinical trial. Cows meeting the inclusion criteria were allocated to treatment with ketoprofen (3mg/kg of body weight, n=300) or treatment with ceftiofur (1mg/kg of body weight, n=310) on study days 1, 2, and 3. Cows that showed rectal temperature ≥39.5°C between study days 4 and 7 received an extT with ceftiofur for 3 (ketoprofen group) or 2 (ceftiofur group) more days. Cows were examined with the Metricheck device (Simcro, Hamilton, New Zealand) between DIM 21 and 40, and vaginal discharge was categorized on a 5-point scale according to the presence of pus. Cows with a score ≥2 were classified as having PVD. Fifty-two cows (35 from ketoprofen group, 17 from ceftiofur group) were excluded from analysis due to missing protocol compliance (n=37) or concurrent disease (n=15). Cows treated with ketoprofen were more likely to have an extT than cows treated with ceftiofur (61 vs. 31%). Prevalence of PVD did not differ between the 2 treatment groups (ketoprofen, 56%; ceftiofur, 53%). Cows, however, that needed an extT after the initial 3-d treatment were more likely to develop PVD than cows without extT (64 vs. 46%). Treatment group did not affect milk yield (ketoprofen group, 35.5±0.4kg; ceftiofur group, 35.2±0.3kg), first artificial insemination pregnancy risk (ketoprofen group, 20% vs. ceftiofur group, 25%), median days to first artificial insemination [ketoprofen group, 73 d, 95% confidence interval (CI): 70-75 d vs. ceftiofur group, 75 d, 95% CI: 72-76 d] and median days to pregnancy (ketoprofen group, 144 d, 95% CI: 132-158 d vs. ceftiofur group, 133 d, 95% CI: 119-153 d). These results indicate that although cows initially treated with ketoprofen were more likely to receive extT, fewer doses of ceftiofur (1.83) were required compared with cows initially treated with ceftiofur (3.63). Moreover, the prevalence of PVD was not increased and milk yield and reproductive performance were not negatively affected by the initial treatment with ketoprofen.

Evaluation of prostaglandin F2α versus prostaglandin F2α plus gonadotropin-releasing hormone as Presynch methods preceding an Ovsynch in lactating dairy cows: A meta-analysis

Presynchronization of cows with 2 injections of prostaglandin administered 14 d apart (Presynch-Ovsynch) is a widely adopted procedure to increase pregnancy per artificial insemination (P/AI) at first service. Recently, a presynchronization protocol including GnRH and PGF2α (Double-Ovsynch; GnRH, 7 d, PGF2α, 3 d, GnRH) followed 7 d later by an Ovsynch protocol was introduced to overcome the limitations of PGF2α-based protocols for presynchronization of anovular cows and to precisely set up cows on d 7 of the estrous cycle when the Ovsynch is initiated. A systematic review of the literature and a meta-analytical assessment was performed with the objective to compare the reproductive performance of lactating dairy cows presynchronized with these 2 protocols for the first timed AI (TAI) considering parity-specific effects. A fixed or a random effects meta-analysis was used based on the heterogeneity among the experimental groups. Reproductive outcomes of interest were P/AI measured on d 32 (28-42) and pregnancy loss between d 32 and 60 (42-74) of gestation. A total of 25 articles with 27 experimental groups from 63 herds including 21,046 cows submitted to first TAI using either a Presynch-Ovsynch or a Double-Ovsynch protocol were reviewed. Results for P/AI were then categorized by parity if available. Information was available for P/AI for 7,400 and 10,999 primiparous and multiparous cows, respectively. Information regarding pregnancy loss was available for 7,477 cows. In the random effects model for all cows, the overall proportion of P/AI was 41.7% [95% confidence interval (CI): 39.1-44.3; n = 8,213] and 46.2% (95% CI: 41.9-50.5; n = 12,833) on d 32 after TAI for Presynch-Ovsynch and Double-Ovsynch, respectively. In the random effects model for primiparous cows, the overall proportion of P/AI was 43.4% (95% CI: 36.2-47.7; n = 2,614) and 51.4% (95% CI: 47.4-55.4; n = 4,786) on d 32 after TAI for Presynch-Ovsynch and Double-Ovsynch, respectively. In the random effects model for multiparous cows, the overall proportion of P/AI was 39.2% (95% CI: 36.2-42.3; n = 3,411) and 41.4% (95% CI: 36.4-46.4; n = 7,588) on d 32 after TAI for Presynch-Ovsynch and Double-Ovsynch, respectively. The overall proportion of pregnancy loss was 11.3% (95% CI: 7.6-15.7; n = 3,247) and 11.7% (95% CI: 9.3-14.3; n = 4,230) on d 60 after AI for Presynch-Ovsynch to and Double-Ovsynch, respectively. Substantial heterogeneity existed among the experimental groups regarding P/AI and pregnancy loss. In summary, a benefit was detected for P/AI in primiparous cows presynchronized with a Double-Ovsynch protocol for the first TAI, but this benefit was not observed in multiparous cows.

Antibiotic treatment of metritis in dairy cows—A meta-analysis

The objective of this meta-analysis was to assess the efficacy of the treatment of bovine metritis with common antibiotic and nonantibiotic treatment options. Acute puerperal metritis, a systemic and potentially painful illness with rectal temperature >39.5°C and signs of toxemia due to an infection of the uterus, occurs within 21 d after parturition. Because of the infectious nature, antibiotics are considered beneficial for the treatment of acute puerperal metritis. Each use of an antimicrobial drug, however, is associated with selective pressure for eventual emergence of resistant bacteria. The 23 trials evaluated in the course of a previously conducted systematic review were the basis for meta-analytic investigations. Selected trials were screened regarding their eligibility for the following investigations: (1) comparison of different antibiotic treatments with respect to metritis prevalence at time of re-examination, (2) efficacy of ceftiofur treatment with respect to metritis prevalence at time of re-examination, (3) comparison of efficacy of antibiotic versus nonantibiotic drugs with respect to metritis prevalence at time of re-examination, and (4) equivalence assessment of treatment effects on reproductive performance measures. Where at least 3 trials had investigated the same outcome variable and met the inclusion criteria (inclusion of a control or reference group diagnosed with metritis; reporting means and standard deviation in case of continuous data), meta-analytic investigations were carried out. Due to a shortage of comparable studies, we could not conduct investigations (1) and (3). Ceftiofur treatment of 828 metritic cows was associated with a decrease in the prevalence of metritis following treatment in comparison to 804 untreated cows. In conclusion, meta-analytic investigations uncovered a need for more high-quality studies. Furthermore, a positive effect of the most commonly used antibiotic drug, ceftiofur, for the treatment of bovine metritis could be shown. A comparison with other antibiotic or nonantibiotic treatment options could not be made.

Hypocalcemia—Cow-level prevalence and preventive strategies in German dairy herds

Hypocalcemia around calving is considered a gateway disease that can lead to health disorders and decreased milk production. The objective of this cross-sectional study was to evaluate the prevalence of clinical and subclinical hypocalcemia 0 to 48 h after calving. Blood samples were drawn from 12 animals of each dairy farm (n = 115) and analyzed for serum calcium, magnesium, and phosphorus concentration. Cows not affected clinically but with a serum calcium concentration below 2.0 mmol/L were characterized as subclinical hypocalcemic animals. Recumbent cows with a serum calcium concentration below 2.0 mmol/L were defined as cows suffering from clinical milk fever. Herds were classified into negative (0 to 2/12), borderline (3 to 5/12), and positive (≥6/12) according to the number of animals with hypocalcemia. Strategies to control hypocalcemia were documented. Prevalence of clinical milk fever was 1.4, 5.7, and 16.1% for second, third, and ≥fourth parity cows, respectively. None of the cows in first lactation were suffering from clinical milk fever. Based on the threshold of 2.0 mmol/L, 5.7, 29.0, 49.4, and 60.4% of cows in first, second, third, and ≥fourth lactation were suffering from subclinical hypocalcemia, respectively. Fourteen, 51, and 50 herds were classified as negative, borderline, and positive, respectively. A positive association was observed between serum calcium and serum phosphorus concentration. Serum calcium and magnesium concentration were negatively associated. Only 50 of 115 farms had a control strategy implemented to avoid hypocalcemia. Most common was the use of oral calcium products (40/115 herds), followed by feeding of anionic salts in the close-up diet (10/115 herds). These results indicate that the prevalence of clinical and subclinical hypocalcemia in German dairy herds was high and that an active control strategy was not implemented on all farms. The negative association between calcium and magnesium warrants further research regarding the physiological regulation of these 2 minerals around parturition.

Effect of a phase I Coxiella burnetii inactivated vaccine on body temperature and milk yield in dairy cows

Q fever is a zoonotic disease caused by Coxiella burnetii. The pathogen is prevalent in ruminants (goats, sheep, cows), which are the main sources of human infection. In the cattle industry around the world, animal (15 to 20%) and herd (38 to 72%) level prevalences of C. burnetii are high. Vaccination of ruminants against Q fever is considered important to prevent spreading of the disease and risk of infection in humans. However, published information on side effects of the Q fever vaccination under field conditions is limited for cows. The objective of this study was to investigate the effect of the phase I C. burnetii inactivated vaccine Coxevac on body temperature and milk yield in dairy cows. In 2 experiments, a total of 508 cows were randomly divided into 2 groups to determine the effect of first vaccination on body temperature and milk yield. The C. burnetii serostatus of all cows was tested before vaccination with an indirect ELISA. The first experiment took place in the teaching and research barn of the Clinic of Animal Reproduction at the Freie Universität Berlin. Temperature was measured vaginally in 10 cows in a crossover design. The second experiment was conducted on a commercial dairy farm. Milk yield of 498 cows was measured 1 wk before and 1 wk after vaccination. In a subset of 41 cows, temperature was measured rectally. In both experiments, body temperature increased significantly after vaccination (1.0 ± 0.9°C and 0.7 ± 0.8°C). A significant difference was also found in body temperature between vaccinated and control cows. Thirty percent of the vaccinated animals in experiment 1 showed reversible swelling at the injection site as a reaction to the vaccination. The results indicate that vaccination against Q fever causes a transient increase of body temperature that peaks in the first 12 to 24h and declines after that. In experiment 2, vaccinated cows (26.8 ± 0.39 kg/d) produced significantly less milk than did control cows (28.2 ± 0.44 kg/d) 7d after first vaccination. The cumulative milk loss after first vaccination was influenced by an interaction between C. burnetii serostatus and average milk yield 7d before first vaccination. This was considered as part of the physiological immune response. Three out of 10 vaccinated animals in experiment 1 showed painful swelling of the skin at the injection site, which had a maximum size of 14.0 × 14.0 × 1.1cm. In conclusion, a transient increase of body temperature and a decrease in milk yield is prevalent after Coxevac vaccination.

Randomized clinical trial to evaluate the efficacy of prostaglandin F2α to treat purulent vaginal discharge in lactating dairy cows

The objectives of this study were (1) to assess the effect of purulent vaginal discharge (PVD) on reproductive performance using a 4-point vaginal discharge score (VDS) and (2) to evaluate the effect of PGF2α treatment in cows with PVD on reproductive performance. Holstein cows (n = 2,473) from 1 commercial dairy farm had their vaginal discharge scored at 32 ± 3 d in milk (DIM) using a 4-point scale. Cows were also scored for body condition score and had their ovaries examined using transrectal ultrasound. A VDS-2 or greater was used to define PVD. Cows with PVD were assigned to receive 2 doses of 500 µg of PGF2α analogue (n = 277; Cloprostenol; PGF Veyx forte, Veyx Pharma Ltd., Schwarzenborn, Germany) 14 d apart (odd ear tag number) or remained untreated (n = 272; even ear tag number). All cows not detected in estrus at 90 ± 3 DIM were enrolled into a timed artificial insemination (AI) protocol. The effect of VDS and the effect of PGF2α in cows with PVD on reproductive performance were evaluated separately. First service conception risk (FSCR), time to first AI, and time to pregnancy were used as indicators for reproductive performance. Data were analyzed with Coxs regression and mixed logistic models. The prevalence of PVD was 22.2% (548/2,473). We detected an interaction of parity and VDS for FSCR and time to pregnancy. In primiparous cows, VDS had no effect on FSCR and time to pregnancy. In multiparous cows, VDS had an effect on FSCR and time to pregnancy. Multiparous cows having a VDS-2 or a VDS-3 had decreased odds of pregnancy at first AI compared with cows having a VDS-0. Multiparous cows with VDS-1 or VDS-3 had a decreased hazard of conceiving within 200 DIM. The treatment effect of PGF2α was conditional on parity. In primiparous animals with PVD without a corpus luteum present at 32 DIM, treatment with PGF2α reduced FSCR. Irrespective of the presence of a corpus luteum, treatment with PGF2α decreased the hazard of conceiving within 200 DIM in primiparous cows. Although multiparous cows with PVD treated with PGF2α had increased odds of pregnancy at first AI, no treatment effect was observed on the hazard of conceiving within 200 DIM. Our results do not support the blanket use of PGF2α as a treatment option in postpartum dairy cows having PVD.

Short communication: Associations between blood glucose concentration, onset of hyperketonemia, and milk production in early lactation dairy cows

The objectives of this study were to describe the associations between hypoglycemia and the onset of hyperketonemia (HYK) within the first 6 wk of lactation, to evaluate the effects of body condition score at calving on glucose concentration, and to study the effects of hypoglycemia on milk production. A total of 621 dairy cows from 6 commercial dairy farms in Germany were enrolled between 1 and 4 d in milk (DIM). Cows were tested twice weekly using an electronic handheld meter for glucose and β-hydroxybutyrate (BHB), respectively, for a period of 42 d. Hypoglycemia was defined as glucose concentration ≤2.2 mmol/L. Hyperketonemia was defined as a BHB concentration ≥1.2 mmol/L. The onset of HYK was described as early onset (first HYK event within the first 2 wk postpartum) and late onset (first HYK event in wk 3 to 6 postpartum). The effect of ketosis status on blood glucose within 42 DIM was evaluated using a generalized linear mixed model. No effect was observed of HYK on glucose concentration in primiparous cows. Multiparous cows with early-onset HYK had a lower glucose concentration (-0.21 mmol/L) compared with nonketotic cows. Overall, primiparous cows had a lower prevalence and incidence of hypoglycemia than multiparous cows. Hypoglycemia in multiparous cows was associated with higher first test-day milk production and 100 DIM milk production. In conclusion, hypoglycemia mainly occurred in multiparous cows with early-onset HYK, whereas primiparous cows were at a lower risk for hypoglycemia.

Evaluation of ear skin temperature as a cow-side test to predict postpartum calcium status in dairy cows

Subclinical hypocalcemia is considered a gateway disease that increases susceptibility to other metabolic and infectious diseases in transition dairy cows. In the absence of a cow-side test, however, it is difficult to identify hypocalcemic cows. The objective of this study was to evaluate ear skin temperature as a diagnostic predictor of serum calcium concentration. We conducted a cross-sectional study on 7 commercial dairy farms, involving 251 cows 0 to 48h after calving. Skin temperature of the ears (STEar) was scored manually by palpating both ears. An infrared thermometer was used to measure ear temperature, skin temperature on the coxal tuber (STCox), and ambient temperature. Rectal temperature was measured using a digital thermometer. A blood sample was drawn to determine serum calcium concentration. Hypocalcemia was defined as serum calcium below 2.0mmol/L, irrespective of clinical symptoms. Serum calcium concentration <2.0mmol/L in connection with clinical symptoms was defined as clinical milk fever; serum calcium concentration <2.0mmol/L without clinical symptoms was defined as subclinical hypocalcemia. Multivariate analysis using the GENLINMIXED procedure and receiver operating characteristic analysis were performed to evaluate whether serum calcium concentration could be predicted using ear temperature and other temperature estimates. The prevalence of hypocalcemia was 3.3, 27.3, 32.8, and 69.6% for cows in first, second, third, and fourth or greater lactation, respectively. None of the cows in first and second lactation had clinical milk fever. The prevalence of clinical milk fever was 6.0 and 20.3% for cows in their third and fourth or greater lactation, respectively. A decrease in ear temperature of 0.39°C [95% confidence interval (CI): 0.25-0.54] was associated with a decrease of 0.1mmol/L in serum calcium concentration. Ambient temperature, however, was a major confounder for ear temperature. With an increase in ambient temperature of 1°C, STEar rose by 0.78°C (95% CI: 0.67-0.90). Hypothermia was more pronounced in clinical milk fever (median 21.8°C; interquartile range 14.7-27.0°C) compared with subclinical hypocalcemia (median 27.6°C, interquartile range 22.1-30.8°C). All temperature estimates had only accurate test characteristics based on their area under the curve for prediction of subclinical hypocalcemia (area under the curve for STEar, STCox, and rectal temperature were 0.641, 0.668, and 0.606, respectively) when cows with clinical milk fever were excluded. Although ear temperature has been associated with serum calcium concentration, ear temperature cannot be recommended for diagnosis of subclinical hypocalcemia.

Association of postpartum hypocalcemia with early-lactation milk yield, reproductive performance, and culling in dairy cows

Periparturient hypocalcemia is frequently observed and considered as a gateway disease that is associated with various health issues. The objective of this study was to evaluate the association of hypocalcemia with early-lactation milk yield, reproductive performance, and culling across a large number of different managerial systems. A prospective cohort study was conducted based on a convenience sample of 125 dairy herds from 8 federal states of Germany between February 2015 and August 2016. A blood sample was drawn from 1,709 animals within 48 h after parturition and analyzed for serum calcium concentration. After discarding cows (n = 283) with missing data, a total of 1,426 cows were considered for final analyses. The median time from calving to sampling was 14.0 h (interquartile range = 5.0-24.9 h). For each herd, a record of the herd management software was requested 150 d after the last cow was sampled. Serum calcium concentration of each cow was associated with early-lactation milk yield (Dairy Herd Improvement Association equivalent test 1 to 3), reproductive performance [days in milk (DIM) at first artificial insemination (AI), pregnancy at first AI, time to pregnancy within 150 DIM], and culling (until 60 DIM) data. Generalized linear mixed models were used to analyze continuous or categorical data. Shared frailty models were used for time to event data. Five different thresholds were used to define hypocalcemia. Thresholds ranged from 1.8 to 2.2 mmol/L using 0.1-mmol/L increments. Clinical hypocalcemia was defined as serum calcium concentration <2.0 mmol/L in combination with clinical signs (e.g., recumbency). The effect of hypocalcemia on milk yield was conditional on parity. In primiparous cows a serum calcium concentration <2.0 mmol/L (6.4% of cows were below this threshold) had no effect on milk production, whereas there was a tendency for multiparous cows with a serum calcium concentration <2.1 mmol/L (63.2% of cows were below this threshold) to produce 0.80 kg/d more milk compared with multiparous cows at or above the threshold. Multiparous cows suffering from clinical hypocalcemia produced 2.19 kg/d less milk compared with normocalcemic cows in early lactation. Calcium status was not associated with days to first insemination. Cows with a serum calcium concentration <1.9 mmol/L (34.6% of cows below this threshold) had decreased odds (odds ratio = 0.56) of pregnancy at first AI. A serum calcium concentration <1.8 mmol/L (24.1% of cows below this threshold) had a significant effect on time to pregnancy. Compared with animals with a serum calcium concentration ≥1.8 mmol/L, the hazard of becoming pregnant within 150 DIM was reduced when cows had a serum calcium concentration <1.8 mmol/L (hazard ratio = 0.68). Cows with a serum calcium concentration <2.0 mmol/L (44.3% of cows were below this threshold) had a 1.69 times greater hazard of being culled within the first 60 DIM compared with normocalcemic animals. The present study shows that the association of hypocalcemia with milk yield was conditional on parity and serum calcium concentration measured once within 48 h after calving. Considering reproductive performance and culling in early lactation, a negative effect of postpartum hypocalcemia was demonstrated.