The association of circulating prepartum metabolites, minerals, cytokines and hormones with postpartum health status in dairy cattle.

The objectives were to evaluate differences in circulating prepartum metabolites, minerals, cytokines and hormones based on postpartum disease category and determine critical circulating concentrations of prepartum analytes associated with postpartum disease in 229 cattle from 11 commercial dairies in Alberta, Canada. Blood was collected at 8.8 ± 2.1 d prepartum and analyzed for a wide array of analytes. Cattle were categorized as healthy (n = 76) or as having inflammatory (INF; n = 28), metabolic (MET; n = 34) or inflammatory and metabolic (INFMET; n = 91) postpartum diseases. The prepartum circulating concentrations of Cu were lesser (0.84 vs. 0.90 µg/mL; P = 0.02) and concentrations of Mo (19.1 vs. 16.5 ng/mL; P = 0.04) and NEFA (0.27 vs. 0.18 mmol/L; P = 0.01) were greater in INFMET cattle compared with healthy cattle. The critical threshold for Cu, Mo and NEFA prepartum concentration that predicted INFMET was ≤ 0.81 µg/mL (sensitivity 45.5% and specificity 74.3%), ≥ 9.91 ng/mL (sensitivity 70.0% and specificity 52.7%) and ≥ 0.19 mmol/L (sensitivity 62.2% and specificity 79.7%), respectively. Regardless of differences in the prepartum circulating concentrations of Cu, Mo and NEFA among healthy cattle and those with postpartum disease, the use of these analytes to predict the incidence of postpartum diseases was limited.

Maternal nutrient restriction in early pregnancy increases the risk of late embryo loss despite no effects on peri-implantation interferon-stimulated genes in suckler beef cattle.

Reducing feeding costs in suckler beef herds to improve economic returns could have detrimental impacts on fertility. This study sought to determine whether maternal nutrient restriction during early pregnancy affects interferon-stimulated gene (ISG) expression in peripheral blood mononuclear cells during the peri-implantation period in two beef cattle breeds. Relationships were also examined between subnutrition and pregnancy failure defined according to ISG fold changes on Days 18 and 21 and to plasma pregnancy specific protein B (PSPB) concentrations on Day 28 post-artificial insemination (AI). Pirenaica or Parda de Montaña dams were assigned to a control (n = 23) or subnutrition (n = 30) group, receiving 100% or 65% of their estimated nutritional requirements from Day 1 to 82 post-AI, respectively. Treatment did not affect ISG expression or fertility. According to ISG fold changes (chi-square P = .023) or PSPB levels (chi-square P = .04) recorded in the subnutrition group, late embryo loss was more likely than in controls. Positive correlation was detected between Day 28 PSPB concentrations and both Day 18 MX1, MX2 and ISG15 expression, and Day 21 OAS1 expression. OAS1 and MX1 fold changes were found to be the best variables to discriminate pregnancy status. Our findings indicate that maternal nutrient restriction during the first third of pregnancy does not impair embryo signalling yet may increase the risk of pregnancy failure.

Uterine serpin (SERPINA 14) correlates negatively with cytokine production at the foetal-maternal interface but not in the corpus luteum in pregnant dairy heifers experimentally infected with Neospora caninum.

This study examines gene expression patterns in dairy heifers experimentally infected with N. caninum during on Day 110 of pregnancy with live foetuses at euthanasia, 42 days later. The study population was constituted of four non-infected controls and three infected dams. Gene expression was determined on gamma interferon (IFNγ), (Th1 pro-inflammatory cytokine), interleukin-4 (IL4) (Th2 pro-gestation cytokine) or interleukin-10 (IL10) (T regulatory cytokine) and the serine peptidase inhibitor SERPINA14 in intercaruncular, placental, uterine lymph node (UTLN) and luteal tissue samples. Intercaruncular SERPINA14 expression was negatively correlated with IFNγ expression in cotyledon samples and with IL4 expression in UTLN. No relationships were detected between cytokine gene expression at the foetal-maternal interface and SERPINA14 expression in the luteal samples. Our findings suggest that gene expression of the uterine serpin SERPINA14 correlates negatively with the expression of Th1 and Th2 cytokines at the foetal-maternal interface but not in the corpus luteum.

Influence of practitioner expertise during early pregnancy diagnosis on pregnancy loss rate: A controlled, blinded trial.

A controlled field trial was conducted to assess the potential influence of practitioner inexperience during early pregnancy diagnosis with ultrasound (PD-US) on the risk of pregnancy loss. A veterinarian with more than 10 years' experience in PD-US (Vet-A) and a veterinarian with fewer than 12 months' experience at the start of the study (Vet-B) visited the same dairy farm once a week for 33 and 26 weeks, respectively. The two veterinarians did not interact with each other at any time during the study, nor did they know that their data would later be used in this study. Using the same farm scanner, they performed PD-US at 28-34 day after breeding, together diagnosing 915 pregnancies. All cows were re-checked at 49-56 day after artificial insemination, and cows no longer pregnant were recorded as having suffered pregnancy loss. Although Vet-A and Vet-B diagnosed a similar proportion of pregnancies (58.44 ± 16% vs 56.96 ± 18%, p > .05), the rate of pregnancy loss was significantly higher among cows diagnosed by Vet-B (10.41 ± 11.2% vs 4.87 ± 9.0, p = .029). In addition, among cows diagnosed by Vet-B, the rate of pregnancy loss was significantly higher among cows diagnosed, while he had fewer than 12 months' PD-US experience (11.17 ± 12.14%) than among cows that he diagnosed later (7.14 ± 11.01%, p = .038); in fact, this latter loss rate was comparable to that among cows diagnosed by Vet-A during the same period (3.51 ± 9.83%, p = .620). These results suggest that inexperience with PD-US during the late embryonic period can increase risk of early pregnancy loss, supporting the need for proper training.

Accuracy of a cow-side test for the diagnosis of hyperketonemia and hypoglycemia in lactating dairy cows.

The objective of this study was to evaluate the use of a cow-side device (FreeStyle Precision Neo™) to diagnose ketosis and hypoglycemia based on measures of blood ß-hydroxybutyrate (BHBA) and glucose. Eleven commercial dairy farms were visited and blood samples were taken from Holstein cows between 2 and 14days in milk, yielding 441 samples for BHBA analysis and 308 samples for glucose analysis. Concentrations of BHBA and glucose were measured in two ways, 1) using the cow-side device with whole blood immediately after sampling and 2) serum samples analyzed with a standard laboratory assay (Animal Health Laboratory, University of Guelph, Canada). The accuracy of the device was determined by comparing the results to the laboratory method as well as the ability to diagnose ketosis (BHBA ≥1.2mmol/L) and hypoglycemia (glucose <2.5mmol/L). The concordance correlation coefficient (CCC), Bland-Altman plot and Kappa coefficient were calculated to evaluate agreement between the 2 methods using SAS (version 9.3). The CCC was 0.92 for BHBA and 0.56 for glucose measurements. The 95% confidence intervals of the Bland-Altman plot encompassed 97% and 95% of the mean difference between methods for BHBA and glucose measurements, respectively. The Kappa coefficients were 0.78 for BHBA and 0.23 for glucose measurements. These results indicate that the cow-side device is accurate for rapid measurement of blood BHBA and diagnosis of ketosis on farms but is not accurate for measurement of blood glucose concentrations and diagnosis of hypoglycemia.

Relationship between circulating progesterone at timed-AI and fertility in dairy cows subjected to GnRH-based protocols.

The objectives of this retrospective study were: 1) to investigate the effect of plasma progesterone (P4) concentrations at the time of timed-AI (TAI) on fertility, and 2) to examine risk factors associated with plasma P4 concentrations that impair fertility in lactating dairy cows subjected to GnRH-based protocols. Data from 872 lactating Holstein cows that had, or had not been presynchronized prior to a 7-day GnRH-based TAI protocol were examined. However, data from only those cows (n = 697; 79.9%) that ovulated after second GnRH were analyzed. Plasma P4 concentrations were determined using a solid-phase radioimmunoassay. Transrectal ultrasonography was used to determine cyclicity at first GnRH treatment, ovulation after first and second GnRH treatments, and pregnancy status at 32 and 60 d after TAI. Parity, days in milk (DIM) and BCS were also recorded. Plasma P4 concentrations at TAI ranged from 0.0 to 9.94 ng/mL (overall mean ± SEM, 0.32 ± 0.02 ng/mL) and 41 (5.9%) cows had P4 ≥ 1.0 ng/mL at TAI. The percentage of cows diagnosed pregnant at 32 and 60 d after TAI was 45.1 and 41.6%, respectively, and pregnancy loss from 32 to 60 d after TAI was 7.6%. Plasma P4 concentrations at TAI affected (P < 0.01) P/AI at 32 and 60 d, but did not affect (P > 0.1) pregnancy loss. No cows with plasma P4 concentrations >0.80 ng/mL became pregnant. However, ROC curve analysis revealed that the optimal P4 threshold at TAI for P/AI at 32 d was ≤0.50 ng/mL, with a sensitivity and specificity of 94.9 and 20.9, respectively. The percentage of cows with plasma P4 concentrations >0.50 ng/mL was 15.8% (110/697). Furthermore, a significant (P < 0.05) quadratic relationship between plasma P4 concentrations at TAI and P/AI at 32 d was observed. The maximum predicted probability of pregnancy was 0.54 at a P4 concentration of 0.26 ng/mL. Based on the odds ratios (OR), cows with P4 ≤ 6.2 ng/mL at PGF were 2.3 times less likely to have P4 > 0.50 ng/mL at TAI compared to cows with P4 > 6.2 ng/mL (OR = 0.44; 95% CI = 0.27 to 0.71; P < 0.01). Also, cyclic cows subjected to presynchronization were less likely to undergo luteal regression than non-presynchronized or acyclic cows (OR = 5.3; 95% CI = 1.77 to 16.27; P < 0.01). In summary, plasma P4 concentrations >0.50 ng/mL at TAI resulted in significantly reduced fertility. As elevated plasma P4 concentrations at TAI were more frequent in cows with lower P4 at PGF or those subjected to presynchronization, both groups are most likely to benefit from an additional PGF treatment prior to TAI.

Early postpartum administration of equine chorionic gonadotropin to dairy cows calved during the hot season: Effects on fertility after first artificial insemination.

Heat stress reduces fertility of high-producing dairy cows, and early administration of equine chorionic gonadotropin (eCG) may improve it. Here, 401 heat-stressed, high-producing dairy cows on a single commercial farm were given eCG (500 UI, n = 214) or saline (n = 187) on days 11-17 after calving, and the effects on fertility after the first artificial insemination (AI) were assessed. On post-partum day 96.34 ± 9.88, all cows were inseminated after a "double short Cosynch" synchronization protocol. Ovarian activity and uterine status were checked by ultrasound on the day of eCG administration and every 7 days thereafter for a total of 3 weeks; checks were also performed during synchronization, and 7 days after AI. On post-partum day 30, cytobrush uterine cytology was performed to check for subclinical endometritis. Pregnancy status was checked on days 30 and 60 after AI. The eCG and control groups did not differ significantly in terms of average lactations per cow (2.33 ± 1.34), days in milk at first AI (96.33 ± 9.88), average milk yield at AI (41.38 ± 7.74 L), or the particular inseminator or bull used for AI. The eCG and control groups showed increasing ovarian activity with time, with approximately 75% of cows in both groups showing a corpus luteum at the beginning of the synchronization protocol. On post-partum day 30, 17.4% of eCG cows and 22.9% of control cows showed subclinical endometritis. Cows treated with eCG showed a tendency toward lower hyperecogenic intraluminal content (16.8 vs. 21.4%, P = 0.15), but ovarian activity during the synchronization protocol was similar between eCG and control groups, with 91% of animals in both groups showing luteolysis after prostaglandin application and 88% showing ovulation after the last administration of gonadotropin-releasing hormone. Fertility was similar between the two groups at both time points after AI (30 days, 34.9 vs. 31.8%; 60 days, 30.6 vs. 28.5%; P > 0.2). These results suggest that early postpartum eCG administration does not improve fertility of heat-stressed dairy cows as long as 60 days after AI. Other strategies may be more effective at mitigating the ability of post-partum heat stress to reduce fertility of high-producing dairy cows.

Factors associated with ovarian structures and intrauterine fluid in the postpartum period in dairy cows.

The objective was to examine risk factors for the interval to resumption of ovarian cyclicity (ROC), multiple ovulations (MCL), ovarian follicular cysts (OC), and presence of intrauterine fluid (IUF) at 22 to 28 [visit (V) 1] and 36 to 42 (V2) days in milk (DIM) in dairy cows. The study was conducted retrospectively by evaluating records from 1,155 Holstein cows from 3 herds. Ovaries and uteri were examined at V1 and V2 by transrectal ultrasonography to determine ovarian structures and IUF. Based on the odds ratio, multiparous cows were more likely to have ROC at V1 by a factor of 1.79 compared with primiparous cows. The likelihood of ROC at V1 was lower in cows with higher milk production, in cows with retained fetal membranes (RFM) or cows with IUF at V1 by factors of 0.98 (for each kg of milk increased), 0.52, and 0.61, respectively. Based on the odds ratio, cows diagnosed with IUF at V2 were 2.85 times more likely to have attained ROC at V2. Multiparous cows and cows that delivered twins were 2.73 and 2.16 times, respectively, more likely to have MCL at V1, whereas cows with RFM were 0.38 times less likely to have MCL at V1. The likelihood of MCL at V2 was higher in cows with MCL and OC at V1 by factors of 2.67 and 1.91, respectively. Multiparous cows were 8.51 times more likely to have OC at V1 than primiparous cows. Higher producing cows were more likely to have OC at V2 by a factor of 1.04 compared with lower producing cows. Parity, stillbirth, RFM, and ROC at V1 were all identified as risk factors for IUF at V1. Cows with RFM and delivering twins were more likely to be diagnosed with IUF at V2 by a factor of 3.43 and 4.07, respectively. In summary, parity, twinning, RFM, metritis, IUF, and milk production were all associated with altered ovarian structures, and the presence of IUF was related to parity, twinning, RFM, and ROC in postpartum dairy cows.

Progesterone supplementation during the time of pregnancy recognition after artificial insemination improves conception rates in high-producing dairy cows.

This study examines the possible effects of progesterone (P4) supplementation during the time of pregnancy recognition, from Days 15 to 17 post-artificial insemination (AI), on reproductive performance in high-producing dairy cows. Cows in their 15th day post-AI were alternately assigned to a control, no-treatment group (C: n = 257) or treatment group (P4: n = 287) on a weekly rotational basis according to the chronologic order of their gynecologic visit. On the basis of the odds ratio, the interaction treatment × previous placenta retention had a significant effect (P = 0.02) on conception rate. Thus, cows in P4 that had not suffered a retained placenta were 1.6 times more likely to conceive 28 to 34 days post-AI than the remaining cows. In nonpregnant cows, treatment had no effect on subsequent return to estrus or AI interval and neither were any effects of treatment observed on twin pregnancy and early fetal loss rates. The results of this study demonstrate the efficacy of P4 supplementations during the time of pregnancy recognition after AI in cows without a clinical history of placenta retention.

Reproductive performance of high producing lactating cows in Coxiella-infected herds following vaccination with phase-I Coxiella burnetii vaccine during advanced pregnancy.

This study was designed to assess the safety of phase I vaccination against Coxiella burnetii in advanced pregnancy and the effect of vaccination on subsequent reproductive performance of high producing dairy cows. C. burnetii serostatus was determined in 719 dairy cows by individual serological testing. According to their serostatus, cows were randomly assigned to a control (n=359) or vaccine (n=360) group (inactivated phase I on Days 171-177 and 192-198 of gestation, Coxevac-Ceva Sante Animale). Using a χ(2)-test, vaccination had no effect on abortion before parturition, retention of placenta and stillbirth, either in seropositive as in seronegative cows. Cox's proportional hazards model revealed that cows in the vaccine group were 1.22 times more likely to conceive during the first 150 days in milk than cows in the control group. Moreover, the likelihood of pregnancy was lower in multiparous cows, cows with a retained placenta and cows undergoing first AI during the warm season compared to the remaining animals (by factors of 0.75, 0.69 and 0.69, respectively). In animals testing seronegative for C. burnetii, the likelihood of pregnancy was 1.25 times higher in vaccinated cows compared to non-vaccinated seronegative animals. No effect of vaccination on subsequent fertility was detected in seropositive animals. In conclusion, the results of this study indicate that phase I vaccination against C. burnetii during advanced pregnancy in dairy cows is safe and improves subsequent fertility of C. burnetii seronegative animals.

Coxiella burnetii shedding during the peripartum period and subsequent fertility in dairy cattle.

The objective of this study was to assess the effects of Coxiella burnetii shedding or seropositivity on post-partum recovery and subsequent fertility in high-producing dairy cows. Given the difficulty in diagnosing C. burnetii infection at the farm level, an exhaustive series of tests in 43 pregnant animals that delivered at least one live calf were conducted, including blood serology and PCR of milk or colostrum, cotyledons (only at parturition), faeces, vaginal fluid against C. burnetii on gestation Day 171-177, at parturition and on Days 1-7, 8-14, 15-21, 22-28, 29-35 and 90-97 post-partum. During scheduled herd visits, ultrasonography (US) of the genital tract and examination of vaginal fluid were performed on Days 15-21 (V1), 22-28 (V2), 29-35 (V3) and 51-57 (V4) post-partum by the same veterinarian. Logistic regression analysis revealed that the likelihood of suffering endometritis (the presence of echogenic intrauterine fluid (IUF), cervical diameter of ≥4 cm or endometrial thickness ≥0.75 cm) was lower in C. burnetii-seropositive animals (OR = 0.10), compared with C. burnetii-seronegative animals. According to Kaplan-Meier survival analysis, C. burnetii-seronegative and non-shedding cows showed a delayed return to luteal activity and conception was delayed in non-shedding animals, compared with the remaining animals. Overall, the results of our study provide useful insight into the effects of C. burnetii infection on post-partum recovery and subsequent fertility. In particular, animals not infected with Coxiella seem to be susceptible to infection and not protected against the bacterium in dairy herds. The elevated costs of determining an infection at the farm level, make monitoring of cows virtually impossible from a clinical point of view.

The influence of genital tract status in postpartum period on the subsequent reproductive performance in high producing dairy cows.

The aim of the present study was to characterize the early postpartum period in clinically healthy dairy cows by ultrasonography (US), endometrial cytology (EC), and white blood cell counts, and determine possible relationships between postpartum findings and subsequent reproductive performance. Fifty-three dairy cows were examined on Days 15 to 21 (Visit 1), 22 to 28 (Visit 2), and 29 to 35 (Visit 3) postpartum. The clinical examination included: examination of vaginal fluid, EC, transrectal palpation and ultrasonography of the genital tract (cervical diameter, endometrial thickness, presence of a corpus luteum [CL] or intrauterine fluid [IUF] and its echogenicity). Luteal activity (presence of a CL in a single visit), return to cyclicity (presence of a CL in 2 consecutive visits), and conception rate at 70 and 120 days postpartum were considered as the dependent variables in four consecutive binary logistic regression analyses. Factors affecting leukocyte counts were established by general linear model (GLM) repeated measures analysis of variance. Based on the odds ratio (OR), the likelihood of luteal activity was higher in multiparous than primiparous cows (OR = 3.75) and tended to diminish in cows showing increased endometrial thickness in Visit 1 (V1) (OR = 0.06). The likelihood of returning to cyclicity decreased for each centimeter increase in cervical diameter in V1 (OR = 0.14) and that of conception on Day 70 was lower in cows showing the presence of echogenic or anechogenic IUF in V1 (OR = 0.09 or OR = 0.13, respectively) compared with cows lacking IUF. Effects of parity and IUF were observed on neutrophil counts. Positive EC results were unrelated to the cumulative conception rate at 70 and 120 days in milk, whereas cows returning a positive EC result in V1 showed a greater likelihood of increased endometrial thickness. In conclusion, measuring cervical diameter, endometrial thickness, and detecting the echogenicity of IUF by ultrasonography from Days 15 to 21 postpartum in clinically normal cows is an appropriate tool to predict subsequent reproductive performance. Vaginal examination and transrectal palpation alone did not emerge as valuable predictors.

Reproductive performance of anoestrous high-producing dairy cows improved by adding equine chorionic gonadotrophin to a progesterone-based oestrous synchronizing protocol.

This study sought to improve the reproductive performance of anoestrous high-producing dairy cows by including equine chorionic gonadotrophin (eCG) after progesterone-releasing intravaginal device (PRID) removal. In Experiment I, 806 cows at 51-57 days post-partum were randomly assigned to a PRID (treated with PRID), PRID-500 (treated with PRID plus 500 IU of eCG) or PRID-750 (treated with PRID plus 750 IU of eCG) group. In Experiment II, 422 cows showing a long anoestrus period (animals with no oestrus signs nor luteal tissue 35 days before treatment) were randomly assigned to the PRID, PRID-500 or PRID-750 groups. The dependent variables considered in binary logistic regression analyses for both experiments were the rates of oestrus, ovulation and conception after treatment, the cumulative conception rate on Day 120 post-partum and pregnancy loss. In Experiment I, interaction between treatment and season showed a significant effect on the oestrous response. Thus, during the warm season, PRID group cows were 8.9 times more likely to express oestrus than the remaining cows. Moreover, inseminated cows with two or more corpora lutea 8-14 days after treatment were more likely to become pregnant (by a factor of 2.4) than cows with a single corpus luteum. Finally, cows without luteal structures treated with PRID were 0.4 less likely to be pregnant on Day 120 post-partum, compared with the remaining cows. In Experiment II, cows in the PRID group treated during the warm or cool season were less likely to exhibit oestrus (by a factor of 0.06 or 0.2, respectively) or ovulate (by a factor of 0.004 or 0.14, respectively) than the remaining cows. In conclusion, in anoestrous cows in both experiments, the addition of eCG to the use of an intravaginal progesterone device to induce oestrus was beneficial. The recommended dose of eCG is 500 IU.