Early-lactation diseases and fertility in 2 seasons of calving across US dairy herds

Evaluating differences in milk production, reproductive performance, and survival associated with vaginal discharge characteristics and fever in postpartum dairy cows

The objective was to assess differences in productive and reproductive performance, and survival associated with vaginal discharge characteristics and fever in postpartum dairy cows located in western and southern states of the United States. This retrospective cohort study included data from 3 experiments conducted in 9 dairies. Vaginal discharge was evaluated twice within 12 DIM and scored on a 5-point scale. The highest vaginal discharge score observed for each cow was used to allocate them into 1 of 5 possible groups (VD group) as follows: VD 1 and 2 (VD 1/2; n = 1,174) = clear mucus or lochia with or without flecks of pus; VD 3 (n = 1,802) = mucopurulent with <50% pus; VD 4 (n = 1,643) = mucopurulent with ≥50% of pus or nonfetid reddish-brownish mucus, n = 1,643; VD 5 = fetid, watery, and reddish-brownish, n = 1,800. All VD 5 cows received treatment according to each herd's protocol. Rectal temperature was assessed in a subset of VD 5 cows, and subsequently divided into fever (rectal temperature ≥39.5°C; n = 334) and no fever (n = 558) groups. A smaller proportion of cows with VD 5 (67.6%) resumed ovarian cyclicity compared with VD 1/2 (76.2%) and VD 4 (72.9%) cows; however, a similar proportion of VD 5 and VD 3 (72.6%) cows resumed ovarian cyclicity. A smaller proportion of VD 5 (85.8%) cows received at least one AI compared with VD 1/2 (91.5%), VD 3 (91.0%), or VD 4 (91.6%) cows. Although we did not detect differences in pregnancy at first AI according to VD, fewer cows with VD 5 (64.4%) were pregnant at 300 DIM than cows with VD 1/2 (76.5%), VD 3 (76.2%), or VD 4 (74.7%). Hazard of pregnancy by 300 DIM was smaller for VD 5 compared with VD 1/2, VD 3, or VD 4 cows. A greater proportion of VD 5 cows were removed from the herd within 300 DIM compared with other VD groups. Milk production was 760 kg lower within 300 DIM for VD 5 compared with VD 2, VD 3, and VD 4, whereas VD 2, VD 3, and VD 4 had similar milk production. We did not detect an association between fever at diagnosis of VD 5 and reproductive performance or milk production. A greater proportion of VD 5 cows without fever were removed from the herd by 300 DIM compared with VD 5 cows with fever. Differences in productive and reproductive performance, and removal of the herd were restricted to fetid, watery, and reddish-brownish vaginal discharge, which was independent of fever.

Customized voluntary waiting period before first insemination in primiparous dairy cows. Effect on milk production, fertility and health

Customized voluntary waiting period (VWP) before first insemination was tested in 18 commercial dairy herds in Sweden, to assess milk production, fertility and health in primiparous cows expected to be suited for extended VWP. Cow selection for extended VWP was based on 3 criteria in early lactation: 1) the 10% of cows with highest genomic persistency index, 2) cows with a difficult calving or disease during the first month of lactation, and 3) cows with higher yield during d 4-33 after calving than the herd average for primiparous cows. Cows meeting at least one of these criteria were randomly assigned to either the ExtExt treatment (extended VWP of at least 175 d, n = 174; calving interval (CInt) = 16.3 mo) or the ExtConv treatment (conventional VWP of maximum 100 d n = 173; CInt = 12.4 mo). Cows not meeting any of the criteria were assigned to the ConvConv treatment (conventional VWP, n = 183; CInt = 12.0 mo). There were no differences in milk yield per day in the CInt between treatments, although 305-d and whole-lactation (WL) milk yields were higher for ExtExt cows (10,371 and 13,803 kg) than ExtConv cows (9,812 and 10,257 kg). Milk yield at the last test milking before dry-off was lower in ExtExt compared with ExtConv cows (24.9 vs 28.3), however the results showed no difference in dry period length between the treatments. Regarding reproductive performance, the ExtExt cows had higher first service conception rate (FSCR; 60% vs. 45%) and lower number of inseminations per conception (NINS; 1.67 vs. 2.19), compared with the ExtConv cows. As expected, ConvConv cows had the lowest milk yield in 305-d, in WL, and per day in the CInt, however, FSCR and NINS did not differ between ConvConv cows and cows in the other 2 VWP treatments. Disease incidence was higher for cows in the ExtConv compared with the ConvConv treatment, but there was no difference between ExtExt and the 2 other VWP treatments. Further, no difference in proportion of cows with good udder health or culling rate was detected between any of the treatments, though due to low prevalence the study lacked power to draw major conclusions on these results. Thus prolonging VWP for suitable primiparous cows can produce benefits such as improved fertility in the form of higher FSCR and lower NINS, as well as lower dry-off yield, without compromising milk yield or prolonging dry period length.

Application of behavior data to predictive exploratory models of metritis self-cure and treatment failure in dairy cows

The objective was to evaluate the performance of exploratory models containing routinely available on-farm data, behavior data, and the combination of both to predict metritis self-cure (SC) and treatment failure (TF). Holstein cows (n = 1,061) were fitted with a collar-mounted automated-health monitoring device (AHMD) from -21 ± 3 to 60 ± 3 d relative to calving to monitor rumination time and activity. Cows were examined for diagnosis of metritis at 4 ± 1, 7 ± 1, and 9 ± 1 d in milk (DIM). Cows diagnosed with metritis (n = 132), characterized by watery, fetid, reddish/brownish vaginal discharge (VD), were randomly allocated to 1 of 2 treatments: control (CON; n = 62), no treatment at the time of metritis diagnosis (d 0); or ceftiofur (CEF; n = 70), subcutaneous injection of 6.6 mg/kg of ceftiofur crystalline-free acid on d 0 and 3 relative to diagnosis. Cure was determined 12 d after diagnosis and was considered when VD became mucoid and not fetid. Cows in CON were used to determine SC, and cows in CEF were used to determine TF. Univariable analyses were performed using farm-collected data (parity, calving season, calving-related disorders, body condition score, rectal temperature, and DIM at metritis diagnosis) and behavior data (i.e., daily averages of rumination time, activity generated by AHMD, and derived variables) to assess their association with metritis SC or TF. Variables with P-values ≤0.20 were included in the multivariable logistic regression exploratory models. To predict SC, the area under the curve (AUC) for the exploratory model containing only data routinely available on-farm was 0.75. The final exploratory model to predict SC combining routinely available on-farm data and behavior data increased the AUC to 0.87, with sensitivity (Se) of 89% and specificity (Sp) of 77%. To predict TF, the AUC for the exploratory model containing only data routinely available on-farm was 0.90. The final exploratory model combining routinely available on-farm data and behavior data increased the AUC to 0.93, with Se of 93% and Sp of 87%. Cross-validation analysis revealed that generalizability of the exploratory models was poor, which indicates that the findings are applicable to the conditions of the present exploratory study. In summary, the addition of behavior data contributed to increasing the prediction of SC and TF. Developing and validating accurate prediction models for SC could lead to a reduction in antimicrobial use, whereas accurate prediction of cows that would have TF may allow for better management decisions.

A randomized trial on the effects of heat abatement during the pre-weaning phase on growth and reproductive performance of heifers and health, reproductive and productive performances of cows

Evaluation of heat stress abatement for pre-weaned dairy calves is a rare endeavor. We aimed to assess the impacts of cooling the environment of pre-weaned calves through ceiling fans on their performance after weaning and during their first lactation. We randomly assigned female Holstein calves to one of two treatment at birth (day 0): individual frame-wire hutches in a non-cooled barn ("SH", n = 125) and individual frame-wire hutches in a barn equipped with ceiling fans ("SHF", n = 101). Calves were housed under the same barn, with treatments applied in three alternating sections. Ceiling fans (2.1 m in diameter) were positioned 4.1 m from the ground and 7.6 m apart (center-to-center). Shade cloths were used to separate the sections designated for the SH and SHF treatments. Post-weaning, heifers were commingled. We recorded body weight (BW) and average daily gain (ADG) at weaning, 5, 7, and 10 mo of age. Pregnancy to first artificial insemination (P/1AI), hazard of pregnancy, and the hazard of commencing the first lactation are reported. Body weight at first calving, P/1AI, hazard of pregnancy, and milk yield in the first lactation are reported. No differences in BW (5 mo: SH = 162.9 ± 1.6 kg vs. SHF = 162.3 ± 1.6 kg; 7 mo: SH = 200.8 ± 2.2 kg vs. SHF = 201.1 ± 2.3 kg; 10 mo: SH = 300.5 ± 2.6 kg vs. SHF = 300.0 ± 2.8 kg) and ADG (SH = 0.94 ± 0.02 kg/d, SHF = 0.94 ± 0.02 kg/d) from 5 to 10 mo of age were detected. Treatment did not affect P/1AI (SH = 53.5 %, SHF = 45.9 %) and hazard of pregnancy [SH = referent, SHF - adjusted hazard ratio (AHR) = 0.87 (95 % CI = 0.65, 1.18)], but heifers in the SHF treatment were less likely to initiate the first lactation (76.2 % vs. 86.4 %). Body weight at calving (SH = 612.4 ± 5.3 kg, SHF = 618.2 ± 5.9 kg) and milk yield (SH = 39.0 ± 0.48 kg/d, SHF = 38.3 ± 0.57 kg/d) were not different, but the SHF treatment resulted in lower P/1AI (38.4 % vs. 51.4 %) and hazard of pregnancy (AHR = 0.68, 95 % CI = 0.49, 0.93) and fewer cows starting their second lactation (57.4 % vs. 72.8 %). In our experiment, providing cooling through ceiling fans during the pre-weaning phase had a negative impact on the reproductive performance of Holstein cows during their first lactation.

Graduate Student Literature Review: Implications of transition cow health for reproductive function and targeted reproductive management

Negative associations of health disorders with reproductive performance, often measured with pregnancy risk per artificial insemination (AI) or the risk of pregnancy loss, have been demonstrated extensively. Most studies investigated common clinical diseases but did not include subclinical disorders comprehensively. They often evaluated cows subjected to hormonal synchronization protocols for timed AI, limiting the ability to understand how disease may affect spontaneous reproductive function, which is essential for targeted management programs with selective hormonal intervention. It is plausible that metabolic and inflammatory disorders have short- and long-term detrimental effects on different features of reproductive function that result in or contribute to reduced fertility. These may include: 1) reestablishment of endocrine function to promote follicular growth and first ovulation postpartum, 2) corpus luteum (CL) function, 3) estrus expression, and 4) uterine environment, fertilization, and embryonic development. In this narrative literature review, we discuss insights and knowledge gaps linking health disorders with these processes of reproductive function. A growing set of observational studies with adequate internal validity suggest that these outcomes may be affected by metabolic and inflammatory disorders that are common in the early postpartum period. A better characterization of these risk factors in multi-site studies with greater external validity is warranted to develop decision-support tools to identify subgroups of cows that are more or less likely to be successful in targeted reproductive management programs.

Randomized clinical trial of ketoprofen or ceftiofur for treatment of metritis in dairy cows

Our objectives were to compare the efficacy of ketoprofen or ceftiofur for treatment of metritis in dairy cows considering subsequent health, production, and reproduction. Cows from 2 commercial dairy farms in Ontario, Canada were examined with a Metricheck device 3 times per week from 2 to 14 d in milk (DIM). Cows with metritis (fetid vaginal discharge; n = 193) were blocked by parity and fever (rectal temperature ≥39.5°C or <39.5°C) and within each block per farm, randomly assigned to receive 3 mg/kg BW of ketoprofen (KET) or 2.2 mg/kg of ceftiofur hydrochloride (CEF), once a day for 3 d. Day of enrollment was considered study d 0. Rectal temperature and attitude were evaluated in cows with metritis on study d 0, 3, 4, 7, 10, and 13, and vaginal discharge was evaluated on study d 4, 7, 10, and 13. Body condition was scored at enrollment and 35 DIM, and serum concentration of haptoglobin was measured at d 0, 2, 4, and 7. Cows with rectal temperature ≥39.5°C or a depressed attitude on d 3 were classified as clinical failure and received treatment with ceftiofur for 3 d (KET), or 2 additional days (CEF), to a maximum of 5 d of treatment with ceftiofur. At 35 ± 3 DIM cows were examined for uterine involution by transrectal palpation, purulent vaginal discharge (PVD) by Metricheck, and endometritis by endometrial cytology. Time to onset of cyclicity was assessed by serum progesterone (P4) measurements at 28, 42, and 56 DIM. Contemporary cows from the same farms without metritis (NOMET; n = 1,043) were used for comparison. Data were analyzed with mixed linear or logistic regression or Cox's proportional hazard models, including herd as a random effect. The proportion of clinical resolution of metritis on d 3 (96% vs. 92%), of cows with fever (from d 3 to d 13 after enrollment) or fetid discharge (from d 4 to d 13 after enrollment), and the number of medical treatments (3.1 vs. 3.3) were not different between CEF and KET, respectively. Cows in KET received fewer antibiotic treatments than cows in CEF (0.3 vs. 3.1). Uterine involution, the prevalence of PVD (50% vs. 47%) and subclinical endometritis (6.6% vs. 4.3%), and the proportion of cyclic cows (82% vs. 86%) did not differ between CEF and KET. Cows in KET had greater serum haptoglobin concentration from d 2 to 7 after enrollment. The incidence of mastitis, lameness, or displaced abomasum to 60 DIM and subclinical ketosis to 21 DIM did not differ among CEF, KET, and NOMET. There were no differences in median days to first AI (CEF = 68 d; 95% CI: 65-70; KET = 69 d; 95% CI: 68-72; NOMET = 69 d; 95% CI: 68-70), and median days to pregnancy (CEF = 118 d; 95% CI: 92-145; KET = 113 d; 95% CI: 90-135; NOMET = 105 d; 95% CI: 101-109), pregnancy at first AI at 33 d after insemination (CEF = 42%; KET = 41%; NOMET = 41%), pregnancy loss after first AI (CEF = 8%; KET = 11%; NOMET = 8%), hazard of pregnancy or hazard of culling up to 300 DIM. Milk yield was not different between CEF and KET during the first 10 weeks, but lesser in KET at wk 2 and 4 and CEF at wk 2, 4, and 6 than in NOMET. In this pilot-scale study, given early detection, we did not detect differences in subsequent health, milk yield, or reproductive performance in cows with metritis initially treated for 3 d with CEF or KET. Additional, larger studies are warranted.

Use of rumination time in health risk assessment of prepartum dairy cows

The objectives of this observational cohort study were to evaluate the associations of rumination time (RT) in the last week of pregnancy with transition cow metabolism, inflammation, health, and subsequent milk production, reproduction, and culling. Pregnant nulliparous (n = 199) and parous (n = 337) cows were enrolled 21 d before the expected calving. RT and physical activity were monitored automatically by sensors from d -21 to 15 relative to calving. Blood samples were collected on d -14, -5, 4, 8, and 12 ± 1 relative to calving. Diagnoses of clinical health problems were performed by researchers from calving to 15 d in milk (DIM). In classification 1, cows were ranked based on average daily RT in the last week of pregnancy and classified into terciles as short RT (SRT), moderate RT (MRT), or long RT (LRT) for association analyses. In classification 2, RT deviation from the parity average was used in a receiver operating characteristic curve to identify the best threshold to predict postpartum clinical disease. Cows were then classified as above the threshold (AT) or below the threshold (BT). Compared with cows with LRT, cows with SRT had greater serum concentrations of NEFA (0.47 vs 0.40 ± 0.01 mmol/L), BHB (0.58 vs 0.52 ± 0.01 mmol/L), and haptoglobin (0.22 vs 0.18 ± 0.008 g/L) throughout the transition period, and reduced concentrations of glucose, cholesterol, albumin, and magnesium in a time-dependent manner. Parous cows with SRT had higher odds of postpartum clinical disease (adjusted odds ratio [AOR]: 3.7; 95% confidence interval [CI]: 2.1-6.4), lower odds of pregnancy by 210 DIM (AOR: 0.34; CI: 0.15-0.75), and lower milk production (46.9 vs 48.6 ± 0.5 kg/d) than parous cows with LRT. Deviation in prepartum RT had good predictive value for clinical disease in parous cows (area under the curve [AUC]: 0.65; CI: 0.60-0.71) but not in nulliparous (AUC: 0.51; CI: 0.42-0.59). Separation of parous cows according to the identified threshold (≤-53 min from the parity average) resulted in differences in serum concentrations of NEFA (AT = 0.31 ± 0.006, BT = 0.38 ± 0.014 mmol/L), BHB (AT = 0.49 ± 0.008, BT = 0.53 ± 0.015 mmol/L), and globulin (AT = 32.3 ± 0.3, BT = 34.8 ± 0.5 g/L) throughout the transition period, as well as in serum cholesterol, urea, magnesium, albumin, and haptoglobin in a time-dependent manner. BT parous cows had higher odds of clinical disease (AOR: 3.7; CI: 2.1-6.4), reduced hazard of pregnancy (AHR: 0.64, CI: 0.47-0.89), greater hazard of culling (AHR: 2.1, CI: 1.2-3.6), and lower milk production (46.3 ± 0.7 vs 48.5 ± 0.3 kg/d). External validation using data from 153 parous cows from a different herd and the established threshold in RT deviation (≤-53 min) resulted in similar predictive value, with the odds of postpartum disease 2.4 times greater in BT than AT (37.5 vs 20.1%). In conclusion, RT in the wk preceding calving was a reasonable predictor of postpartum health and future milk production, reproduction, and culling in parous cows but not in nulliparous cows.

Integrating uterine microbiome and metabolome to advance the understanding of the uterine environment in dairy cows with metritis

BACKGROUND

Metritis is a prevalent uterine disease that affects the welfare, fertility, and survival of dairy cows. The uterine microbiome from cows that develop metritis and those that remain healthy do not differ from calving until 2 days postpartum, after which there is a dysbiosis of the uterine microbiome characterized by a shift towards opportunistic pathogens such as Fusobacteriota and Bacteroidota. Whether these opportunistic pathogens proliferate and overtake the uterine commensals could be determined by the type of substrates present in the uterus. The objective of this study was to integrate uterine microbiome and metabolome data to advance the understanding of the uterine environment in dairy cows that develop metritis. Holstein cows (n = 104) had uterine fluid collected at calving and at the day of metritis diagnosis. Cows with metritis (n = 52) were paired with cows without metritis (n = 52) based on days after calving. First, the uterine microbiome and metabolome were evaluated individually, and then integrated using network analyses.

RESULTS

The uterine microbiome did not differ at calving but differed on the day of metritis diagnosis between cows with and without metritis. The uterine metabolome differed both at calving and on the day of metritis diagnosis between cows that did and did not develop metritis. Omics integration was performed between 6 significant bacteria genera and 153 significant metabolites on the day of metritis diagnosis. Integration was not performed at calving because there were no significant differences in the uterine microbiome. A total of 3 bacteria genera (i.e. Fusobacterium, Porphyromonas, and Bacteroides) were strongly correlated with 49 metabolites on the day of metritis diagnosis. Seven of the significant metabolites at calving were among the 49 metabolites strongly correlated with opportunistic pathogenic bacteria on the day of metritis diagnosis. The main metabolites have been associated with attenuation of biofilm formation by commensal bacteria, opportunistic pathogenic bacteria overgrowth, tissue damage and inflammation, immune evasion, and immune dysregulation.

CONCLUSIONS

The data integration presented herein helps advance the understanding of the uterine environment in dairy cows with metritis. The identified metabolites may provide a competitive advantage to the main uterine pathogens Fusobacterium, Porphyromonas and Bacteroides, and may be promising targets for future interventions aiming to reduce opportunistic pathogenic bacteria growth in the uterus.

Shifts in uterine microbiome associated with pregnancy outcomes at first insemination and clinical cure in dairy cows with metritis

Objectives were to assess differences in uterine microbiome associated with clinical cure and pregnancy outcomes in dairy cows treated for metritis. Cows with metritis (reddish-brownish, watery, and fetid vaginal discharge) were paired with cows without metritis based on parity and days postpartum. Uterine contents were collected through transcervical lavage at diagnosis, five days later following antimicrobial therapy (day 5), and at 40 days postpartum. Uterine microbiome was assessed by sequencing the V4 hypervariable region of the 16S rRNA gene. Although alpha-diversity based on Chao1, Shannon, and inverse Simpson indexes at diagnosis did not differ between cows with and without metritis, disease was associated with differences in beta-diversity. Prevalence of Porphyromonas, Bacteroides, and Veillonella was greater in cows with metritis. Streptococcus, Sphingomonas, and Ureaplasma were more prevalent in cows without metritis. Differences in beta-diversity between cows with and without metritis persisted on day 5. Uterine microbiome was not associated with clinical cure. Richness and alpha-diversity, but not beta-diversity, of uterine microbiome 40 days postpartum were associated with metritis and pregnancy. No relationship between uterine microbiome and pregnancy outcomes was observed. Results indicate that factors other than changes in intrauterine bacterial community underlie fertility loss and clinical cure in cows with metritis.

A randomized controlled trial evaluating the efficacy of systemic ceftiofur administration for metritis therapy in dairy cows and the effect of metritis cure on economically important outcomes

The main objective of this study was to evaluate the effect of ceftiofur on metritis cure, milk yield, reproductive performance, and culling up to 300 DIM. The secondary objective was to evaluate the effect of metritis cure at 5 (ECURE) and 14 (LCURE) d after diagnosis on milk production, reproduction, and culling. A total of 422 Holstein cows diagnosed with metritis from 4 herds located in TX, CA, and FL were enrolled in a randomized clinical trial. Cows diagnosed with metritis (fetid, watery, reddish/brownish uterine discharge) were blocked by herd and parity and were randomly allocated to receive systemic administration of ceftiofur (CEF) or to remain untreated (CON). In addition, 399 non-metritic cows (NMET) were included for comparison purposes. Metritis cure was evaluated at 5 and 14 d after diagnosis and was defined as the absence of metritis clinical signs. Logistic regression models were fitted to the data to assess the effect of treatment on metritis cure. Milk yield was analyzed using a mixed linear model, while logistic regression, Cox proportional hazard and Kaplan-Meier survival analysis models were fitted to culling and reproduction data. Cows treated with CEF had 1.86 (95% CI: 1.22 - 2.81) and 1.68 (95% CI: 1.02 - 2.75) greater odds of being cured than CON cows at 5 and 14 d after diagnosis, respectively. No effect of CEF was observed for milk yield; however, NMET cows had greater milk yield compared with metritic cows (CEF = 36.0, 95% CI = 33.8 - 38.1; CON = 36.1, 95% CI = 33.9 - 38.2; NMET = 36.9 kg/d, 95% CI = 34.8 - 39.4). Likewise, no effect of CEF was observed on reproductive performance and culling. Nonetheless, the likelihood of conceiving for NMET cows was 1.72 (95% CI = 1.41 - 2.12) and 1.64 (95% CI = 1.33 - 2.00) times greater than for CEF and CON cows, respectively. Ceftiofur-treated and CON cows had 2.93 (95% CI = 1.90 - 4.51) and 2.37 (95% CI = 1.51 - 3.71) greater hazard of culling compared with NMET, respectively. Regardless of treatment, no differences between ECURE and LCURE were observed on milk yield, reproduction, and culling throughout the entire lactation, but cows that cured at 5 or 14 d after diagnosis had greater milk production in the first 60 DIM compared with cows that did not cure (NCURE). Cows in ECURE and LCURE also had a 1.59 (95% CI = 1.16 - 2.16) and 1.49 (95% CI = 1.08 - 2.05) greater hazard of pregnancy and 0.43 (95% CI = 0.26-0.71) and 0.56 (95% CI = 0.34-0.92) hazard of culling compared with NCURE. Ceftiofur therapy increased metritis cure, but benefits to productivity and longevity were not observed. Also, cows that fail to cure have impaired lactation performance, but no differences regarding timing of cure were observed.

Combining reproductive outcomes predictors and automated estrus alerts recorded during the voluntary waiting period identified subgroups of cows with different reproductive performance potential

The objective was to compare differences in reproductive performance for dairy cows grouped based on the combination of data for predictors available during the prepartum period and before the end of the VWP, automated estrus alerts (AEA) during the VWP, and the combination of both factors. In a cohort study, data for AEA and potential predictors of the percentage of cows that receive insemination at detected estrus (AIE) and pregnancies per AI (P/AI) for first service, and the percentage of cows pregnant by 150 DIM (P150) were collected from -21 to 49 DIM for lactating Holstein cows (n = 886). The association between each reproductive outcome with calving season (cool, warm), calving-related events (yes, no), genomic daughter pregnancy rate (gDPR; high, medium, low), days in the close-up pen (ideal, not ideal), health disorder events (yes, no), rumination time (high or low CV prepartum and high or low increase rate postpartum), and milk yield (MY) by 49 DIM (high, medium, low) were evaluated in univariable and multivariable logistic regression models. Individual predictors (health disorders, gDPR, and MY) associated with the 3 reproductive outcomes in all models were used to group cows based on risk factors (RF; yes, n = 535 or no, n = 351) for poor reproductive performance. Specifically, cows were included in the RF group if any of the following conditions were met: the cow was in the high MY group, had low gDPR, or had at least one health disorder recorded. Cows were grouped into estrus groups during the VWP based on records of AEA (E-VWP, n = 476 or NE-VWP, n = 410). Finally, based on the combination of levels of AEA and RF cows were grouped into an estrus and no RF (E-NoRF, n = 217), no estrus and RF (NE-RF, n = 276), no estrus and no RF (NE-NoRF, n = 134), and estrus and RF (E-RF, n = 259) groups. Cows received AIE up to 31 d after the end of the VWP, and if did not receive AIE, received timed AI after an Ovsynch plus progesterone protocol. Logistic and Cox proportional hazard regression compared differences in reproductive outcomes for different grouping strategies. The NoRF (AIE:76.9%; P/AI:53.1%; P150:84.5%) and E-VWP (AIE:86.8%; P/AI:44.8%; P150:82.3%) groups had more cows AIE, P/AI, and P150 than the RF (AIE:64.5%; P/AI:34.9%; P150:72.9%) and NE-VWP (AIE:50.0%; P/AI:38.9%; P150:72.1%) groups, respectively. When both factors were combined, the largest and most consistent differences were between the E-NoRF (AIE:91.3%; P/AI:58.7%; P150:88.5%) and NE-RF groups (AIE:47.3%; P/AI:35.8%; P150:69.5%). Compared with the whole population of cows or cows grouped based on a single factor, the E-NoRF and NE-RF groups had the largest and most consistent differences with the whole cow cohort. The E-NoRF and NE-RF group also had statistically significant differences of a large magnitude when compared with the remaining cow cohort after removal of the respective group. We conclude that combining data for AEA during the VWP with other predictors of reproductive performance could be used to identify groups of cows with larger differences in expected reproductive performance than if AEA and the predictors are used alone.

Associations of inflammatory and reproductive tract disorders postpartum with pregnancy and early pregnancy loss in dairy cows

Our objective was to describe associations of postpartum health with pregnancy and pregnancy loss (P-LOSS) from d 19 to 40 after first postpartum artificial insemination (AI) in lactating Holstein cows. In 2 commercial dairy herds in Ontario, Canada, 468 Holstein cows were enrolled 21 ± 3 d before expected parturition when body condition score (BCS) and lameness were assessed. Serum total Ca, haptoglobin (Hp), and nonesterified fatty acids (NEFA) were measured at 2 and 6 ± 2 d in milk (DIM). Blood β-hydroxybutyrate (BHB) measurement and metritis detection were done at 4, 8, 11, and 15 ± 2 DIM. Cows were examined for endometritis (ENDO; ≥11.5% polymorphonuclear cells in endometrial cytology) and purulent vaginal discharge (PVD) at 35 ± 3 DIM. Lameness was assessed again at 21 and 49 ± 3 DIM and BCS at 63 ± 3 DIM. First postpartum AI occurred primarily (86%) based on detection of estrus by activity monitors, on average (± standard deviation) at 65 ± 9 DIM, and the remaining cows received timed AI at 86 ± 18 DIM. Serum progesterone (P4) was measured on d 8 and 12 after AI, and pregnancy at first AI (P/AI) was estimated by the expression of ISG15 in peripheral blood leukocytes at d 19 after AI and by pregnancy-associated glycoprotein in serum at d 29, 33, and 40 after AI. Each metabolite (Ca, Hp, NEFA, and BHB) was categorized above or below a cut-point identified with receiver operating characteristic curve analysis associated with P/AI confirmed by ultrasound at d 33 from a larger data set. Data were analyzed using multivariable mixed logistic regression models, accounting for parity, health variables, covariates (season at calving and at AI, milk yield at first Dairy Herd Improvement Association test [categorized into terciles], AI method, and DIM), and herd. The proportions of cows classified pregnant at d 19, 29, 33, and 40 after AI were 64%, 54%, 50%, and 45%, respectively. At d 19 after AI, P/AI was less likely in cows diagnosed with ENDO (52% vs. 69%) or PVD (54% vs. 67%). At d 29, P/AI was less likely in cows with Hp ≥1.54 g/L at 2 DIM (38% vs. 55%) or PVD (35% vs. 56%). Both metritis and ENDO were associated with decreased P/AI at d 40 after AI. Cows diagnosed with metritis had greater risk of P-LOSS from d 19 to 29 (43% vs. 22%) or from d 33 to 40 (37% vs. 7%) than cows without metritis. From d 29 to 33, the risk of P-LOSS was greater in cows with NEFA ≥0.73 mM at 2 DIM (13% vs. 5%) or BCS ≤2.75 at 63 DIM (14% vs. 5%). The concentration of P4 on d 8 after AI was positively associated with P/AI at d 29, 33, and 40, and negatively associated with P-LOSS from d 19 to 29. Postpartum health disorders, particularly reproductive tract disease, can have detrimental effects on early pregnancy establishment and on pregnancy maintenance from d 19 to 40 after AI.

Association of transition cow health with pregnancy per artificial insemination and pregnancy loss in Holstein cows submitted to a Double-Ovsynch protocol for first service

This observational study was conducted to evaluate the effect of transition cow health on pregnancy per artificial insemination (P/AI) and pregnancy loss (PL) in cows submitted to a Double-Ovsynch protocol (DO) for first service. Lactating Holstein cows (n = 15,041) from one commercial dairy farm in northern Germany between January 2015 to December 2021 were enrolled into a modified Double-Ovsynch protocol (GnRH, 7 d later PGF2α, 3 d later GnRH, 7 d later GnRH, 7 d later PGF2α, 24 h later PGF2α, 32 h later GnRH, and 16 to 18 h later timed artificial insemination) for first service at 72 ± 3 d in milk. Pregnancy was diagnosed at 32 and 60 d post-AI via transrectal ultrasonography. Pregnancy loss was defined as the proportion of cows diagnosed pregnant 32 d post-artificial insemination that were diagnosed nonpregnant 60 d post-artificial insemination. Health-related events (i.e., milk fever [MF], hyperketonemia [KET], retained fetal membranes [RFM], metritis, mastitis, left displaced abomasum [LDA]) were assessed by farm personnel using standard operating procedures. Multivariable logistic regression was used for testing potential associations between transition cow health event occurrence and outcome variables, including P/AI and PL. Three separate models were built for cows in first lactation, second lactation, and ≥third lactation. Overall, 20.0% (885/4,430), 34.9% (1,391/3,989), and 53.9% (3,570/6,622) of cows had at least one transition cow health event for first, second, and ≥third lactations, respectively. The most prevalent transition cow health event for first-lactation cows was metritis (10.7%; [473/4,430]), whereas second-lactation cows suffered mostly from mastitis (16.6%; [664/3,989] and KET (16.6%; [661/3,989]), and cows with ≥third lactations were mostly affected by KET (33.2%; [2,198/6,622]). We observed a negative association between inflammatory disorders (i.e., RFM, metritis, mastitis) and P/AI in all cows irrespective of parity. Metabolic disorders (i.e., MF, KET, LDA) were negatively associated with P/AI only in multiparous cows. Irrespective of parity, only uterine diseases (i.e., RFM, metritis) were significantly associated with PL. These results show that enrolling cows into a fertility protocol, such as DO, cannot overcome the carryover effects of inflammatory and metabolic disorders on P/AI and PL and highlight the importance of optimizing transition cow health as a prerequisite for achieving high fertility in a DO protocol.

Effects of targeted clinical examination based on alerts from automated health monitoring systems on herd health and performance of lactating dairy cows

Our objectives were to compare the proportion of lactating dairy cows diagnosed with health disorders (HD) and herd performance when using a health monitoring program designed to rely primarily but not exclusively on alerts from automated health monitoring (AHM) systems or a health monitoring program based primarily on systematic clinical examinations, milk yield monitoring, and visual observation of cows. In a clinical trial, at ∼30 d before expected parturition, nulliparous and parous Holstein cows, stratified by parity and days in gestation, were randomly assigned to the high-intensity clinical monitoring (HIC-M; n = 625) or automated monitoring (AUT-M; n = 624) treatment. Cows were fitted with a neck-attached rumination and physical activity monitoring tag, and individual daily milk yield data were collected from parlor milk meters. For cows in HIC-M, clinical examination was conducted daily until 10 d in milk (DIM) and then in response to milk yield reduction alerts or visual observation of clinical signs of HD over the course of 21 DIM. For cows in AUT-M, clinical examination until 21 DIM was because of health index (HI) score alerts and reduced milk yield alerts. The HI score alerts used were generated based on the manufacturer's settings for the system for the last 2-h period before cows were selected for examination. Visual observation of clinical signs of HD was used for identifying cows potentially missed by automated alerts. Binomial and quantitative data were analyzed by logistic regression and ANOVA with repeated measures, respectively. The percentage of cows diagnosed with at least 1 HD during the experimental treatments risk period tended to be greater and the incidence rate ratio of HD diagnosed was greater in the HIC-M than in the AUT-M treatment. We found no difference between treatments for cows that exited the herd up to 60 or 150 DIM, but more cows tended to exit the herd from 61 to 150 DIM in the HIC-M than in the AUT-M treatment. No differences were detectable between treatments in daily or total milk yield to 21 DIM or in weekly mean milk yield and total milk yield to 150 DIM. More cows were inseminated in estrus for first service if in the HIC-M treatment and had no HD diagnosed than if in the HIC-M treatment but with HD diagnosed, or in the AUT-M treatment and had no HD diagnosed. Cows in the AUT-M treatment with HD diagnosed did not differ from other groups. No differences between treatments were observed in pregnancies per artificial insemination or pregnancy loss for first service. Despite a reduction in the risk of diagnosis of HD, no evidence indicated that a health monitoring program that relied on AHM system alerts to select cows for clinical examination reduced herd performance compared with a more intensive program that included systematic clinical examinations of all cows for the first 10 DIM, reduced milk yield alerts, and visual observation. However, to obtain the same herd performance as with the HIC-M treatment, the AUT-M treatment required use of visual observation. In conclusion, a health monitoring program designed to rely primarily on targeted clinical examination based on alerts from automated health monitoring systems might be a feasible alternative to programs that rely more on clinical examination, provided that visual observation is used to identify cows not detected by automated alerts.

Metabolic-digestive clinical disorders of lactating dairy cows were associated with alterations of rumination, physical activity, and lying behavior monitored by an ear-attached sensor

The objective of this observational cohort study was to characterize the pattern of rumination time (RT), physical activity (PA), and lying time (LT) monitored by an automated health monitoring system, based on an ear-attached sensor, immediately before, during, and after clinical diagnosis (CD) of metabolic-digestive disorders. Sensor data were collected from 820 lactating Holstein cows monitored daily from calving up to 21 DIM for detection of health disorders (HD). Cows were grouped retrospectively in the no-clinical health disorder group (NCHD; n = 616) if no HD were diagnosed, or the metabolic-digestive group (METB-DIG; n = 58) if diagnosed with clinical ketosis or indigestion only. Cows with another clinical health disorder within -7 to +7 d of CD of displaced abomasum, clinical ketosis, or indigestion were included in the metabolic-digestive plus one group (METB-DIG+1; n = 25). Daily RT, PA, and LT, and absolute and relative changes within -7 to +7 d of CD were analyzed with linear mixed models with or without repeated measures. Rumination time and PA were smaller, and LT was greater for the METB-DIG and METB-DIG+1 group than for cows in the NCHD group for most days from -7 to +7 d of CD of HD. In general, daily RT, PA, and LT differences were larger between the METB-DIG+1 and NCHD groups than between the METB-DIG and NCHD groups. In most cases, RT and PA decreased to a nadir and LT increased to a peak immediately before or after CD of HD, with a return to levels similar to the NCHD group within 7 d of CD. Absolute values and relative changes from 5 d before CD to the day of the nadir for RT and PA or peak for LT were different for cows in the METB-DIG and METB-DIG+1 group than for the NCHD group. For PA, the METB-DIG+1 group had greater changes than the METB-DIG group. For cows affected by metabolic-digestive disorders, RT, PA, and LT on the day of CD and resolution of clinical signs were different than for cows in the NCHD group, but an increase in RT and PA or a decrease in LT was observed from the day of CD to the day of resolution of clinical signs. We conclude that dairy cows diagnosed with metabolic-digestive disorders including displaced abomasum, clinical ketosis, and indigestion presented substantial alterations in the pattern of RT, PA, and LT captured by an ear-attached sensor. Thus, automated health monitoring systems based on ear-attached sensors might be used as an aid for identifying cows with metabolic-digestive disorders. Moreover, RT, PA, and LT changes after CD might be positive indicators of recovery from metabolic-digestive disorders.

Reproduction in the era of genomics and automation

Much progress has been made in the reproductive efficiency of lactating dairy cows across the USA in the past 20years. The standardisation of evaluation of reproductive efficiency, particularly with greater focus on metrics with lesser momentum and less lag-time such as 21-day pregnancy rates (21-day PR), and the recognition that subpar reproductive efficiency negatively impacted profitability were major drivers for the changes that resulted in such progress. Once it became evident that the genetic selection of cattle for milk yield regardless of fertility traits was associated with reduced fertility, geneticists raced to identify fertility traits that could be incorporated in genetic selection programs with the hopes of improving fertility of lactating cows. Concurrently, reproductive physiologists developed ovulation synchronisation protocols such that after sequential treatment with exogenous hormones, cows could be inseminated at fixed time and without detection of oestrus and still achieve acceptable pregnancy per service. These genetic and reproductive management innovations, concurrently with improved husbandry and nutrition of periparturient cows, quickly started to move reproductive efficiency of lactating dairy cows to an upward trend that continues today. Automation has been adopted in Israel and European countries for decades, but only recently have these automated systems been more widely adopted in the USA. The selection of dairy cattle based on genetic indexes that result in positive fertility traits (e.g. daughter pregnancy rate) is positively associated with follicular growth, resumption of ovarian cycles postpartum, body condition score and insulin-like growth factor 1 concentration postpartum, and intensity of oestrus. Collectively, these positive physiological characteristics result in improved reproductive performance. Through the use of automated monitoring devices (AMD), it is possible to identify cows that resume cyclicity sooner after calving and have more intense oestrus postpartum, which are generally cows that have a more successful periparturient period. Recent experiments have demonstrated that it may be possible to adopt targeted reproductive management, utilising ovulation synchronisation protocols for cows that do not have intense oestrus postpartum and relying more heavily on insemination at AMD-detected oestrus for cows that display an intense oestrus postpartum. This strategy is likely to result in tailored hormonal therapy that will be better accepted by the public, will increase the reliance on oestrus for insemination, will improve comfort and reduce labour by reducing the number of injections cows receive in a lactation, and will allow for faster decisions about cows that should not be eligible for insemination.

Metritis and clinical mastitis events in lactating dairy cows were associated with altered patterns of rumination, physical activity, and lying behavior monitored by an ear-attached sensor

Understanding changes in parameters recorded by automated health monitoring systems based on ear-attached sensors on the days immediately before and after diagnosis of metritis and clinical mastitis can help develop dairy cow health monitoring strategies. The objective of this observational cohort study was to characterize rumination time, physical activity, and lying time monitored by an ear-attached sensor before, during, and after clinical diagnosis (CD) of metritis and clinical mastitis. Lactating Holsteins monitored daily for 21 d in milk for detection of health disorders were retrospectively included in the no clinical health disorder group (NCHD; n = 616) if no disorders were diagnosed. Cows were included in the metritis (MET; n = 69) or clinical mastitis (MAST; n = 36) group if diagnosed only with nonsevere metritis (watery, reddish, and fetid uterine discharge with or without pyrexia) or nonsevere clinical mastitis (visibly abnormal milk secretion with or without signs of udder inflammation, with no pyrexia and no systemic signs of disease), respectively. Cows diagnosed with severe metritis (signs of metritis plus systemic signs of disease) or severe clinical mastitis (signs of mastitis plus pyrexia and systemic signs of disease), and cows diagnosed with nonsevere metritis or clinical mastitis plus another disorder within -7 to +7 d of CD of metritis or clinical mastitis diagnosis, were included in the metritis plus (MET+; n = 25) or the clinical mastitis plus (MAST+; n = 15) group, respectively. Cows were fitted with an ear-attached accelerometer to measure rumination time, physical activity, and lying time. Mean daily values, mean value absolute change, and relative change for the mean daily value from 3 or 5 d before CD to the nadir for cows with metritis and clinical mastitis, respectively, were analyzed with linear mixed models with or without repeated measures. Rumination time and physical activity were lesser, and lying time was greater for the MET and MET+ groups than for the NCHD group for most days from -4 to +7 d of CD of metritis. Generally, daily rumination time, physical activity, and lying time differences were greater and more prolonged between the MET+ and NCHD than between the MET and NCHD groups. Similarly, cows in the MAST and MAST+ groups had lesser rumination time and physical activity than cows in the NCHD group for several days before diagnosis. Lying time was greater for the MAST+ than the NCHD group on d -1 and 0 relative to CD. Absolute values and relative changes from 3 d before CD to the day of the nadir for rumination time and physical activity, or peak for lying time, were different for cows in the MET and MET+ groups than for the NCHD group. Similar results were observed for the MAST and MAST+ groups compared with the NCHD group. For cows with metritis, either an increase in rumination time and physical activity or a decrease in lying time was observed from the day of CD to resolution of clinical signs, but no changes were observed for the NCHD. Cows with clinical mastitis and the NCHD group had different rumination times, physical activity, and lying times on the day of CD and resolution of clinical signs, but cows with clinical mastitis had no significant changes from the day of CD to resolution of clinical signs. We conclude that cows affected by metritis and clinical mastitis presented substantial alterations of the patterns of rumination time, physical activity, and lying time captured by an ear-attached sensor. Thus, automated health monitoring systems based on ear-attached sensors might be used as an aid for identifying cows with metritis and clinical mastitis. Moreover, behavioral parameter changes after CD might be good indicators of resolution of clinical signs of metritis but not mastitis.

Changes in Uterine Metabolome Associated with Metritis Development and Cure in Lactating Holstein Cows

The objective of this study was to identify alterations in the vaginal discharge (VD) metabolome and potential biomarkers to predict metritis development and a cure in dairy cows. This prospective cohort study was conducted on two dairies located in CA and TX. Vaginal discharge was evaluated and collected using the Metricheck® device. Cows were examined for metritis at 4, 7, and 9 days in milk (DIM). Cows with a fetid, watery, and reddish-brown uterine discharge were classified as having metritis and randomized to receive ceftiofur (n = 10) or remain untreated (n = 7). A cure was defined as the absence of a fetid, watery, reddish-brown uterine discharge at 14 d after enrollment. Vaginal discharge samples were collected from 86 cows within 6 h after parturition, at 4 and 7 DIM, at metritis diagnosis, and at 4 and 7 days after metritis diagnosis. Cows with metritis (MET; n = 17) were paired with counterparts without metritis (HTH) of a similar DIM and parity (n = 34). The uterine metabolome was evaluated using untargeted gas chromatography time-of-flight mass spectrometry (GC-TOF-MS). Metabolomic data were analyzed using the MetaboAnalyst 5.0. Data were log-transformed and auto-scaled for normalization. Univariate analyses, including the fold-change, were performed to identify the metabolites linked to metritis development and its cure and principal component analysis and partial least squares discriminant analysis were performed to explain metabolite variance between animals developing or not developing metritis and being cured or not being cured of metritis. Comparing HTH with MET cows at calving, 12 metabolites were upregulated, and one was downregulated. At four and seven DIM, 51 and 74 metabolites, respectively, were altered between MET and HTH cows. After metritis development, three and five metabolites were upregulated in cows that were cured and in cows that received treatment and were cured, respectively. In all scenarios, the metabolites lignoceric, malic, and maleic acids, ornithine, and hypotaurine, which are associated with arginine/aminoacyl-tRNA biosynthesis and taurine/purine metabolism, were upregulated in HTH cows. Metritis was associated with changes in the uterine metabolome. Cows not being cured of metritis had changes in the uterus metabolome independent of receiving ceftiofur or remaining untreated. Metabolome analysis may be an important tool to understand the vaginal discharge changes during postpartum and the dynamics of metritis development and cures and help to identify biomarkers to predict metritis being cured.

Blood metabolomics and impacted cellular mechanisms during transition into lactation in dairy cows that develop metritis

The objective of this study was to identify metabolites associated with metritis and use them for identification of cellular mechanisms affected during transition into lactation. Holstein cows (n = 104) had blood collected in the prepartum period (d -14 ± 6 relative to calving), at calving (d 0), and at the day of metritis diagnosis (d 7 ± 2 after calving). Cows with reddish or brownish, watery, and fetid discharge were diagnosed with metritis (n = 52). Cows with metritis were paired with herdmates without metritis (n = 52) based on days in milk. The metabolome of plasma samples was evaluated using untargeted gas chromatography time-of-flight mass spectrometry. Univariate analyses included t-tests and fold change analyses. Metabolites with false discovery rate adjusted P ≤ 0.10 on t-tests were used for partial least squares discriminant analysis coupled with permutational analysis using 2,000 permutations. Metabolites with false discovery rate adjusted P ≤ 0.10 on t-tests were also used for enriched pathway analyses and identification of cellular processes. Cows that developed metritis had affected cellular processes associated with lower amino acid metabolism in the prepartum period, greater lipolysis, cell death, and oxidative stress at calving and at metritis diagnosis, and greater leukocyte activation at calving, but lower immune cell activation at metritis diagnosis. In summary, cows that developed metritis had plasma metabolomic changes associated with greater lipolysis, oxidative stress, and a dysregulated immune response which may predispose cows to metritis development.

Associations between the postpartum uterine and vaginal microbiota and the subsequent development of purulent vaginal discharge vary with dairy cow breed and parity

The objective of this study was to characterize the species composition and functional potential of the vaginal and uterine microbiota at 1 wk postpartum in dairy cows diagnosed with or without purulent vaginal discharge (PVD) at 3 wk postpartum. The hypothesis was that differences in the vaginal and uterine microbiota between cows diagnosed with (PVD+) or without (PVD-) PVD were dependent on parity and breed. Cytobrush samples of the vagina and uterus were collected at 1 wk postpartum from 36 Holstein-Friesian (7 primiparous and 29 multiparous) and 29 Jersey (10 primiparous and 19 multiparous) cows. Microbial DNA was isolated from each sample and processed for shotgun metagenomic sequencing. The odds of multiparous cows being diagnosed as PVD+ was less compared with primiparous cows (OR = 0.21). Neither the α-diversity nor β-diversity of the uterine and vaginal microbiota were associated with PVD but the β-diversity was different between breeds and between parities. In the vagina of primiparous cows, differences in the microbiota of PVD- and PVD+ cows were minor, but the microbiota of multiparous PVD+ cows had greater relative abundance of Fusobacterium necrophorum, Trueperella pyogenes, Porphyromonas levii, and greater functional potential for amino acid and protein synthesis, energy metabolism, and growth compared with PVD- cows. The uterus of primiparous PVD+ cows had lesser relative abundance of Bacteroides heparinolyticus compared with PVD- cows. In the uterine microbiota, differences included greater functional potential for cellulose biosynthesis and fucose catabolism in multiparous PVD+ cows compared with PVD- cows. In the uterine microbiota of primiparous PVD+ cows, the functional potential for gram-negative cell wall synthesis and for negative regulation of tumor necrosis factor signaling was lesser compared with multiparous PVD+ cows. In the vagina of Holstein-Friesian PVD+ cows, the relative abundance of Caviibacter abscessus was greater whereas in the vagina of Jersey PVD+ cows the relative abundance of Catenibacterium mitsuokai, Finegoldia magna, Klebsiella variicola, and Streptococcus anginosus was greater compared with PVD- cows. In the uterine microbiota of Holstein-Friesian cows, the functional potential for spermidine biosynthesis was reduced compared with PVD- cows. In summary, differences in the species composition and functional potential of the vaginal and uterine microbiota between PVD- and PVD+ cows were dependent on parity and breed. The findings suggest that alternative strategies may be required to treat PVD for different parities and breeds of dairy cow.

Noninfectious Causes of Pregnancy Loss at the Late Embryonic/Early Fetal Stage in Dairy Cattle

In cattle, initial pregnancy diagnosis takes place during the late embryonic/early fetal stage of gestation. From this point onward, pregnancy loss may occur in up to one fifth of pregnancies before the initial pregnancy diagnosis is confirmed. This means the early identification of risk factors is a key part of pregnancy diagnosis and herd management. The various factors responsible for pregnancy losses are classified into infectious and noninfectious. Among the noninfectious causes, several dam-related (circumstances of the individual pregnancy or milk production) and herd-related factors causing stress have been well established. In this review, we summarize the impacts of these noninfectious factors and predict associated risks of pregnancy loss.

Association between Prepartum Alerts Generated Using a Commercial Monitoring System and Health and Production Outcomes in Multiparous Dairy Cows in Five UK Herds

Identifying cows that are at greater risk for disease prior to calving would be a valuable addition to transition management. Prior to the commercial release of software features in an automated behavioral monitoring system, designed to identify cows in the dry period at greater risk of disease postpartum, a retrospective analysis was carried out in five dairy herds to evaluate whether the software could identify prepartum cows that subsequently received health treatments postpartum and whether prepartum alerts (transition alerts) are associated with a reduction in milk production in the subsequent lactation. Herd management and production records were analyzed for cows receiving treatment in the first 21 d of lactation (days in milk, DIM) for clinical mastitis, reproductive tract disease (metritis, retained fetal membranes), metabolic disease (hypocalcemia, ketosis and displaced abomasum) and for cows exiting the herd by 60 DIM. Data was gathered for 986 cows, 382 (38.7%) of which received a transition alert and 604 (61.3%) that did not. During the first 21 DIM 312 (31.6%) cows went on to receive a disease treatment, of these 51.9% (n = 162/312) were transition alert cows and 48.1% (n = 150/312) non-transition alert cows, while 8.6% (n = 33/382) alert cows exited the herd by 60 DIM compared to 4.8% (n = 29/604) of cows that did not receive an alert. A cow receiving a transition alert (OR = 1.76, 95% confidence interval (CI) = 1.27-2.44) and increasing parity (OR = 2.03, 95% CI = 1.44-2.86) were both associated with increased risk of receiving a disease treatment in the first 21 DIM. The occurrence of a transition alert was negatively associated with both week 4 milk yield (daily average yield in fourth week of lactation) and predicted 305 d yield. Transition alerts correctly predicted 62.5% (95% CI: 59.3-65.5) of treatments with a sensitivity of 42.4% (95% CI: 37.4-45.5) and a specificity of 75.2% (95% CI: 71.5-78.6). Associations were identified between postpartum health and production outcomes and prepartum behavioral measures from an automated activity monitoring system.

ADSA Foundation Scholar Award: What makes for a good life for transition dairy cows? Current research and future directions

Dairy cows experience several challenges during the transition period, historically defined as the 3 wk before to 3 wk after calving. During this 6-wk window, cows undergo a series of social, nutritional, and physical changes that affect their quality of life. Cows are also at the highest risk of becoming ill in the days and weeks after calving compared with any other period in their adult life. Because of this, the transition cow has been a central focus of dairy cattle research for at least the last 50 yr, with much of this work targeted at identifying, treating, and preventing postpartum disease. However, understanding what makes for a good life for transition cows requires consideration of more than just their health. When considering a cow's welfare, we must also include her emotional experiences and ability to live a reasonably natural life. To gain a broader perspective on the welfare of transition cows that goes beyond their health, continued inter- and transdisciplinary approaches are needed. The aims of this narrative review are to (1) describe a framework used to study animal welfare, which includes different perspectives on what makes for a good life for animals using examples from transition cow research, (2) summarize the advancements we have made in developing our understanding of the welfare of transition dairy cows over the last several decades, (3) identify gaps in the literature and propose new and continued topics for research, and (4) suggest a path forward for researchers, including the use of methods from both the natural and social sciences to rethink existing problems, understanding barriers to adoption of evidence-based practice, and prepare for future challenges.

Risk factors for ultrasound-diagnosed endometritis and its impact on fertility in Scottish dairy cattle herds

BACKGROUND

The aim of this study was to investigate the risk factors for and the impact of ultrasound-diagnosed endometritis (UDE) on lactating dairy cows' reproductive performance.

METHODS

Data were analysed from 1123 Holstein and Holstein-Friesian cows from two Scottish dairy farms. A reproductive ultrasound examination was conducted on two occasions, at 43 ± 3 and 50 ± 3 days in milk (DIM), to screen for hyperechoic fluid in the uterus. Statistical analyses were performed using multivariable logistic regression modelling and Cox proportional hazards models.

RESULTS

The overall incidence of UDE was 8.8% (99/1123). Risk factors for UDE included calving during autumn/winter seasons, increased parity and the presence of two or more diseases in the first 50 ± 3 days postpartum. The presence of UDE was associated with a reduced odds of pregnancy after all artificial inseminations up to 150 DIM.

LIMITATIONS

The retrospective design of this study led to some inherent limitations with the quality and quantity of data collected.

CONCLUSIONS

The findings of this study indicate which risk factors should be monitored in postpartum dairy cows to limit the impact of UDE on future reproductive performance.

Review: Postpartum reproductive disease and fertility in dairy cows

This paper reviews recent data and concepts on metritis, purulent vaginal discharge (PVD), and endometritis in dairy cows and the ways in which these diseases affect reproductive performance. Metritis is characterized by fetid discharge from the uterus, with or without fever. Purulent vaginal discharge describes exudate that is >50% pus that may be attributable to uterine infection or cervicitis. Endometritis is inflammation of the uterus diagnosed by endometrial cytology with a proportion of neutrophils (typically ≥5%) that is associated with impaired fertility. Metritis and PVD are associated with uterine bacterial dysbiosis: changes in the microbiota to lesser diversity and greater abundance of pathogens, especially Gram-negative anaerobic bacteria, and Trueperella pyogenes in the case of PVD. Metritis is justifiably treated with approved antibiotics but criteria for more selective treatment without loss of performance are emerging. Purulent vaginal discharge is not synonymous with clinical endometritis, and greater precision in terminology is warranted. PVD is likely under-diagnosed and represents an opportunity for improved management in many herds. Endometritis seems in many cases to reflect persistent, dysregulated inflammation, for which the inciting cause is unclear. Postpartum uterine infection and inflammation have harmful effects on oocytes, embryo development, and the endometrium for at least three months, even if the disease is apparently resolved. Emerging concepts of the resolution and regulation of inflammation are promising for the improvement of prevention and therapy of endometritis.

Differences in uterine and serum metabolome associated with metritis in dairy cows

Objectives were to evaluate differences in the uterine and serum metabolomes associated with metritis in dairy cows. Vaginal discharge was evaluated using a Metricheck device (Simcro) at 5, 7, and 11 d in milk (DIM; herd 1) or 4, 6, 8, 10, and 12 DIM (herd 2). Cows with reddish or brownish, watery, and fetid discharge were diagnosed with metritis (n = 24). Cows with metritis were paired with herdmates without metritis (i.e., clear mucous vaginal discharge or clear lochia with ≤50% of pus) based on DIM and parity (n = 24). Day of metritis diagnosis was considered study d 0. All cows diagnosed with metritis received antimicrobial therapy. The metabolome of uterine lavage collected on d 0 and 5, and serum samples collected on d 0 were evaluated using untargeted gas chromatography time-of-flight mass spectrometry. Normalized data were subjected to multivariate canonical analysis of population using the MultBiplotR and MixOmics packages in R Studio. Univariate analyses including t-test, principal component analyses, partial least squares discriminant analyses, and pathway analyses were conducted using Metaboanalyst. The uterine metabolome differed between cows with and without metritis on d 0. Differences in the uterine metabolome associated with metritis on d 0 were related to the metabolism of butanoate, amino acids (i.e., glycine, serine, threonine, alanine, aspartate, and glutamate), glycolysis and gluconeogenesis, and the tricarboxylic acid cycle. No differences in the serum metabolome were observed between cows diagnosed with metritis and counterparts without metritis on d 0. Similarly, no differences in uterine metabolome were observed between cows with metritis and counterparts not diagnosed with metritis on d 5. These results indicate that the establishment of metritis in dairy cows is associated with local disturbances in amino acid, lipid, and carbohydrate metabolism in the uterus. The lack of differences in the uterine metabolome on d 5 indicates that processes implicated with the disease are reestablished by d 5 after diagnosis and treatment.

Individual and Combined Effects of Diseases and Cytological Endometritis on Reproductive Performance and Culling of Dairy Cows: Preliminary Results

The objective of this study was to evaluate the effect of calving-related disorders/clinical diseases (DIS) and cytological endometritis (CYTO) on the reproductive performance and culling of dairy cows. In a total of 119 multiparous Holstein cows, DIS were recorded and CYTO was diagnosed at 40 ± 2 d in milk. Onset of luteal activity was defined as the first postpartum measurement of milk progesterone >5 ng/mL. A dummy variable containing all four possible permutations between DIS and CYTO statuses was created. The pregnancy rates after first artificial insemination were 57.7, 42.9, 23.0 and 15.8% for the DIS−/CYTO−, DIS+/CYTO−, DIS−/CYTO+ and DIS+/CYTO+ groups, respectively. The hazard of pregnancy was affected by DIS−/CYTO+ and DIS+/CYTO+ health statuses (hazard ratio (HR) = 0.43 and 0.29, respectively), whereas DIS+/CYTO− and DIS−/CYTO− cows had a similar hazard to pregnancy. The hazard of onset of luteal activity was affected by DIS+/CYTO+ health status (HR = 0.45), but not by DIS+/CYTO− and DIS−/CYTO+ health statuses. Compared with DIS−/CYTO− cows, DIS−/CYTO+ and DIS+/CYTO+ cows had 4.24 and 5.57 times the odds of being culled, respectively. Culling was not affected by DIS+/CYTO− health status. In conclusion, CYTO+ status, irrespective of DIS status, decreased the pregnancy rate. When DIS+ and CYTO+ were combined, they had an additive negative effect. Our preliminary findings suggest that the far-reaching consequences of clinical diseases on fertility and culling can be mediated through the development of CYTO. Further investigations including a larger number of cows are required to confirm these results.

Association between body condition score fluctuations and pregnancy loss in Holstein cows

The objective of this study was to characterize the associations between body condition score (BCS) and BCS change (∆BCS), determined by an automated camera system during early lactation and close to artificial insemination (AI), and the subsequent pregnancy loss (PL) in Holstein cows. A secondary objective was to determine the impact of disease on PL, considering multiple time periods relative to AI. Data from 9,430 lactations in 6,884 Holstein cows in a commercial dairy operation located in Colorado, USA were included in this retrospective observational study. Cows were subject to first AI at about 80 DIM (primiparous) and 60 DIM (multiparous), following a double OvSynch protocol. Pregnancy diagnosis was performed via transrectal ultrasonography on day 32 ± 3 after AI and reconfirmed on day 80 ± 3 after AI. Cameras mounted on the sorting gate at each exit (n = 2) of the milking parlor generated BCS on a five-point scale with 0.1 increments. The BCS at calving (BCS1), 21 DIM (BCS21), 56 DIM (BCS56), AI resulting in pregnancy (BCSAI), and 90 d post AI (BCSAI90) were selected for the analyses and subsequently categorized as low (≤ lower quartile), moderate (interquartile range), and high (≥ upper quartile). Changes in BCS were calculated by periods of interest as change from calving to 21 DIM; change from calving to 56 DIM; change from 56 DIM to AI; and change from AI to 90 d post AI and assigned into categories to facilitate the analysis. Data were examined using logistic regression, considering parity category, season at calving and AI, DIM at AI, milk yield up to 60 DIM, and occurrence of disease as covariables. The logistic regression analyses indicated that the odds of PL were greater in cows in the low BCS category relative to cows in the high BCS category at 56 DIM (OR 95% CI = 1.41 [1.12-1.79]), AI (1.31 [1.05-1.65]), and 90 d post AI (1.38 [1.10-1.74]). Likewise, cows with large loss in BCS between calving and 21 DIM (1.46 [1.10-1.94]) and loss in BCS between AI and 90 d post AI (1.44 [1.15-1.81]) had greater odds of PL compared with cows with no loss of BCS within the same period. Occurrence of disease at all the time periods considered in the analysis had a consistent detrimental impact on maintenance of the pregnancy, supporting the concept that pre and postconceptional disease affects embryonic survival. Overall, low BCS, more pronounced reductions in BCS occurring closer to AI, and occurrence of disease resulted in greater PL in this Holstein population.

Combined effect of purulent vaginal discharge and anovulation on pregnancy status in a large multi-state population of Holstein cows

The objective of this observational prospective cohort study was to evaluate the combined effect of purulent vaginal discharge (PVD) and anovulation (ANOV) on the reproductive performance of a large multi-state population of Holstein cows. Data were prospectively collected from 11,729 cows in 16 herds located in 4 regions in the United States [Northeast (4 herds), Midwest (6), Southeast (1), and Southwest (5)]. Cows were enrolled at calving and monitored weekly for disease occurrence, reproductive events, and survival. Prevalence of PVD was evaluated at 28 ± 3 d in milk and defined by the presence of mucopurulent to fetid vaginal discharge. Resumption of ovarian cyclicity was determined via transrectal ultrasonography at 40 ± 3 and 54 ± 3 d postpartum. Pregnancy diagnosis was performed by ultrasonography on d 32 ± 3 after artificial insemination (AI) and reconfirmed at d 60 ± 3 of gestation. Pregnancy loss (PL) was defined as a cow diagnosed pregnant at 32 ± 3 but nonpregnant at 60 ± 3 d after AI. The association of PVD and ANOV with pregnancy traits was analyzed using 4 PVD-cyclicity categories that considered the following combinations: NPVD-CYC = absence of PVD and cycling; PVD-CYC = presence of PVD and cycling; NPVD-ANOV = absence of PVD and anovular; and PVD-ANOV = presence of PVD and anovular. Multiple logistic regression and Cox proportional regression were used for the analysis of potential associations between PVD and cyclicity categories and pregnancy at first AI (PAI1), days from calving to pregnancy, and PL at first AI. The odds (95% confidence intervals) of pregnancy increased from cows in the PVD-ANOV category (reference category) to cows in NPVD-ANOV [2.09 (1.62-2.50)], PVD-CYC [2.52 (2.02-3.14)], and NPVD-CYC [3.46 (2.84-4.23)]. Similarly, days from calving to pregnancy were less for NPVD-CYC, followed by PVD-CYC, NPVD-ANOV, and PVD-ANOV (121.4, 137.2, 137.3, and 157.4 d, respectively). On the contrary, no clear association was identified between groups and PL. The results indicate that both PVD and ANOV had a negative impact on PAI1 and days from calving to pregnancy. The results indicated a variable magnitude in the negative impact on the reproductive traits analyzed when both conditions were combined.

Effect of a targeted reproductive management program designed to prioritize insemination at detected estrus and optimize time to insemination on the reproductive performance of lactating dairy cows

The primary objective of this randomized controlled experiment was to evaluate the insemination dynamic and reproductive performance of cows managed with a targeted reproductive management (TRM) program designed to prioritize artificial insemination (AI) at detected estrus (AIE) and optimize timing of AI by grouping cows based on detection of estrus during the voluntary waiting period (VWP). Our secondary objective was to evaluate reproductive outcomes for cows with or without estrus during the VWP. Lactating Holstein cows fitted with an ear-attached sensor for detection of estrus were randomly assigned to a TRM treatment that prioritized AIE based on detection of estrus during the VWP (TP-AIE; n = 488), a non-TRM treatment that prioritized AIE (P-AIE; n = 489), or an all-timed AI (TAI) treatment with extended VWP (ALL-TAI; n = 491). In TP-AIE, cows with or without automated estrus alerts (AEA) recorded during the VWP received AIE if detected in estrus for at least 31 ± 3 or 17 ± 3 d after a 49 d VWP, respectively. Cows not AIE with or without AEA during the VWP received TAI after Ovsynch with progesterone supplementation and 2 PGF_2α treatments (P4-Ov) at 90 ± 3 or 74 ± 3 d in milk (DIM), respectively. In P-AIE, cows received AIE if detected in estrus for 24 ± 3 d after a 49 d VWP, and if not AIE received TAI at 83 ± 3 DIM after P4-Ov. In ALL-TAI, cows received TAI at 83 ± 3 DIM after a Double-Ovsynch protocol. Data were analyzed by logistic and Cox's proportional hazard regression. The proportion of cows AIE did not differ for TP-AIE (71.0%) and P-AIE (74.6%). Overall P/AI at 39 d after first service was greater for the ALL-TAI (47.6%) than for the P-AIE (40.2%) and TP-AIE (39.5%) treatments. The hazard of pregnancy up to 150 DIM was greater for cows in TP-AIE (hazard ratio (HR) = 1.2; 95% confidence interval: 1.1-1.4) and P-AIE (hazard ratio = 1.2; 95% confidence interval: 1.1-1.4) than for cows in the ALL-TAI treatment which resulted in median time to pregnancy of 89, 89, and 107 d. Conversely, the proportion of cows pregnant at 150 DIM did not differ (ALL-TAI 78.5%, P-AIE 76.3%, TP-AIE 76.0%). Except for a few outcomes for which no difference was observed, cows detected in estrus during the VWP had better performance than cows not detected in estrus. Cows with AEA during the VWP were more likely to receive AIE, had greater P/AI, and greater pregnancy rate up to 150 DIM regardless of first service management. We conclude that a TRM program designed to prioritize AIE by grouping cows based on detection of estrus during the VWP was an effective strategy to submit cows for first service resulting in similar or improved performance than a non-TRM program that prioritized AIE or an all-TAI program with extended VWP. Also, AEA recorded during the VWP might be used as a strategy for identifying subgroups of cows with different reproductive performance.

The Uterus as an Influencing Factor for Late Embryo/Early Fetal Loss—A Clinical Update

Simple Summary

Pregnancy loss following a positive pregnancy diagnosis in the absence of infectious disease of the reproductive system is a main factor limiting reproductive efficiency in high producing dairy cows. We describe here some circumstances such as the age of the dam, retained placenta and uterine size in which the uterus may be associated with pregnancy loss.

Abstract

Here we revise circumstances of non-infectious causes in which the uterus may be associated with pregnancy loss during the late embryo/early fetal period (following a positive pregnancy diagnosis in lactating dairy cows). As the uterine size increases with parity and pregnant heifers with no detrimental effects of a previous parturition, a primigravid uterus is proposed as a reference for identifying risk factors that negatively influence pregnancy in lactating cows. Cows suffering placenta retention or with a large uterus at insemination were selected as topics for this revision. Retained placenta, that occurs around parturition, has a long-lasting influence on subsequent pregnancy loss. Although retained placenta is a particularly predisposing factor for uterine infection, farm conditions along with cow factors of non-infectious cause and their interactions have been identified as main factors favoring this disorder. A large uterus (cervix and uterine horns lying outside the pelvic cavity) with no detectable abnormalities has been associated with low fertility and with a greater incidence of pregnancy loss. A large reproductive tract may well derive from an inadequate uterine involution. Therefore, peripartum management and strategies to reduce the incidence of uterine disorders should reduce their associated financial losses in the herds.

Dynamics of automatically generated body condition scores during early lactation and pregnancy at first artificial insemination of Holstein cows

The objective of this study was to characterize the association between body condition score (BCS) and BCS change (ΔBCS), determined by an automated camera system at multiple time points, and the subsequent pregnancy per first artificial insemination (P/AI1) of Holstein cows. A retrospective observational study was completed using data collected from 11,393 lactations in 7,928 Holstein cows calving between April 2019 and March 2021 in a commercial dairy operation located in Colorado. Cows were classified as primiparous or multiparous. Scores generated by BCS cameras at dry-off, calving, 21 days in milk (DIM), 56 DIM, and first artificial insemination were selected for the analyses and subsequently categorized as low (≤lower quartile), moderate (interquartile range), and high (≥upper quartile). Changes in BCS were calculated by periods of interest as change from dry-off to calving (multiparous cows); change from calving to 21 DIM; change from calving to 56 DIM; and change from calving to first artificial insemination and assigned into categories as large loss of BCS (top 25% of cows losing BCS); moderate loss (bottom 75% of cows losing BCS); no change (ΔBCS = 0); or gain of BCS (ΔBCS > 0). Data were examined in primiparous and multiparous cows separately using logistic regression and time-to-event analyses. Initial univariable models were followed by multivariable models that considered calving season, occurrence of disease, and milk yield up to 60 DIM as covariables. The logistic regression analyses indicated that in both parity groups the associations between BCS category and P/AI1 were more evident at 21 DIM, 56 DIM, and first artificial insemination, with lower odds of P/AI1 in cows in the low BCS category. Likewise, cows with large loss in BCS between calving and 21 DIM, calving and 56 DIM, and calving and first artificial insemination had lower odds of P/AI1 compared with other categories of ΔBCS within the same period of interest. Similarly, survival analyses evidenced that cows in the low BCS category required more time to get pregnant. In agreement, differences in the dynamics of the average daily BCS during the first 90 DIM were evident when cows were grouped by first AI outcome (pregnant vs. nonpregnant) and by their time to pregnancy category (<90 DIM; 91-150 DIM; or >150 DIM), with cows with reduced fertility showing lower BCS up to 90 DIM. Overall, low BCS and more pronounced reductions in BCS occurring closer to first artificial insemination resulted in lower odds of pregnancy per artificial insemination.

Effect of body condition change and health status during early lactation on performance and survival of Holstein cows

Body condition score (BCS) and disease records are commonly available in dairy operations. However, the effect of BCS changes (ΔBCS) considering specific health profiles has not been investigated extensively. The objective of this study was to assess the effects of different levels of ΔBCS on fertility, milk yield, and survival of Holstein cows diagnosed with reproductive disorders (REP; dystocia, twins, retained fetal membranes, metritis, and clinical endometritis), other health disorders (OTH; subclinical ketosis, left displaced abomasum, lameness, clinical mastitis, and respiratory disease), or with no disease events (HLT) within 40 days in milk (DIM). Data included lactation information from 11,733 cows calving between November 2012 and October 2014 in 16 herds across 4 geographical regions in the United States (Northeast, Midwest, Southwest, Southeast). Cows were evaluated for BCS at 5 ± 3 DIM (BCS5) and at 40 ± 3 DIM (BCS40) and the difference between BCS40 and BCS5 was classified as excessive loss of BCS (EL; ΔBCS ≤-0.75), moderate loss (ML; ΔBCS = -0.5 to -0.25), no change (NC; ΔBCS = 0), or gain of BCS (GN; ΔBCS ≥0.25). Multivariable logistic regression was used for assessing potential associations between the outcomes of interest and ΔBCS and health. The effect of the interaction term ΔBCS by health group was not statistically significant for any of the study outcomes. The odds of resumption of ovarian cyclicity (ROC), in GN, NC, and ML cows were 1.94 (95% CI: 1.57-2.40), 1.59 (1.28-1.97), and 1.27 (1.10-1.47) times greater than the odds of ROC in EL cows, respectively. The odds of pregnancy at 150 DIM (P150) in GN cows were 1.61 (1.20-2.17) times greater than the odds of P150 in EL cows. Cows with REP or OTH disorders had smaller odds of ROC compared with HLT cows [REP: OR = 0.65 (0.56-0.76) and OTH: OR = 0.79 (0.68-0.92)]. For pregnancy outcomes, REP cows had smaller odds of pregnancy at the first artificial insemination compared with HLT cows [0.70 (0.58-0.84)]. Similarly, REP cows had smaller odds of being diagnosed pregnant by 150 and 305 DIM compared with HLT cows [P150: 0.73 (0.59-0.87), P305: 0.58 (0.49-0.69)]. Overall, average daily milk within the first 90 DIM was greater in EL (39.5 ± 1.13 kg/d) and ML (38.9 ± 1.11 kg/d) cows than in NC (37.8 ± 1.12 kg/d) and GN (36.2 ± 1.12 kg/d) cows. On the other hand, average daily milk within the first 90 DIM was lower in REP (37.0 ± 1.11 kg/d) cows compared with OTH (38.7 ± 1.12 kg/d) and HLT cows (38.6 ± 1.11 kg/d). The magnitude of ΔBCS and the health status of early lactation cows should be considered when assessing subsequent cow performance and survival.

Effect of peripartal administration of mycobacterium cell wall fraction on health and fertility of Holstein cows under organic-certified management

The main objective of this study was to evaluate the effect of peripartal administration of a commercially available nonspecific immune stimulant (mycobacterium cell wall fraction; MCWF [Amplimune, NovaVive Inc., Napanee, ON, Canada]) on the incidence of disease during early lactation and subsequent fertility of dairy cows. A second objective was to characterize the dynamics of circulating white blood cells (WBC) and metabolic markers following treatment administration. Cows in an United States Department of Agriculture (USDA) organic-certified dairy herd were blocked by parity and, based on sequential calving dates, randomly assigned to receive two injections (5 mL s.c.) of either a placebo (saline solution) as a control (CON; n = 71) or MCWF (n = 65) at enrollment (7 d before expected calving) and within 24 h after calving. Blood samples were collected from a subsample of the study population (MCWF = 16; CON = 18) for WBC count at enrollment, at day 2 post enrollment, and at days 1, 3, 7, and 14 after calving. Serum fatty acids, beta-hydroxybutyrate, and Ca concentrations were determined at days 1 and 7 postpartum (MCWF = 21; CON = 21). Main outcome variables included incidence risk of peripartal and early lactation health disorders and pregnancy at first artificial insemination (AI), at 100, and at 150 days in milk (DIM). In addition, the average daily milk yield up to 90 DIM and death and live culling before 305 DIM were compared. Treatment effects were assessed using multivariable logistic regression, time-to-event analyses, and repeated measures analysis of variance (ANOVA). A treatment effect on the incidence risk of some of the health disorders in the study was established. Incidence risk of metritis and clinical mastitis <28 DIM was smaller in MCWF than in CON cows (36.9% vs. 50.7% and 6.3% vs. 19.7%, respectively). On the contrary, the incidence risk of respiratory disease <28 DIM was smaller in CON (0%) than in MCWF (7.7%). Reproductive performance of multiparous cows was affected by MCWF administration: pregnancy at first AI and pregnancy at 100 and 150 DIM were greater in MCWF than in CON (35.6% vs. 19.2%; 51.1% vs. 25.0%; and 64.4% vs. 40.4%, respectively). Overall, median intervals from calving to pregnancy were 90 vs. 121 d in MCWF and CON cows, respectively. No treatment effects on the dynamics of circulating WBC or in postpartum metabolic status were established. No differences for milk yield or for the proportion of cows that survived up to 305 DIM were determined, although cows in MCWF left the herd earlier than cows in CON. In conclusion, incidence risks of metritis and mastitis in early lactation were smaller in cows receiving MCWF, whereas the incidence risk of respiratory disease was smaller in CON. Fertility significantly improved in MCWF compared with CON cows. As this study was performed in an organic-certified dairy, specific health and reproductive management practices may affect the external validity of the current findings.

Effects of feeding rumen-protected methionine pre- and postpartum on reproductive outcomes of multiparous Holstein cows

Our primary objective was to evaluate the effect of feeding rumen-protected Met (RPM) in the pre- and postpartum total mixed ration (TMR) on pregnancy per artificial insemination (AI) and pregnancy loss in multiparous Holstein cows. We also evaluated multiple secondary reproductive physiological outcomes before and after AI, including uterine health, ovarian cyclicity, response to synchronization of ovulation, and markers of embryo development and size. A total of 470 multiparous Holstein cows [235 at the University of Wisconsin (UW) and 235 at Cornell University (CU)] were used for this experiment. Experimental treatment diets were applied at the pen level (2 and 4 close-up pens at CU and UW, respectively, and 12 and 6 postfresh pens at CU and UW, respectively); thus, pen was the experimental unit, and cow was the observational unit. Cows were enrolled and randomly assigned to be fed the experimental treatment diets at approximately 4 wk before parturition until 67 d of gestation [147 d in milk (DIM)] after their first service. Close-up dry cow and replicated lactation pens were randomly assigned to treatment diets: RPM, prepartum = 2.83% (UW) and 2.85% (CU), postpartum = 2.58% (UW) and 2.65% (CU); and control (CON), prepartum = 2.30% (UW) and 2.22% (CU), postpartum = 2.09% (UW) and 2.19% (CU; Met as percentage of metabolizable protein). Vaginal discharge and uterine cytology (percentage of polymorphonuclear leucocytes) were evaluated at 35 ± 3 DIM. Cows received timed AI (TAI) at 80 ± 3 DIM after synchronization of ovulation with the Double-Ovsynch protocol. Ovarian cyclicity status, response to synchronization of ovulation, and luteal function were determined by measuring circulating concentrations of progesterone at 35 and 49 ± 3 DIM, 48 and 24 h before TAI, and 8, 18, 22, 25, and 29 d after TAI. Interferon-stimulated gene expression in white blood cells were compared on 18 d after TAI (CU only) and pregnancy-specific protein B concentrations at 22, 25, 29, 32, and 67 d after TAI. Pregnancy status was determined using pregnancy-specific protein B at 25 and 29 d after TAI, and by transrectal ultrasonography at 32, 39, and 67 d after TAI. Embryo and amniotic vesicle size were determined at 32 and 39 d after TAI. Pregnancy per AI (25 d: 64.7 vs. 64.0%, 32 d: 54.3 vs. 55.1% for CON and RPM, respectively) and pregnancy loss (25 to 67 d: 22.6 vs. 19.2% for CON and RPM, respectively) for synchronized cows did not differ. The proportion of cows with purulent vaginal discharge (CON = 7.7 vs. RPM = 4.6%) and cytological endometritis (CON = 20.8 vs. RPM = 23.6%) did not differ. Cyclicity status, ovarian responses to the synchronization protocol, and synchronization rate also did not differ. In addition, fold change for interferon-stimulated genes, concentrations of pregnancy-specific protein B, and embryo size were not affected by treatments. In conclusion, feeding RPM in the pre- and postpartum TMR at the amounts used in this experiment did not affect uterine health, cyclicity, embryo development, or reproductive efficiency in dairy cows.

Association of days in close up, gestation length, and rumination around time of calving with disease and pregnancy outcomes in multiparous dairy cows

The purpose of this study was to evaluate the effect of rumination times and days spent in a close-up group before calving (DCU) on early-lactation health and reproductive outcomes in dairy cows. Data were gathered for 719 cows located in a single herd. Herd management and reproductive records were analyzed for cows receiving treatment in the first 30 d of lactation (days in milk; DIM) for clinical mastitis, reproductive tract disease, ketosis, milk fever, and displaced abomasum. Rumination times for each cow were downloaded daily from the herd's automated collar system used to generate heat and health alerts for each cow beginning at 21 d precalving until 14 d postcalving. During the first 30 DIM, 121 cows (18%) developed at least 1 disease-any combination of ketosis (40 cows, 5.9% of total), mastitis (17 cows, 2.5%), metritis (75 cows, 11%), milk fever (17 cows, 2.5%), or displaced abomasum (28 cows, 4.1%); 305 cows (45%) were pregnant again at 100 DIM, and an additional 139 cows (20%) were pregnant at 150 DIM. Principal component analysis was used to determine the relationship between gestation length and DCU and their association with the odds of developing disease in early lactation. We did not find any significant association between precalving rumination time and disease within the first 30 DIM. Higher rumination time in the week before calving was shown to be strongly linked to a shorter time to subsequent pregnancy, whereas rumination times postcalving were not associated with changes in the time to pregnancy. Principal component analysis showed that a curvilinear combination of gestation length and DCU (principal component 1) was significantly associated with changes in disease incidence in the first 30 DIM. Gestation length and time spent in close up are important management factors in reducing the incidence of disease in early lactation, and rumination times around calving may help predict future reproductive outcomes.

The economic cost of metritis in dairy herds

The objective of this study was to estimate the cost of metritis in dairy herds. Data from 11,733 dairy cows from 16 different farms located in 4 different regions of the United States were compiled for up to 305 d in milk, and 11,581 cows (2,907 with and 8,674 without metritis) were used for this study. Metritis was defined as fetid, watery, red-brownish vaginal discharge that occurs ≤21 d in milk. Continuous outcomes such as 305-d milk production, milk sales ($/cow), cow sales ($/cow), metritis treatment costs ($/cow), replacement costs ($/cow), reproduction costs ($/cow), feeding costs ($/cow), and gross profit per cow ($/cow) were analyzed using mixed effect models using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Gross profit was also compared using the Kruskal-Wallis test. Dichotomous outcomes such as pregnant and culling by 305 d in milk were analyzed using the GLIMMIX procedure of SAS. Time to pregnancy and culling were analyzed using the PHREG procedure of SAS. Models included the fixed effects of metritis, parity, and the interaction between metritis and parity, and farm as the random effect. Variables were considered significant when P ≤ 0.05. Metritis cost was calculated by subtracting the gross profit of cows with metritis from the gross profit of cows without metritis. A stochastic analysis was performed with 10,000 iterations using the observed results from each group. Milk yield and proportion of cows pregnant were lesser for cows with metritis than for cows without metritis, whereas the proportion of cows leaving the herd was greater for cows with metritis than for cows without metritis. Milk sales, feeding costs, residual cow value, and gross profit were lesser for cows with metritis than for cows without metritis. Cow sales and replacement costs were greater for cows with metritis than for cows without metritis. The mean cost of metritis from the study herds was $511 and the median was $398. The stochastic analysis showed that the mean cost of a case of metritis was $513, with 95% of the scenarios ranging from $240 to $884, and that milk price, treatment cost, replacement cost, and feed cost explained 59%, 19%, 12%, and 7%, respectively, of the total variation in cash flow differences. In conclusion, metritis caused large economic losses to dairy herds by decreasing milk production, reproduction, and survival in the herd.

The Role of Exosomal Epigenetic Modifiers in Cell Communication and Fertility of Dairy Cows

Abnormal uterine function affects conception rate and embryo development, thereby leading to poor fertility and reproduction failure. Exosomes are a nanosized subclass of extracellular vesicles (EV) that have important functions as intercellular communicators. They contain and carry transferable bioactive substances including micro RNA (miRNA) for target cells. Elements of the cargo can provide epigenetic modifications of the recipient cells and may have crucial roles in mechanisms of reproduction. The dairy industry accounts for a substantial portion of the economy of many agricultural countries. Exosomes can enhance the expression of inflammatory mediators in the endometrium, which contribute to various inflammatory diseases in transition dairy cows. This results in reduced fertility which leads to reduced milk production and increased cow maintenance costs. Thus, gaining a clear knowledge of exosomal epigenetic modifiers is critical to improving the breeding success and profitability of dairy farms. This review provides a brief overview of how exosomal miRNA contributes to inflammatory diseases and hence to poor fertility, particularly in dairy cows.