Effect of disease on reproduction in the dairy cow: a meta-analysis

Efficacy of an herbal formula Guixiong Yimu San in preventing retained placenta and improving reproductive performance in cows

Retained placenta is a common health issue, and appropriate prevention strategies are effective in postpartum health management. This study aimed to evaluate whether early intervention using GYS can prevent retained placenta and puerperal metritis, as well as enhance reproductive outcomes in cows. Each bovine in the GYS group (n = 591) received a single prophylactic dose of GYS (0.5 g/kg body weight) orally within 2 h after parturition, while those in the control group (n = 598) received no intervention. GYS treatment was associated with a decreased incidence of retained placenta (4.6% vs. 12.0%, P < 0.01, OR = 0.335), a lower puerperal metritis risk (8.8% vs. 20.1%, P < 0.01, OR = 0.369), and a reduced need for additional therapeutic antibiotics (11.2% vs. 26.1%, P < 0.01, OR = 0.342). We observed increases in the first service conception rate (59.7% vs. 49.1%, P < 0.01) and conception rate within 305 days postpartum (93.2% vs. 85.5%, P < 0.01) in the GYS group than in the control group. A significant decrease was observed in the number of services per conception (1.8 ± 1.1 vs. 2.1 ± 1.4, P < 0.01) and the calving-to-conception interval (83.6 ± 39.6 vs. 96.6 ± 52.5 days, P < 0.01) between the two groups. Additionally, GYS treatment increased milk yield on days 7, 14, and 28 postpartum without affecting milk fat, milk protein, somatic cell count (SCC), or milk urea nitrogen (MUN) on days 7 and 28 postpartum. Accordingly, the GYS was effective and safe in preventing retained placenta and to improve reproductive performance in cows. Therefore, it could be a prophylactic intervention for superior postpartum fertility in cows.

Global losses due to dairy cattle diseases: A comorbidity-adjusted economic analysis

An economic simulation was carried out over 183 milk-producing countries to estimate the global economic impacts of 12 dairy cattle diseases and health conditions: mastitis (subclinical and clinical), lameness, paratuberculosis (Johne's disease), displaced abomasum, dystocia, metritis, milk fever, ovarian cysts, retained placenta, and ketosis (subclinical and clinical). Estimates of disease impacts on milk yield, fertility, and culling were collected from the literature, standardized, meta-analyzed using a variety of methods ranging from simple averaging to random-effects models, and adjusted for comorbidities to prevent overestimation. These comorbidity-adjusted disease impacts were then combined with a set of country-level lactational incidence and/or prevalence estimates, herd characteristics, and price estimates within a series of Monte Carlo simulations that estimated and valued the economic losses due to these diseases. It was estimated that total annual global losses are USD 65 billion (B). Subclinical ketosis, clinical mastitis, and subclinical mastitis were the costliest diseases modeled, resulting in mean annual global losses of approximately USD 18B, USD 13B, and USD 9B, respectively. Estimated global annual losses due to clinical ketosis, displaced abomasum, dystocia, lameness, metritis, milk fever, ovarian cysts, paratuberculosis, and retained placenta were estimated to be USD 0.2B, 0.6B, 0.6B, 6B, 5B, 0.6B, 4B, 4B, and 3B, respectively. Without adjustment for comorbidities, when statistical associations between diseases were disregarded, mean aggregate global losses would have been overestimated by 45%. Although annual losses were greatest in India (USD 12B), the USA (USD 8B), and China (USD 5B), depending on the measure of losses used (losses as a percent of GDP, losses per capita, losses as a percent of gross milk revenue), the relative economic burden of these dairy cattle diseases across countries varied markedly.

Coxiella burnetii and Reproductive Disorders in Cattle: A Systematic Review

Coxiellosis or Q fever is an infectious zoonotic disease caused by the bacterium Coxiella burnetii. A systematic review using bibliographic research was carried out, and the focus was the relationship between C. burnetii infection and reproductive disorders in cattle [abortion/stillbirth/perinatal morality/weak calves (ASPW complex); retained foetal membranes (RFMs); metritis/endometritis; and infertility/sub-fertility]. The bibliographical search yielded 443 results from databases, but only 61 were deemed eligible. For each disorder, summary tables were prepared, and a scientific evidence score was calculated for each study based on four criteria to help assess the level of evidence for the impact of C. burnetii on the reproductive disorders assessed: type of publication (peer-reviewed or other); type of study (case-control/cohort or other); type of C. burnetii test (direct or indirect); and comparative statistical analysis (yes or no). In addition, summary tables also included information on the study population, country, authors and year of publication, key findings and an assessment of the evidence for an association. For the ASPW complex, RFMs, metritis/endometritis and infertility/sub-fertility, 43, 9, 8 and 19 studies provided data, respectively. On a scale of four, nearly 50% of all study citations had evidence scores of three or four. For ASPW, RFMs and infertility/sub-fertility, there is a significant body of evidence to support a deleterious role for Q fever. In contrast, for metritis/endometritis, the evidence is unclear. It is concluded that there is a substantial need for further research, particularly involving larger animal populations in more controlled settings. To provide more consistency, it is recommended that authors follow more precise definitions of reproductive parameters and more robust diagnostic methodologies.

Changes in bacterial community composition in the uterus of Holstein cow with endometritis before and after treatment with oxytetracycline

It is important to study the bacteria that cause endometritis to identify effective therapeutic drugs for dairy cows. In this study, 20% oxytetracycline was used to treat Holstein cows (n = 6) with severe endometritis. Additional 10 Holstein cows (5 for healthy cows, 5 for cows with mild endometritis) were also selected. At the same time, changes in bacterial communities were monitored by high-throughput sequencing. The results show that Escherichia coli, Staphylococcus aureus and other common pathogenic bacteria could be detected by traditional methods in cows both with and without endometritis. However, 16S sequencing results show that changes in the abundance of these bacteria were not significant. Endometritis is often caused by mixed infections in the uterus. Oxytetracycline did not completely remove existing bacteria. However, oxytetracycline could effectively inhibit endometritis and had a significant inhibitory effect on the genera Bacteroides, Trueperella, Peptoniphilus, Parvimonas, Porphyromonas, and Fusobacterium but had no significant inhibitory effect on the bacterial genera Marinospirillum, Erysipelothrix, and Enteractinococcus. During oxytetracycline treatment, the cell motility, endocrine system, exogenous system, glycan biosynthesis and metabolism, lipid metabolism, metabolism of terpenoids, polyketides, cofactors and vitamins, signal transduction, and transport and catabolism pathways were affected.

Propaedeutic and Therapeutic Practices Used for Retained Fetal Membranes by Rural European Veterinary Practitioners

The present study aimed to monitor the practices of European veterinarians for the diagnosis and treatment of retained fetal membranes in cattle. A questionnaire was established and distributed to veterinarians from five European countries. A total of 700 veterinarians participated in the survey. A vaginal examination, general examination and uterine palpation are carried out by 71%, 38% and 23% of veterinarians, respectively. Moreover, half of the veterinarians attempt to remove the placenta manually, 70% of them administer a combined local and general treatment if the cow has a fever (more than 39.5 °C), and 50% of them only administer IU treatment if no fever is observed. Tetracyclins, cefapirin and penicillins are the most used intrauterine (IU) antibiotics, whereas penicillin is the most used parenteral one. All other European veterinarians were less likely to use cefapirin and more likely to use oxytocin, Ca perfusion and NSAID than French and Walloon veterinarians. In conclusion, our study confirms the necessity of improving and rationalizing the diagnostic and therapeutic approach of the RFM, mainly to reduce the important problem of antibiotic resistance.

Associations among post-partum rumen fill and motility, subclinical ketosis and fertility in Holstein dairy cows

This prospective observational study aimed to investigate the association of rumen fill and motility in post-partum Holstein cows with their future reproductive performance and subclinical ketosis (SCK). The study population consisted of two independent data sets: the first (DS1) included 237 cows from 6 herds and the second one (DS2) 709 cows from 9 herds. Rumen Fill Score (RFS) was transformed into a 3 level-trait, representing very low, low and adequate dry matter intake, respectively. A binary Rumen Contraction Score (RCS) was defined as: 0: <2 contractions/2 min, impaired rumen motility and 1: ≥2 contractions/2 min, normal rumen motility. A combined binary trait based on RFS and RCS (RFCS) was also established, representing unsatisfactory and satisfactory rumen function. Three SCK traits were defined, based on 3 different thresholds, SCK_I: BHB≥1,000 mmol/L, SCK_II: BHB≥1,100 mmol/L and SCK_III: BHB≥1,200 mmol/L. Scores were assessed and blood samples collected on day 7 (DS1) or day 8 (DS2), postpartum. Kaplan-Meier survival analysis, multivariable Cox proportional hazards models and Generalized Linear Mixed Models were performed to evaluate the association of rumen and SCK traits with reproduction. Herd, parity, calving season and several postparturient diseases were also included as potential explanatory variables. Mean days from calving to pregnancy after the 1st artificial insemination (AI) and from calving to pregnancy (all AIs) were shorter for levels of rumen traits representing adequate DMI and normal rumen motility; in most cases these differences were statistically significant in both datasets. Cows with adequate DMI and normal rumen motility (only in DS2) had greater hazard (hazard ratio [HR] = 1.84 and 1.61, for RFS and RFCS, respectively) and odds (odds ratio [OR] = 2.49 and 1.98, for RFS and RFCS, respectively) for pregnancy at 1st AI. Assessment of the association of examined rumen traits with hazard and odds for pregnancy at all AIs yielded statistically significant results in both datasets. For RFS, RCS and RFCS, HRs ranged from 1.57 to 3.31 and ORs from 1.95 to 4.83. No statistically significant associations with hazard and odds for pregnancy at 1st or all AIs were detected, for any of the 3 SCK traits, in either dataset. Overall, the combined RFCS trait constantly identified more than twice the number of cows with future reproductive problems than a positive SCK blood test.

Clinical Application of Platelet Concentrates in Bovine Practice: A Systematic Review

Platelet concentrates (PCs) have become widely used in veterinary and human medicine. The PCs consist mainly of supraphysiological concentrations of platelets and, therefore, growth factors (GFs) which are stored within platelet α-granules. Among PCs, Platelet-Rich Plasma (PRP) is characterised by low-density fibrin. Research on the effect of PCs in cattle has surged in recent years; in particular, evidence has shown the positive use of PRP for treating reproductive problems, in vitro production of bovine embryos, sole ulcers and udder diseases. The aim of this report is to critically review, in accordance with the PRISMA guidelines, the available literature reporting clinical application in the bovine practice of PRP. Three bibliographic databases PubMed, Web of Science and Scopus were used for a broad search of "platelet concentrates" OR "PRP" OR "platelet-rich plasma" OR "PRF" OR "platelet-rich fibrin" AND "cows" OR "cattle". From 1196 papers, only six met the inclusion criteria. Two papers described the use of PRP in mastitis, two papers in uterine dysfunction and two papers in ovarian dysfunction. PRP offered a low-cost, easily obtained therapeutic option and showed positive results for these patients. However, given the different pathologies and definitions involved, further studies are necessary to assess its full clinical potential.

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.

Predicting dairy herd resilience on farms with conventional milking systems

This research paper addresses the problem that, thus far, there is no method available to predict herd resilience for farms that do not use automated milking systems (AMS). Recently, a methodology was developed to estimate both individual cow as well as herd resilience using daily milk yield observations at individual cow level from farms with AMS. This AMS-based method, however, is not suitable on farms that use conventional milking systems (CMS) where such individual cow milk yield observations are lacking. Therefore, this research aimed at predicting herd resilience using herd performance data that is commonly available on CMS farms. To do so, data consisting of 585 Dutch AMS farms where herd resilience estimates using the AMS-based method were available was examined. To predict herd resilience with herd performance data, only those data that are also commonly available on CMS farms were used in a 5-fold cross validation Random Forest model. These herd resilience estimates were subsequently compared with the AMS-based herd resilience estimates. Results showed that it is possible to predict with a 69.9% probability whether a herd performs with above or below average herd resilience using only variables available on CMS farms. Especially, the proportion of cows with an indication of rumen acidosis, proportion of cows with an elevated somatic cell count and the fluctuation in herd size over the years are good predictors of herd resilience. Since herd management decisions appear to affect herd resilience, a lower predicted herd resilience could be taken as a general indication that tactical or strategic management changes could be taken to improve the herd resilience.

Key performance indicators used by dairy consultants during the evaluation of reproductive performance during routine visits

Dairy farms need thorough and efficient reproduction control. Consultants specialized in reproduction use key performance indicators (KPI) to monitor the reproductive performance of farms and must be able to decipher between the approach in a first visit and routine visits. A total of 49 consultants specialized in dairy reproduction from 21 countries responded to an online survey conducted to determine the most suitable parameters during routine visits every 2 to 4 weeks. The survey was comprised of 190 questions, 178 of them rated from 0 (irrelevant) to 10 (maximum importance) points. The questions were divided into five sections: (1) consultant and farm model, (2) general data of the farm, (3) cow reproduction, (4) postpartum and metabolic disease, and (5) heifer reproduction. The median, interquartile range, minimum and maximum values, and 95% confidence interval were determined for each question. Afterward, a multivariate analysis, using between-group linkage via Ward's hierarchical clustering was conducted to generate clusters of consultants according to their response pattern. Finally, a chi-square test was conducted to assess the association between years of experience of the consultant and farm size within the clusters generated in each section of the questionnaire. The majority of the consultants considered 34 parameters to be highly important (rated 8-10) to analyze during routine visits. The consultants used several KPI (in variable quantitative range) to evaluate any of the presented sections and considered that all the five sections are critical to control. They are aware of using KPI that reflect heat detection, fertility, and farming efficiency as well as KPI that can provide information on reproductive efficiency in the near future for cows, such as postpartum and metabolic diseases. However, parameters that are relatively old and ineffective, in terms of reproductive performance control, are still highly regarded by the majority of consultants in a routine-visit scenario. Farm size and years of experience of the consultant did not influence the type or number of parameters chosen as KPI during routine visits. The parameters rated with the highest importance (rate 10) that could be considered for an easy, fast, and universal use in routine visits to assess the reproductive status were: First service CR (%), Overall pregnancy rate (%) for cows, and age at first calving (d) for heifers.

Use of intravaginal lactic acid bacteria prepartum as an approach for preventing uterine disease and its association with fertility of lactating dairy cows

The objective of this study was to evaluate the effects of the use of intravaginal probiotics prepartum on the incidence risk of metritis postpartum and conception risk after first artificial insemination (AI). A total of 606 Holstein cows were enrolled 3 wk before their expected calving date from 2 farms. Cows were randomly assigned to either receive a 2-mL dose of a combination of 3 lactic acid bacteria (probiotic treatment) washed with approximately 2 mL of a sterile saline solution, into the vaginal canal twice weekly until parturition, or no intervention (control). Metritis diagnoses were carried out on 6 and 12 d postpartum. Vaginal discharge and rectal temperature were assessed, and vaginal discharge was scored on a scale from 1 to 4, where 1 = clear and 4 = fetid, purulent discharge. Metritis was defined as cows having a vaginal discharge score of 4 with or without fever (rectal temperature ≥39.5°C) on either 6 or 12 d postpartum, or both. Cows were bred after a 60-d voluntary waiting period primarily via the detection of estrus using automated activity monitors; cows not found in estrus were enrolled onto timed AI protocols to receive first breeding before 100 DIM. Pregnancy diagnosis was carried out at d 35 ± 7 post-AI on both farms. Data were analyzed via ANOVA using linear mixed regression models and survival analysis using a Cox proportional hazard model. Total incidence risk of metritis was 23.7% and 34.4% on farm A and farm B, respectively. Overall, the incidence of metritis was not different between treatment groups (control: 41.6 ± 3.8%; probiotic: 38.6 ± 4.0%); however, an interaction by farm was detected, where the probiotic treatment reduced metritis on one farm but not on the other. Conception risk after first AI was not affected by treatment. However, we detected an interaction between parity and treatment, where multiparous cows receiving the probiotic treatment were more likely to become pregnant compared with multiparous cows within the control group (hazard ratio: 1.33; 95% confidence interval: 1.10-1.60); no effect of probiotic treatment was found on the hazard of pregnancy for primiparous cows. In addition, the probiotic treatment was associated with an increased proportion of cows being detected in estrus for the first AI postpartum. In conclusion, vaginal probiotic treatment applied during the 3 wk prepartum was associated with a decreased incidence of metritis on one farm but not the other, suggesting that farm management may be a key player influencing treatment efficacy. Overall, probiotic treatment was found to have only limited effects on fertility in the current study.

The association of subclinical hypocalcemia at 4 days in milk with reproductive outcomes in multiparous Holstein cows

Delayed or persistent episodes of subclinical hypocalcemia (SCH) have been associated with reduced milk production and feed intake and they put cows at risk for additional disease development. However, little is known about the effect of delayed or persistent SCH on reproductive outcomes. The objectives of our study were to describe the association between SCH status at 4 d in milk (DIM) with the odds of pregnancy to first service and time to pregnancy through 150 DIM. Data were collected from multiparous Holstein cows (n = 697) from 4 farms in New York State that did not receive supplemental Ca during the first 5 DIM. Cows were classified into 1 of 2 SCH groups based on blood total Ca (tCa) at 4 DIM: normocalcemic (NC; n = 515) if tCa >2.2 mmol/L at 4 DIM or SCH (n = 182) if tCa ≤2.2 mmol/L at 4 DIM. We created a multivariable logistic regression model to assess the association between SCH group and pregnancy to first service and a time-to-event analysis to evaluate the effect of SCH group on the hazard of pregnancy by 150 DIM. Cows that were SCH at 4 DIM had lower odds of pregnancy to first service [odds ratio = 0.75, 95% confidence interval (CI) = 0.61 to 0.93, incidence = 18.1%] compared with their NC counterparts (incidence = 27.4%). Similarly, SCH cows tended to have a lower hazard of pregnancy by 150 DIM (hazard ratio = 0.82, 95% CI = 0.67 to 1.01, incidence = 65.4%) than NC cows (incidence = 70.7%). Our results indicate that delayed or prolonged reductions in blood Ca in the early postpartum period, resulting in SCH at 4 DIM, were associated with reduced reproductive outcomes in multiparous cows. Our findings, in conjunction with previous reports of the negative associations of delayed or persistent SCH on health and production, suggest that reductions in blood Ca beyond the first day of lactation might be indicative of maladaptation to lactation, and the ramifications can persist beyond the immediate postpartum period.

Pegbovigrastim treatment resulted in an economic benefit in a large randomized clinical trial in grazing dairy cows

This randomized controlled trial on 4 commercial grazing dairy farms investigated whether pegbovigrastim (PEG) treatment affected partial net return as calculated from milk revenues and costs for feed, medical treatments [clinical mastitis, uterine disease, and other diseases (i.e., any medical treatment that was not intended for clinical mastitis or uterine disease)], inseminations, and culling during a full lactation in grazing dairy cows. We also explored the effect of potential interactions of PEG treatment with parity, prepartum body condition score, and prepartum nonesterified fatty acids concentration on partial net return, milk revenues, and the costs mentioned above. Holstein cows were randomly assigned to 1 of the 2 following trial arms: a first PEG dose 9.4 ± 0.3 (mean ± standard error) days before the calving date and a second dose within 24 hours after calving (PEG: primiparous = 342; multiparous = 697) compared with untreated controls (control: primiparous = 391; multiparous = 723). The effect of PEG treatment on the outcomes of interest expressed per year was tested using general linear mixed models. Results are presented as least squares means ± standard error. Overall, PEG treatment increased the partial net return, resulting in an economic benefit per cow per year of $210 ± 100. The cost of treatment of clinical mastitis was lower for PEG treated cows compared with control cows ($9 ± 3). The largest nonsignificant difference was seen for the cost of culling; additionally, PEG treatment numerically reduced the cost of culling by $145 ± 77.

Do Calving-Related Injuries of the Vestibulum Vaginae and the Vagina Affect the Reproductive Performance in Primiparous Dairy Cows?

The aim of this study was to investigate the influence of calving-related injuries of the vestibulum vaginae and the vagina on fertility measures in heifers. German Holstein heifers (n = 236) were checked for vestibulum vaginae and vaginal injuries. These were scored according to localization, depth and length. The healing process was assessed until day 42 post partum. Calving ease and the occurrence of metritis and endometritis were evaluated. In 160 heifers, the following fertility measures were calculated to assess the reproductive performance of heifers: mean interval from calving to first insemination, mean days open, mean interval from first insemination to conception, mean calving interval, mean pregnancy index, percentage of animals pregnant at 200 days p.p., and first service conception rate. On the one hand, dystocia was a risk factor for injuries of the soft birth canal, and, on the other hand, those injuries were a risk factor for metritis and endometritis. In this study, calving-related injuries of the vestibulum vaginae and the vagina had no statistically significant effect on the reproductive performance of heifers. One reason for this outcome was probably the overall good healing tendencies of those injuries in heifers.

Mastitis causes negative reproduction performance similar to genital diseases

The economic efficiency of dairy farms is directly influenced by reproductive performance. Reproductive performance is affected by postpartum health; however, it is unknown which diseases reduce reproductive performance or how often these diseases occur in tie-stall dairy farms. In this study, the 15 most frequent diseases in tie-stalls and their impact on reproduction were determined by logistic analysis. Data from reproductive and veterinary records of 814 cows (473 Holstein) calving between April 2016 and March 2018 reared in 9 tie-stall commercial dairy farms were used. The 15 most frequent diseases were identified by medical records. The odds ratio (OR) of the diseases reducing reproductive performance (days open, number of artificial insemination, and first artificial insemination days in milk) was measured by logistic regression analysis. We focused on mastitis, and factors (inflammation grade, causative bacteria) having a negative effect on reproduction were measured similarly. Of the 15 most frequent diseases, endometritis (OR: 5.45, p < 0.001), ovarian quiescence (OR: 3.95, p < 0.001), mastitis (OR: 2.49, p < 0.001), and follicular cyst (OR: 2.33, p = 0.006) significantly prolonged days open after adjusting for environmental factors (farm, parity, and calving season). Focusing on mastitis, mastitis with mild inflammation significantly prolonged days open. Mastitis and genital diseases were frequent diseases that reduced reproductive performance. Strategies to reduce the incidence of these diseases are considered effective for the economics of tie-stall dairy farms.

Postpartum intrauterine dextrose infusion: Effects on uterine health, metabolic stress, systemic inflammation, and daily milk yield in clinically healthy dairy cows

The objective of this study was to assess the effect of intrauterine dextrose infusion at 4 ± 1 d in milk (DIM) on the incidence of clinical metritis (CM), metabolic stress [i.e., body condition score (BCS), β-hydroxybutyrate (BHB) concentration, and subclinical ketosis incidence], systemic inflammation (i.e., haptoglobin concentration), and daily milk yield in clinically healthy postpartum dairy cows. Cows (n = 245) from a dairy farm located in southwest Pennsylvania were screened at 4 ± 1 DIM using a Metricheck (Simcro Tech Ltd.) device to assess vaginal discharge. In addition, overall cow health (e.g., lameness, abnormal breathing) and rectal temperature were assessed at this time. Cows (n = 134) that presented a clear dense vaginal discharge, were in clinically good health status, and had a normal rectal temperature (i.e., <39.7°C) were blocked by parity (primiparous = 64; multiparous = 70) and randomly assigned to 1 of 3 groups: (1) SAL (n = 45): 1 intrauterine infusion of isotonic saline solution (1 L/cow); (2) DEX (n = 44): 1 intrauterine infusion of a 50% dextrose solution (1 L/cow), or (3) CON (n = 45): cows remained untreated. Cows were re-screened at 7 d after enrollment (11 ± 1 DIM) using the Metricheck device to assess CM incidence (research clinical metritis incidence; RCMI). On-farm computer records (i.e., Dairycomp 305) were also used to collect clinical metritis incidence (farm clinical metritis incidence; FCMI). In addition, BCS was assessed and blood samples were collected at enrollment and at study d 7, 14, and 21. Furthermore, daily milk yield and clinical disease events for the first 60 DIM were collected from on-farm computer records. The data were analyzed using the MIXED and GLIMMIX procedures of SAS (SAS Institute Inc.) as a randomized complete block design. Although not significant, the RCMI and FCMI in DEX and SAL cows were on average 14.5 and 18.1 percentage points higher, respectively, compared with CON cows. The SAL cows had higher BHB and haptoglobin concentrations and higher incidence of subclinical ketosis compared with CON cows on study d 7. With regard to daily milk yield, there was a day by treatment interaction, where CON cows produced more milk on certain days compared with DEX and SAL cows. Based on these findings, authors conclude that intrauterine dextrose infusion in clinically healthy postpartum cows with normal vaginal discharge may be prejudicial for cow health and performance.

Is the IL1RA/IL1B Ratio a Suitable Biomarker for Subclinical Endometritis in Dairy Cows?

The adequate expression of cytokines is essential for the prevention and healing of bovine endometrial inflammation. This study investigated the intra-uterine concentration of the proinflammatory cytokine interleukin (IL)1B and its antagonist IL1RA in cows with and without subclinical endometritis (SE). Samples were taken from 37 uteri at the abattoir and 26 uteri in vivo. Uterine secretion samples were classified as showing no signs of SE (SEneg; polymorphonuclear neutrophil granulocyte (PMN) < 5%) or showing signs of SE (SEpos; PMN ≥ 5%). Concentrations and ratios for IL1B and IL1RA were measured using a commercial and a newly established AlphaLISA kit, respectively. In both groups, a higher concentration of IL1B was detected in the SEpos group compared with the SEneg group (abattoir: p = 0.027; in vivo p < 0.001). No significant differences were observed in the concentration of IL1RA (p > 0.05). In uterine secretion samples retrieved in vivo, a lower IL1RA/IL1B ratio was detected in the SEpos group compared with the SEneg group (p = 0.002). The results of this study highlight the important role of IL1B and IL1RA during endometritis and the potential of the IL1RA/IL1B ratio as a possible biomarker for SE.

In Vivo Efficacy of Echinops spinosus Decoction as a Therapeutic for Cows at Risk of Clinical Endometritis

Clinical endometritis (CE) is a multifactorial disease of dairy animals. Retained fetal membranes (RFM) and metritis are the major risk factors of CE in dairy cows. Because uterine inflammation affects the profitability of the dairy industry, antibiotics and hormonal therapies are commonly used to mitigate against the disease. However, the One-Health concept aims to reduce antibiotic use in food animals to avoid the emergence of drug resistance or residues in milk or meat. Thus, phytotherapy may represent a good alternative to antibiotics in food animals. Echinops spinosus (E. spinosus) is a natural plant known to have therapeutic, anti-inflammatory, antimicrobial, and wound-healing properties in vitro. The aim of the present study was to investigate the efficacy of E. spinosus as a preventive strategy for CE in dairy cows with other postpartum complications. Holstein−Friesian cows (n = 36) diagnosed with RFM or metritis enrolled in the study were allocated into three groups. One group received antibiotic treatment. Another group received prostaglandin injection (PG). The experimental group received E. spinosus decoction orally. As a control group, eutocic cows (n = 36), without RFM and metritis were included in the study. The efficiency of the treatment was based on the occurrence of CE and improved reproductive outcomes. At 30 ± 2 DPP, CE was diagnosed in 25%, 58.34%, and 75% in antibiotic, PG, and E. spinosus groups, respectively (p < 0.05). There were no differences between the groups at 55 ± 5 DPP (16.67%, 33.44%, and 41.67% in antibiotic, PG and E. spinosus groups, respectively, p > 0.05). The E. spinosus group had the longest open days, lowest conception rate at 150 DPP, and highest number of services per conception. Oral E. spinosus extract is ineffective as a therapeutic for cows at risk of CE. These findings may pave the way for future innovative strategies employing E. spinosus to protect cattle against endometritis.

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.

Mastitis: What It Is, Current Diagnostics, and the Potential of Metabolomics to Identify New Predictive Biomarkers

Periparturient diseases continue to be the greatest challenge to both farmers and dairy cows. They are associated with a decrease in productivity, lower profitability, and a negative impact on cows’ health as well as public health. This review article discusses the pathophysiology and diagnostic opportunities of mastitis, the most common disease of dairy cows. To better understand the disease, we dive deep into the causative agents, traditional paradigms, and the use of new technologies for diagnosis, treatment, and prevention of mastitis. This paper takes a systems biology approach by highlighting the relationship of mastitis with other diseases and introduces the use of omics sciences, specifically metabolomics and its analytical techniques. Concluding, this review is backed up by multiple studies that show how earlier identification of mastitis through predictive biomarkers can benefit the dairy industry and improve the overall animal health.

Prediction of 24-h and 6-h Periods before Calving Using a Multimodal Tail-Attached Device Equipped with a Thermistor and 3-Axis Accelerometer through Supervised Machine Learning

Simple Summary

Routine visual observation of signs of imminent calving, such as softening of ligaments around the tailhead and udder distension, is time-consuming, and the resulting calving predictions are relatively unreliable. To address this issue, we used a multimodal tail-attached device (tail sensor) and developed calving prediction models through supervised machine learning. The tail sensor is equipped with a thermistor and 3-axis accelerometer, and can monitor tail skin temperature, activity intensity, lying time, posture changes (standing to lying or vice versa), and tail raising behavior. Using the sensor data with a non-sensor-based data (days to the expected calving date), we developed calving prediction models for 24-h and 6-h periods before calving and evaluated their predictive ability under two distinct housing conditions, tethering (tie-stall) and untethering (free-stall and individual pen). Our results demonstrated that calving prediction models based on tail sensor data with supervised machine learning have the potential to achieve effective calving prediction, irrespective of the cattle housing conditions.

Abstract

In this study, we developed calving prediction models for 24-h and 6-h periods before calving using data on physiological (tail skin temperature) and behavioral (activity intensity, lying time, posture change, and tail raising) parameters obtained using a multimodal tail-attached device (tail sensor). The efficiencies of the models were validated under tethering (tie-stall) and untethering (free-stall and individual pen) conditions. Data were collected from 33 and 30 pregnant cattle under tethering and untethering conditions, respectively, from approximately 15 days before the expected calving date. Based on pre-calving changes, 40 features (8 physiological and 32 behavioral) were extracted from the sensor data, and one non-sensor-based feature (days to the expected calving date) was added to develop models using a support vector machine. Cross-validation showed that calving within the next 24 h under tethering and untethering conditions was predicted with a sensitivity of 97% and 93% and precision of 80% and 76%, respectively, while calving within the next 6 h was predicted with a sensitivity of 91% and 90% and precision of 88% and 90%, respectively. Calving prediction models based on the tail sensor data with supervised machine learning have the potential to achieve effective calving prediction, irrespective of the cattle housing conditions.

Key Performance Indicators Used by Dairy Consultants During the Evaluation of Reproductive Performance in a First Visit

Reproduction plays a fundamental role in the profitability of dairy farms. Consultants use key performance indicators (KPI) to monitor the reproductive performance of the farms. They must decipher between the most suitable ones to face two different scenarios that may need the analysis of different parameters: (1) approach in a first visit, and (2) routine visits. Forty-nine consultants specialized in dairy reproduction from 21 countries responded to an online survey conducted to determine the most suitable parameters in a first visit approach. The survey was comprised of 190 questions, 178 of them rated from 0 (irrelevant) to 10 (maximum importance) points. The questions were divided into 5 sections: (1) consultant and farm model, (2) general data of the farm, (3) cow reproduction, (4) postpartum and metabolic disease, and (5) heifer reproduction. The median, interquartile range, minimum and maximum values, and 95% confidence interval (CI) were determined for each question. Afterward, a multivariate analysis, using between-group linkage via Ward's hierarchical clustering was conducted to generate clusters of consultants according to their response pattern. Lastly, a Chi-square test was conducted to assess the association between the years of experience of the consultant and farm size within the clusters generated in each section of the questionnaire. Most of the consultants considered 27 parameters to be highly important to analyze during the first visit. Consultants use several KPIs (in variable quantitative range) to evaluate any of the presented sections. Moreover, consultants preferred parameters focused on heat detection, fertility, and pregnancy achievement regarding the production cycle of a dairy cow. Consultants also showed high interest in obtaining a general overview of milk production, farming efficiency, and the heifer rearing process; but the farm size and the years of experience of the consultant influenced the type and number of parameters chosen as KPI. The parameters rated with the highest importance (rate 10) that could be considered for an easy, fast, and universal first visit to assess the reproductive status were: first service conception rate, overall pregnancy rate, and 21d pregnancy rate for cows, and age at first calving for heifers.

Success rate of artificial insemination, reproductive performance and economic impact of failure of first service insemination: a retrospective study

Background

A retrospective cohort study using a 10 year artificial insemination (AI) and cow reproductive performance data was conducted to study the success rate of AI; associations between effectiveness of AI and breed, AI season and, number of service per conception, and economic impact of failure of FSC in Dessie town, Dessie zuria and Kutaber districts. A total of 3480 dairy cows’ AI and reproductive performance records which were performed between 2003 and 2013 in the three selected districts of South Wollo were used. The economic losses and costs for cows that failed to conceive at their first AI associated with the larger number of days open were estimated.

Result

The prevalence of conception has a statistically significant difference between breeds of cows (P = 0.019). The non-return rate for first service was 58.54%. The median days to first service (DFS), inter-service interval (ISI) and gestation length (GL) were 126, 30 and 278 days respectively. Whereas, the mean + SD days open, calving interval (CI), number of inseminations (NOI) and number of services per conception (NSPC) were 147.2 ± 60.26, 424.5 ± 60.55, 1.14 ± 0.38 and 1.15 ± 0.39 respectively. Based on AI season there was a significant difference in conception between winter and spring (P = 0.021). There is a 45.04 days extension in the mean calving to conception interval in cows that did not conceive at their first AI but conceived by 2nd and 3rd AI than in cows that did conceive at their first AI. A total of 21,665.3 ETB extra costs was spent on reproductive treatment and other management for cows that failed to conceive at their first AI but conceived by second and third service. In cows that did not conceive totally the owner losses on average 473.7 ETB per cow per day extra costs until the cows will be culled.

Conclusion

Therefore to increase the conception rate and decrease the economic loss the owners of the dairy cows should supervise the cows regularly and should be trained on how to identify cows on estrous, the AI technicians should be trained to conduct the AI service accurately.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03325-1.

Estimating the burden of multiple endemic diseases and health conditions using Bayes’ Theorem: A conditional probability model applied to UK dairy cattle

The Global Burden of Animal Diseases (GBADs) is an international collaboration aiming, in part, to measure and improve societal outcomes from livestock. One GBADs objective is to estimate the economic impact of endemic diseases in livestock. However, if individual disease impact estimates are linearly aggregated without consideration for associations among diseases, there is the potential to double count impacts, overestimating the total burden. Accordingly, the authors propose a method to adjust an array of individual disease impact estimates so that they may be aggregated without overlap. Using Bayes’ Theorem, conditional probabilities were derived from inter-disease odds ratios in the literature. These conditional probabilities were used to calculate the excess probability of disease among animals with associated conditions, or the probability of disease overlap given the odds of coinfection, which were then used to adjust disease impact estimates so that they may be aggregated. The aggregate impacts, or the yield, fertility, and mortality gaps due to disease, were then attributed and valued, generating disease-specific losses. The approach was illustrated using an example dairy cattle system with input values and supporting parameters from the UK, with 13 diseases and health conditions endemic to UK dairy cattle: cystic ovary, disease caused by gastrointestinal nematodes, displaced abomasum, dystocia, fasciolosis, lameness, mastitis, metritis, milk fever, neosporosis, paratuberculosis, retained placenta, and subclinical ketosis. The diseases and conditions modelled resulted in total adjusted losses of £ 404/cow/year, equivalent to herd-level losses of £ 60,000/year. Unadjusted aggregation methods suggested losses 14–61% greater. Although lameness was identified as the costliest condition (28% of total losses), variations in the prevalence of fasciolosis, neosporosis, and paratuberculosis (only a combined 22% of total losses) were nearly as impactful individually as variations in the prevalence of lameness. The results suggest that from a disease control policy perspective, the costliness of a disease may not always be the best indicator of the investment its control warrants; the costliness rankings varied across approaches and total losses were found to be surprisingly sensitive to variations in the prevalence of relatively uncostly diseases. This approach allows for disease impact estimates to be aggregated without double counting. It can be applied to any livestock system in any region with any set of endemic diseases, and can be updated as new prevalence, impact, and disease association data become available. This approach also provides researchers and policymakers an alternative tool to rank prevention priorities.

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Three approaches to impact aggregation for multiple endemic diseases explored.

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Flexible method proposed to avoid double counting impacts within a livestock system.

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Illustrated using 13 endemic diseases and health conditions in UK dairy cattle.

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Provides an alternative perspective on ranking disease prevention priorities.

Effect of retained placenta and clinical mastitis on reproduction parameters, immune response, and steroidogenic receptors gene expression in postpartum crossbred dairy cows

The purpose of this study was to evaluate the effect of retained placenta (RP) and clinical mastitis (CM) on the reproductive efficiency of crossbred dairy cows during the postpartum period and the effect in some innate immune system indicators. For this, two experiments were carried out. In the first, a total of 232 cows were evaluated and divided as: healthy control (n = 184), RP (n = 22), and CM (n = 26) groups. The RP and CM was evaluated until 30 days postpartum (DPP) and reproductive rates were measured. In experiment 2, cows were divided in control (n = 10), RP (n = 10), and CM (n = 30) groups. Between 40 and 50 DPP, clinical, gynecological examination and endometrial cytobrush were performed to evaluate subclinical endometritis (SE) and gene expression of interleukins 1β (IL-1β) and 6 (IL-6), chemokine ligand 5 (CCL5), estrogen α (ESR1), and progesterone (PGR) receptors by qRT-PCR analysis. In experiment 1, the conception rate at 1st artificial insemination (AI) was lower in RP and CM groups and pregnancy rate at 150 days decreased in CM group. Calving-to-1st AI interval and days open were shorter in healthy cows. In experiment 2, the occurrence of SE was 26.7% and higher in RP and CM groups. The expression of IL-1β increased in RP and CM groups, while IL-6 was less expressed in RP group. The CCL5, ESR1, and PGR were similar between groups. In conclusion, cows with RP and CM had their reproductive efficiency negatively affected and had they initial pro-inflammatory response improved by the increase of IL-β.

Alteration in Activity Patterns of Cows as a Result of Pain Due to Health Conditions

Simple Summary

There are several conditions and diseases considered painful to cattle. One reason for the inconsistency in pain recognition and thus pain relief in cattle is the inadequate ability to identify and assess pain. In fact, both increased and/or reduced daily lying time can be indicative of pain in cattle. This review helps to properly interpret pain in cows through behavioural activity patterns and explores whether pain relief is capable to restore their normal activity.

Abstract

The main conditions and diseases considered painful in dairy cows are mastitis, lameness, calving (including dystocia and caesarean section) and metritis. The cattle literature reports that deviation from normal daily activity patterns (both increased and/or reduced daily lying time) can be indicative of painful conditions and diseases in cows. This narrative review discusses on how pain due to several health conditions in dairy cows modifies its activity pattern and explores if non-steroidal anti-inflammatory drugs (NSAIDs) are capable of restoring it. Divergent outcomes may differ depending upon the painful cause, the severity and the moment, and consequently its interpretation should be properly explained. For instance, cows with clinical mastitis reduced their time lying and increased the number of lying bouts and stepping due to pain caused by the swollen udder when cows are lying. However, lame cows show longer lying times, with a lower number of lying bouts and longer and more variable lying bouts duration, as compared to non-lame cows. When the relationship between painful disorders and daily activity patterns is studied, factors such as parity, bedding type and severity of disease are important factors to take into consideration. The potential benefits of the NSAIDs treatment in painful health disorders depend upon the type of drug administered, its dosage and administration mode, and the time of administration relative to the painful health disorder. This narrative review can be used as a tool to properly interpret and grade pain in cows through behavioural activity patterns and proposes directions for future investigations.

Major Nutritional Metabolic Alterations Influencing the Reproductive System of Postpartum Dairy Cows

Early successful conception of postpartum dairy cows is crucial in determining the optimum reproductive efficiency and profitability in modern dairy farming. Due to the inherent high production potential of modern dairy cows, the extra stress burden of peri-parturient events, and associated endocrine and metabolic changes causes negative energy balance (NEBAL) in postpartum cows. The occurrence of NEBAL is associated with excessive fat mobilization in the form of non-esterified fatty acids (NEFAs). The phenomenon of NEFA mobilization furthers with occurrence of ketosis and fatty liver in postpartum dairy cows. High NEFAs and ketones are negatively associated with health and reproductive processes. An additional burden of hypocalcemia, ruminal acidosis, and high protein metabolism in postpartum cows presents further consequences for health and reproductive performance of postpartum dairy cows. This review intends to comprehend these major nutritional metabolic alterations, their mechanisms of influence on the reproduction process, and relevant mitigation strategies.

Identification of Bull Semen Microbiome by 16S Sequencing and Possible Relationships with Fertility

Reports on the use of 16S sequencing for the identification of bacteria in healthy animals are lacking. Bacterial contamination of bull semen can have a negative effect on the sperm quality. The aims of this study were threefold: to identify bacteria in the semen of healthy bulls using 16S sequencing; to investigate the differences in the bacterial community between individual bulls; and to establish if there was a relationship between the bacteria isolated and bull fertility. Semen from 18 bulls of known fertility was used for the DNA extraction and 16S sequencing; 107 bacterial genera were identified. The differences in the amplicon sequence variants (ASVs) and the numbers of genera between bulls were noted. Negative correlations (p < 0.05) between several bacterial genera with Curvibacter, Rikenellaceae RC9-gut-group and Dyella spp. were seen. Other negatively correlated bacteria were Cutibacterium, Ruminococcaceae UCG-005, Ruminococcaceae UCG-010 and Staphylococcus, all within the top 20 genera. Two genera, W5053 and Lawsonella, were enriched in bulls of low fertility; this is the first time that these bacteria have been reported in bull semen samples. The majority of the bacteria were environmental organisms or were species originating from the mucous membranes of animals and humans. The results of this study indicate that differences in the seminal microbiota of healthy bulls occur and might be correlated with fertility.

Effect of pegbovigrastim on fertility and culling in grazing dairy cows and its association with prepartum nonesterified fatty acids

This randomized controlled trial on 4 commercial grazing dairy farms investigated whether treatment with pegbovigrastim (PEG) affected fertility and culling as measured during the full lactation. We also explored the effect of potential interactions of PEG treatment with parity, prepartum body condition score, prepartum nonesterified fatty acid concentration (pre-NEFA), and early-lactation clinical disease on these outcomes. Holstein cows were randomly assigned to 1 of 2 trial arms: a first PEG dose approximately 7 d before the expected calving date and a second dose within 24 h after calving (PEG: primiparous = 342; multiparous = 697) compared with untreated controls (control: primiparous = 391; multiparous = 723). Cox's proportional hazards regression models were used to analyze rate of first insemination, rate of pregnancy [within 150 and 305 d in milk (DIM)], and hazard of culling. Additional analyses were performed on data that were stratified by parity group and pre-NEFA class (low ≤0.3; high >0.3 mM). In high pre-NEFA cows, PEG treatment increased the rate of first insemination [hazard ratio (HR) = 1.15]. Early-lactation clinical mastitis (CM) and uterine disease (UD: retained placenta, metritis, or both) were associated with a reduced rate of pregnancy within 150 DIM (HR = 0.49 and 0.78, respectively). Pegbovigrastim treatment in high pre-NEFA cows with CM and UD increased the rate of pregnancy within 150 DIM (HR = 1.75 and 1.46, respectively). In high pre-NEFA cows, PEG treatment resulted in a lower hazard of culling (HR = 0.79). No treatment effect was detected in low pre-NEFA cows. This study shows that the effect of PEG treatment on fertility and culling interacts with pre-NEFA. In high pre-NEFA cows, PEG treatment increased the rate of first insemination, counteracted the negative association of early-lactation CM and UD with the rate of pregnancy, and decreased the hazard of culling.

Prevention of retained fetal membranes and improvement in subsequent fertility with oxytocin administration in cows with assisted calving

In dairy cows, the efficacy of oxytocin treatment for preventing retained fetal membranes (RFM) is controversial. The physiological condition of cows associated with the calving process may affect the action of oxytocin. This study aimed to elucidate the difference in the efficacy of exogenous oxytocin treatment immediately after calving among cows that received various obstetric interventions. The calving ease was recorded using a score of 1-5, and assisted birth was defined as a score of 2 or more. Cows that required calving assistance (assisted, n = 28) due to delayed calving progression had a prolonged time from calving to expulsion of the fetal membrane (P < 0.01), and impaired reproductive performance compared to cows that did not receive calving assistance (unassisted, n = 78). The effect of oxytocin treatment was determined using cows that did not expel their fetal membrane within 3 h after calving. Cows were randomly divided into the control (unassisted, n = 41; assisted, n = 22) or oxytocin group (unassisted, n = 33; assisted, n = 10). Oxytocin (50 IU) was administered intramuscularly to the cows in the oxytocin group between 3 and 6 h after calving, while no treatment was administered in the control group. In cows with assisted birth, oxytocin administration accelerated placental expulsion (P < 0.05) and improved several reproductive parameters, such as the number of services until conception (P < 0.05) and the calving to conception intervals (P < 0.05) compared to the control group. On the other hand, oxytocin administration slightly accelerated placental expulsion (P < 0.05), but failed to improve fertility in cows with unassisted birth. The results indicate that the action of oxytocin varies depending on the calving situation of the cows. Oxytocin administration during the early postpartum period could prevent RFM and improve the decline in reproductive performance associated with calving assistance.

Assessing the consequences and economic impact of retained placenta in Holstein dairy cattle

Retained placenta (RP) is as an important reproductive disorder which adversely affects the economic performance of dairy cows. Understanding the consequences and economic losses associated with RP can persuade dairy farmers to consider it more effectively in their management decisions. Hence, the aims of this research were to assess the effect of RP on production and reproduction attributes as well as economic losses in Iranian Holstein cows. The data was collected from nine Holstein dairy herds in Isfahan province of Iran. The final dataset comprised of 139,508 records of 58,086 cows which calved between March 2011 and December 2018. A linear mixed model was developed to evaluate the effect of RP on individual performance of primiparous and multiparous cows. The economic losses associated with the RP were finally estimated. The average incidence of RP per cow over a year was 12.3% (ranged between 9.0 and 15.4%). Each incidence of RP significantly reduced milk, fat and protein yields in primiparous and multiparous cows (P < 0.05). The adverse effect of RP on the milk production was much higher in the cows at the early phase of lactation (i.e. 100-d lactation group) than the cows in mid or late lactation. The estimated production losses (±standard deviation) due to the RP event were 282.1 ± 43.0 and 295.7 ± 40.8 kg per cow for a 305-d lactation period in primiparous and multiparous cows, respectively. However, the fertility performance was less affected by the RP in primiparous compared to multiparous cows. The average of days open increased by 8.3 ± 5.3 and 19.8 ± 7.1 d in primiparous and multiparous cows, respectively. The financial losses associated with RP were on average US$ 350.4 and US$ 481.2 per incidence in primiparous and multiparous cows, respectively, ranged from US$ 311.9 to 456.2 depending on the parity number (primi- or multiparous) and herd management. The highest financial losses due to RP were associated with reduction in milk production (38.5% of total loss) and low fertility (28.5% of total loss) had the highest contribution in in primiparous and multiparous cows, respectively. The results of our research highlight the economic importance of improved calving management to reduce RP occurrence in dairy cows.

Predictive models to identify Holstein cows at risk of metritis and clinical cure and reproductive/productive failure following antimicrobial treatment

Precision dairy farming, specifically the design of management strategies according to the animal's needs, may soon become the norm since automated technologies that generate large amounts of data for each individual are becoming more affordable. Our objectives were to determine whether the use of behavioral changes could improve the accuracy of prediction of the risk of metritis and the risk of clinical cure of cows diagnosed with metritis. Addition of behavioral data to the algorithms to predict the outcomes of interest increased their accuracy by 7 to 32%. The incidence of metritis in postpartum dairy cows ranges from 20 to 40%. Unfortunately, approximately 30% of cows treated with antimicrobials following the diagnosis of metritis fail to cure and have impaired reproductive performance. Automated behavior monitoring devices have become more affordable and accessible. In the current study, we investigated whether behavioral changes recorded by automated devices improve models for the prediction, within 42 h of calving, of metritis and acute metritis. Furthermore, we determined whether behavioral changes aid on the prediction, 24 h before the diagnosis of metritis, of cure in response to antimicrobial treatments and the reproductive (failure to become pregnant)/productive (bottom quartile of milk yield) success within 200 d in milk (DIM). At enrollment, Holstein cows (n = 555) from two farms were fitted with an automated device (HR-LDn tag, SCR Engineers Ltd., Netanya, Israel) 21 d before the expected calving date. Cows were examined for metritis (fetid, watery, red/brown uterine discharge) and were randomly assigned to receive ampicillin trihydrate or ceftiofur crystalline free acid treatments. Contemporary cows with no clinical diseases (NoCD = 362) were paired with cows with metritis. Cure from metritis was defined as the absence of fetid, watery, pink/brown uterine discharge and rectal temperature < 39.5 °C, 11 d after diagnosis. In addition, cows in the lowest quartile of milk production, within lactation and farm, and that were not pregnant by 200 DIM were classified as failure. We built models containing: routinely-available data [lactation number (1, 2, ≥3), calf sex, still birth, twining, dystocia, vaginal laceration score, days on the close-up diets], body condition score (BCS) and BCS change from enrollment to calving (ΔBCS), behavior (feeding, rumination, idle, and active time), and their interactions. The area under the curve (AUC) of the models containing routinely-available data, ΔBCS, and behavior data at 2 DIM to predict metritis [AUC = 0.82, 95% confidence interval (CI) = 0.78, 0.85] and acute metritis (AUC = 0.87, 95% CI = 0.83, 0.89) were (P < 0.01) excellent; whereas the models predicting cure (AUC = 0.92, 95% CI = 0.85, 0.95) and failure (AUC = 0.90, 95% CI = 0.84, 0.94) were outstanding. Behavioral changes peripartum contribute for the identification of cows at risk for metritis, allowing the development of preventive strategies. In addition, predicting whether cows will respond to antimicrobial treatment and succeed during lactation may allow for earlier decision-making regarding treatment and culling.

Mechanisms by which mastitis affects reproduction in dairy cow: A review

Reproductive performance is a key factor in determining the profitability of dairy farm, which is affected by many factors such as environment and diseases. Mastitis is a common and important disease, which has caused huge economic losses to the dairy industries worldwide. Mammary gland infection causes immune responses, resulting in the abnormal secretion of cytokines and hormones and abnormal function of the reproductive system such as the ovary, corpus luteum, uterus and embryo. Cows with mastitis have delayed oestrus, decreased pregnancy rate and increased risk of abortion. The adverse effects of mastitis on reproductive performance are affected by many factors, such as occurrence time, pathogen and cow factors. This paper primarily reviews the progress in the effects and mechanisms of mastitis on reproductive performance, with emphasis on maternal transcriptome, genomic analysis, epigenetic modification, microbiota, inflammatory regulation and immune evasion mechanism of mastitis, aiming to provide directions for the prevention and control of mastitis in the future.

Using vaginal discharge score (VDS) grading system to evaluate the effect of clinical endometritis on reproductive performance of dairy cows in China

Clinical endometritis (CE) is a major cause in affecting the reproductive performance of dairy cows. The objectives of this study were to ascertain the prevalence of CE and to evaluate the effect of CE on reproductive performance in dairy cows using vaginal discharge score (VDS) grading system. 803 dairy cows were examined by vaginoscope with 4-point VDS at 26 ± 3 days in milk (DIM) and classified into six groups: non-endometritis with VDS 0 (control; CON), endometritis with VDS 1 (MEM), non-treated endometritis with VDS 2 (NTME), treated endometritis with VDS 2 (TME), non-treated endometritis with VDS 3 (NTPE), and treated endometritis with VDS 3 (TPE). Cows in TME and TPE groups were treated with 200 mL of 50% dextrose solution by intrauterine infusion. The prevalence of CE was 33% at 26 ± 3 DIM. Binary logistic regression analysis revealed cows in MEM, NTME and NTPE groups had a less likelihood of first artificial insemination (AI) pregnancy than those in CON group (P < 0.05). Kaplan-Meier survival curves for days open were statistically different (P = 0.004). In Cox regression model, cows in NTME and NTPE groups had a reduced pregnancy rate than those in CON group (P < 0.05). The hazard of pregnancy in NTME group was lower than that in TME group (P = 0.044). Similarly, it was lower for the hazard of pregnancy in NTPE group than in TPE group (P = 0.048). Cows in MEM, NTME, and NTPE groups required more services per pregnancy than those in CON group (P < 0.05). In conclusion, CE examined by the VDS grading system impaired reproductive performance, and mild endometritis with VDS 1 should be treated in the early postpartum period to ameliorate fertility in dairy herds.

Effects of supplemental Bacillus subtilis, injectable vitamin E plus selenium, or both on health parameters during the transition period in dairy cows in a tropical environment

The objective of this study was to determine the effects of supplemental Bacillus subtilis (BS, 0.5 × 10¹¹ CFU/day), injectable vitamin E and selenium (ES, 1000 mg α-tocopherol acetate and 10 mg sodium selenite), or both during the transition period on health parameters and the incidence of retained fetal membranes (RFM) of dairy cows under tropical conditions (average temperature humidity index = 77.0). Thirty-two crossbred Holstein-Friesian cows were used in a randomized design trial with a 2 × 2 factorial arrangement of treatments. Cows were randomly assigned to one of four treatments, including no supplementation (CON), single intramuscular injection of ES on day - 21 before the expected calving date (ES), daily oral supplementation of BS between day - 21 and day 21 relative to calving, or both ES and BS. Body condition score (BCS) and blood samples were collected on days - 28, - 14, 0, 14, and 28 relative to calving. Mean concentrations of corpuscular hemoglobin were higher (33.12 vs 34.03 g/dL, p = 0.06) and platelets were lower (380.97 vs 302.32 × 10³/μL, p = 0.10) with ES than without ES. Cows fed supplemental BS had lower concentrations of creatinine and albumin and tended to have lower AST and β-hydroxybutyrate (BHBA) levels. However, concentrations of glucose were higher for cows fed BS than for those without BS. No differences in the incidence of RFM were observed. In summary, supplemental B. subtilis could reduce indicators of negative energy balance by increasing glucose and lowering BHBA and improve health parameters by keeping WBCs and monocytes in a healthy range during the transition period.

Influence of Calving Ease on In-Line Milk Lactose and Other Milk Components

The aim of our study was to determine how the ease of calving of cows may influence changes in lactose concentration and other milk components and whether these two factors correlate with each other. To achieve this, we compared data of calving ease scores and average percentage of in-line registered milk lactose and other milk components. A total of 4723 dairy cows from nine dairy farms were studied. The cows were from the second to the fourth lactation. All cows were classified according to the calving ease: group 1 (score 1)-no problems; group 2 (score 2)-slight problems; group 3 (score 3)-needed assistance; group 4 (score 4)-considerable force or extreme difficulty. Based on the data from the milking robots, during complete lactation we recorded milk indicators: milk yield MY (kg/day), milk fat (MF), milk protein (MP), lactose (ML), milk fat/lactose ratio (MF/ML), milk protein/lactose ratio (MP/ML), milk urea (MU), and milk electrical conductivity (EC) of all quarters of the udder. According to the results, we found that cows that had no calving difficulties, also had higher milk lactose concentration. ML > 4.7% was found in 58.8% of cows without calving problems. Cows with more severe calving problems had higher risk of mastitis (SCC and EC). Our data indicates that more productive cows have more calving problems compared to less productive ones.

Effects of postpartum acetylsalicylic acid on uterine diseases and reproductive performance in dairy cattle

Uterine diseases are some of the most prevalent and costly diseases for the dairy industry. It has been reported that an exacerbated and prolonged inflammatory response around calving can increase the risk of developing metritis, which subsequently can impair production and fertility in dairy cows. The objective of this study was to assess the effects of 2 oral administrations of acetylsalicylic acid 24 h apart on the incidence of uterine diseases [i.e., retained fetal membranes, clinical metritis, clinical endometritis) and reproductive performance [i.e., days in milk to conception, number of services to conception, proportion of cows pregnant at first service, proportion of abortion at first service (ABRT)] in dairy cows after calving. Cows from one dairy farm (n = 246) located in central Pennsylvania were included in this study. Animals were blocked by parity and randomly assigned to 1 of 2 groups: (1) ASA (n = 121): within ~12 h after parturition, cows received 2 treatments with acetylsalicylic acid (ASA; 200 mg/kg, 4 boluses) 24 h apart; or (2) UNT (n = 125): cows remained untreated. Clinical metritis was assessed at 7 ± 3 and 14 ± 3 d in milk (DIM) using a Metricheck device (Simcro Tech Ltd., Hamilton, New Zealand). Cows that presented a fetid, red-brownish, watery vaginal discharge were classified as having clinical metritis. Clinical endometritis was assessed through ultrasonography and defined as presence of hyperechoic fluid (>3 mm) in the uterus lumen at 50 ± 10 DIM. The incidence of retained fetal membranes was defined as the failure of expulsion of the placenta within 24 h after calving and recorded by farm personnel. The data were analyzed using the MIXED and GLIMMIX procedures of SAS (SAS Institute Inc., Cary, NC) as a randomized complete block design. A lower proportion of cows treated with acetylsalicylic acid developed clinical metritis at 7 ± 3 DIM (ASA = 34.97 ± 5.57%; UNT = 57.21 ± 5.80%) and tended to develop clinical endometritis at 50 ± 10 DIM (ASA = 3.84 ± 2.67%; UNT = 13.61 ± 5.23%) compared with cows that remained untreated. Cows treated with acetylsalicylic acid tended to require 18 d less to conceive compared with UNT cows (ASA = 125.63 ± 8.21 d; UNT = 143.44 ± 6.28 d). Furthermore, there was a tendency for a treatment × ABRT interaction, whereby ASA cows that aborted at first service tended to conceive 35 d sooner compared with UNT cows that aborted at first service (ASA = 151.42 ± 15.90 d; UNT = 186.38 ± 11.84 d). Although there was no difference in pregnancy per AI at first service between treatment groups (ASA = 23.88 ± 7.92%; UNT = 17.93 ± 6.31%), the proportion of cows aborting at first service in the ASA group tended to be lower than that in the UNT group (ASA = 1.03 ± 1.06%; UNT = 6.04 ± 2.62%). Results from this study suggest that a short-duration acetylsalicylic acid treatment after calving may decrease the incidence of uterine diseases and improve reproductive success in cows that aborted at first service in dairy cattle.

Maintaining Optimal Mammary Gland Health and Prevention of Mastitis

In dairy industry, quality of produced milk must be more important than quantity without a high somatic cells count (SCC) or pathogens causing mastitis of dairy cows and consumer diseases. Preserving the good health of dairy cows is a daily challenge for all involved in primary milk production. Despite the increasing level of technological support and veterinary measures, inflammation of the mammary gland–mastitis, is still one of the main health problems and reasons for economic losses faced by cow farmers. The mammary gland of high-yielding dairy cows requires making the right decisions and enforcing the proper measures aimed at minimizing external and internal factors that increase the risk of intramammary infection. Due to the polyfactorial nature of mastitis related to its reduction, the effectiveness of commonly used antimastitis methods tends to be limited and therefore it is necessary to find the areas of risk in udder health programs and monitoring systems. Only by implementing of complete udder health programs should be accompanied by research efforts to further development these complete udder health control. The present review analyses the current knowledge dealing with damping and prevention of mastitis include SCC control, proper nutrition, housing and management, milking and drying as practiced in dairy farming conditions. This information may help to improve the health of the mammary gland and the welfare of the dairy cows as well as the production of safe milk for consumers.

Prepartum behavior changes in dry Holstein cows at risk of postpartum diseases

The objective of this study was to identify changes in prepartum behavior associated with the incidence of postpartum diseases in dairy cows. Multiparous Holstein cows (n = 489) were monitored with accelerometers for 3 wk prepartum. Accelerometers measured steps, time at the feed bunk, frequency of meals, lying bouts, and lying time. Postpartum health was monitored from 0 to 30 d in milk and cases of metritis, mastitis, retained placenta, displaced abomasum (DA), ketosis, and hypocalcemia were recorded. A multivariate linear mixed model was used to assess differences in behavior between diseased and not diagnosed diseased cows. A multivariate logistic regression was used to predict the occurrence of diseases. Predictors were selected using a manual backward stepwise selection process of variables until all remaining predictors had a P < 0.10. Models were submitted to a leave-one-out cross-validation process, and sensitivity, specificity, false discovery rate, and false omission rate were calculated. On average, over the 3-wk prepartum period, cows not diagnosed diseased (n = 345) took 1,613 ± 38 steps, spent 181 ± 7.1 min at the feed bunk, had 8.3 ± 0.17 meals, had 9.8 ± 0.32 lying bouts, and spent 742 ± 11.3 min lying per day. Behavior of diseased cows (n = 144) did not differ from those not diagnosed diseased. However, differences for specific diseases were observed, being significant in the week prepartum. When considering changes in behavior for only the week before calving, cows with metritis had more lying bouts (+21%), cows with DA had fewer meals (-24%) and tended to take fewer steps (-18%), and cows with ketosis had fewer meals (-22%) and spent less time at the feed bunk (-40%). Prediction models with the best outcomes were found for DA and ketosis using data of the prepartum week only. The model for DA included time at the feed bunk. Cross-validation resulted in a 80% sensitivity, 58.1% specificity, 59.2% accuracy, 91.2% false discovery rate, and 1.7% false omission rate. The model for ketosis included time at the feed bunk and number of meals. Cross-validation resulted in 64.3% sensitivity, 59.3% specificity, 59.5% accuracy, 93.0% false discovery rate, and 2.8% false omission rate. Prepartum behavior of cows affected with metritis, DA, and ketosis was different from that of cows not diagnosed with diseases. Prediction equations were able to classify cows at high or low risk of ketosis and DA and can be used in taking management decisions, but the high false discovery rates requires further refinement.

Metritis in dairy cows is preceded by alterations in biochemical profile prepartum and at parturition

Metritis in dairy cows is classified as a puerperal disease that affects all layers of the uterine epithelium and occurs during the first 21 days after parturition. The objectives of this study were to identify potential predictive biomarkers of metritis, to monitor the biochemical profile of pre-metritic dairy cows, and to evaluate the reproductive performance of dairy cows with metritis. Fifty-five cows without metritis and fifteen cows that showed clinical signs of metritis were enrolled in this study. Blood samples were collected at -21, -14 and - 7 days before calving and at parturition and assayed for urea, creatinine, aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), total cholesterol, fibrinogen, total calcium, β-hydroxybutyrate (BHB) and non-esterified fatty acids (NEFA) concentrations. Serum fibrinogen on 21, 14 and 7 days prepartum and at parturition was the strongest discriminator between metritic and control cows. Moreover, metritic cows had lower (P < 0.05) concentrations of urea, creatinine, cholesterol and calcium and higher (P < 0.05) serum AST, GGT activities, and serum fibrinogen, BHB and NEFA concentrations when compared to control cows. The number of days to first ovulation, insemination, services per pregnancy and days to pregnancy were greater (P < 0.05) for metritic cows than the control group, and the follicle size was smaller (P < 0.05) for metritic cows than the control group. Our results indicate alterations in the biochemical profile of dairy cows with metritis and the negative impact on the reproductive performance of metritic cows raised in tropical conditions. In addition, this study showed that the serum fibrinogen could be used as screening biomarkers to indicate cows that might have metritis during the postpartum period.

Retained bovine placenta - various treatments and their effects

Given the influence of retentio secundinarum (RS) on the reproductive performance of cows, the current work aimed to assess the effect of various approaches to the treatment of retained placenta on the main reproductive parameters, primarily on the interval from parturition to the first service, and the insemination index. The trial involved 120 dairy cows in which the placenta was not expelled within 24 h postpartum. The first group (G1, n=60) contained cows in which the retained placenta was not extirpated, but they were administered antibiotics. The second group (G2, n=60) comprised cows in which the placenta was removed manually, and were also administered antibiotics. At the end of the study, 53 cows remained in G1 and 54 cows in G2. According to medicament therapy, both groups were divided into three sub-groups treated with: procaine benzylpenicillin, chlortetracycline hydrochloride or ceftiofur. Comparison of the performance of G1 and G2 cows showed significantly better fertility parameters occurred in the animals from which the retained placenta was extracted manually. The pregnancy rate in the G2 group was remarkably higher than in the G1 group. The average service interval was significantly lower (p<0.05) in the G2 group compared to the G1 group. The best results were obtained with the i.m. administration of ceftiofur after the removal of the placenta.

Analysis of culling reasons and age at culling in Australian dairy cattle

Context A thorough analysis of the reasons for culling was made to understand the phenotypic trend in herd life. In addition, identification of culling reasons could enable to develop a strategy for further evaluation of longevity in Australian dairy cows. Aims The aim of this study was to investigate the main causes of culling in Australian dairy herds and thereby to assess the trend of reason-specific culling over time. Methods Culling reasons in Australian dairy cattle were studied based on culling records from 1995 through 2016. A total of 2452124 individual cow culling observations were obtained from Datagene, Australia, of which 2140337 were Holstein and 311787 were from Jersey cows. A binary logistic regression model was used to estimate effects of breed and age and the trend of a particular culling reason over time. Key results The most important culling reasons identified over the 21-year period were infertility (17.0%), mastitis (12.9%), low production (9.3%), sold for dairy purpose (6.4%) and old age (6.2%), whereas 37.4% were ‘other reasons not reported’. The average age at culling was nearly the same for Holstein (6.75 years) and Jersey (6.73 years) cows. The estimated age at culling was slightly increased for Holstein cows (by 3.7 days) and somewhat decreased for Jersey cows (by 11 days) over the last two decades. The probability of culling cows for infertility and low production was high in early parities and consistently declined as age advanced, and culling due to mastitis was higher in older cows. The trend of main culling reasons over time was evaluated, indicating that the probability of culling due to infertility has progressively increased over the years in both breeds, and culling for mastitis in Jersey cows has also increased. Culling of cows due to low production sharply decreased from 2.5 to –8% for Holstein and from 73 to 60% for Jersey cows over the 21-year period. Conclusions Culling age has changed only little in both breeds whereas culling reasons have changed over the last two decades, with low production becoming a less important reason for culling and infertility becoming more important for Holstein and Jersey breeds. Implications Due to changes of culling reasons, there could be a change in the meaning of survival over time as well. As a result, genetic correlation with survival and other traits might be changed and accuracy and bias of genetic evaluations could be affected.

Histopathological and cytological analyses of endometrium in water buffaloes (Bubalus bubalis) to detect estrus and endometritis

This study aimed to determine cytological, histopathological and cytomorphometrical characteristics of endometrium in healthy and endometritic uterus in the water buffalo. Fifty eight non-pregnant reproductive systems were collected from slaughterhouse. Efficiency of three methods of sampling including cotton swab, smear, and aspiration were compared for cytologic study. Concurrent histopathologic examination revealed endometritis in 38 uteri including 8 (21.00%) with mild endometritis, 7 (18.42%) with moderate endometritis, 6 (15.90%) with severe endometritis and 17 (44.73%) with chronic endometritis. Cyto-morphometrical results showed significant relationship between diameter and area of epithelial nuclei with phases of estrus cycle. Neutrophil and lymphocytes densities in swab and aspiration samples were significantly higher in severe endometritis than normal and chronic endometritis samples. Similarly, lymphocytes density in smear and aspiration methods was significant between normal and moderates, and also severe and chronic endometritis. Cytomorphometric analysis of epithelial nuclei characteristics (diameter and area) in buffalo were performed for the first time and it could be valuable to identify estrus cycle in this species. Aspiration had the most efficiency to identify endometritis in comparison with other methods.

Effects of metritis treatment strategies on health, behavior, reproductive, and productive responses of Holstein cows

Our objectives were to compare the effects of ceftiofur crystalline free acid (CCFA) and ampicillin trihydrate (AMP) treatments of cows diagnosed with metritis on uterine health, behavior, reproductive, and productive responses. A controlled randomized clinical trial was designed. Metritis was defined as vaginal discharge (VD) = 5 (fetid, watery, red/brown) within 21 d in milk (DIM) and rectal temperature (RT) <39.5°C, whereas VD = 5 and RT ≥39.5°C was defined as puerperal metritis. On the day of diagnosis (d 0), cows were paired by parity and severity of metritis (metritis vs. puerperal metritis) and assigned randomly to the AMP and CCFA treatments. Cows enrolled in the AMP (n = 308) treatment were moved to a nonsalable-milk pen, where they were treated once daily for 5 d, and were moved back to their original pen 72 h after the last treatment (d 7). Cows enrolled in the CCFA (n = 310) treatment remained in their original pen and received 2 treatments of CCFA, 72 h apart. Rectal temperature was measured daily from d 0 to 6 and on d 11. Vaginal discharge was evaluated on d 4, 6, and 11 to assess cure. Cure was defined as the absence of treatment with additional antimicrobial before experiment d 11, VD <5, and RT <39.5°C. Cows were examined at 28 ± 3 DIM for purulent VD (PVD) and at 35 ± 3 DIM for cytological endometritis. Pregnancy was diagnosed at 40 ± 3 and 60 ± 7 d after first and second artificial inseminations. Cure of metritis did not differ between treatments on d 11 (AMP = 64.6 ± 3.1, CCFA = 63.5 ± 3.1%). Cows treated with AMP had greater RT from experiment d 1 to 6 compared with cows treated with CCFA (AMP = 39.1 ± 0.02, CCFA = 39.0 ± 0.02°C). Cows in the AMP treatment had greater prevalence of PVD at 28 ± 3 DIM (AMP = 82.6 ± 2.3, CCFA = 74.4 ± 2.7%) and tended to have greater prevalence of cytological endometritis at 35 ± 3 DIM (AMP = 77.8 ± 6.2 vs. CCFA = 61.7 ± 7.5%) than CCFA-treated cows. Treatment did not affect the hazard of pregnancy among multiparous cows; however, among primiparous cows, CCFA treatment reduced the hazard of pregnancy and increased the median days to pregnancy (AMP = 145 vs. CCFA = 169 d). Finally, average daily milk yield up to 14 wk postpartum was not affected by treatment (AMP = 38.0 ± 0.4, CCFA = 37.5 ± 0.4 kg). We conclude from the current experiment that CCFA was more effective in reducing RT and improving uterine health of metritic cows; however, the improved hazard of pregnancy of primiparous cows treated with AMP is important and warrants further investigation.

Between-herd variation in resilience and relations to herd performance

Resilient cows are minimally affected in their functioning by infections and other disturbances, and recover quickly. Herd management is expected to have an effect on disturbances and the resilience of cows, and this effect was investigated in this study. Two resilience indicators were first recorded on individual cows. The effect of herd-year on these resilience indicators was then estimated and corrected for genetic and year-season effects. The 2 resilience indicators were the variance and the lag-1 autocorrelation of daily milk yield deviations from an expected lactation curve. Low variance and autocorrelation indicate that a cow does not fluctuate much around her expected milk yield and is, thus, subject to few disturbances, or little affected by disturbances (resilient). The herd-year estimates of the resilience indicators were estimated for 9,917 herd-year classes based on records of 227,655 primiparous cows from 2,644 herds. The herd-year estimates of the resilience indicators were then related to herd performance variables. Large differences in the herd-year estimates of the 2 resilience indicators (variance and autocorrelation) were observed between herd-years, indicating an effect of management on these traits. Furthermore, herd-year classes with a high variance tended to have a high proportion of cows with a rumen acidosis indication (r = 0.31), high SCS (r = 0.19), low fat content (r = -0.18), long calving interval (r = 0.14), low survival to second lactation (r = -0.13), large herd size (r = 0.12), low lactose content (r = -0.12), and high production (r = 0.10). These correlations support that herds with high variance are not resilient. The correlation between the variance and the proportion of cows with a rumen acidosis indication suggests that feed management may have an important effect on the variance. Herd-year classes with a high autocorrelation tended to have a high proportion of cows with a ketosis indication (r = 0.14) and a high production (r = 0.13), but a low somatic cell score (r = -0.17) and a low proportion of cows with a rumen acidosis indication (r = -0.12). These correlations suggest that high autocorrelation at herd level indicates either good or poor resilience, and is thus a poor resilience indicator. However, the combination of a high variance and a high autocorrelation is expected to indicate many fluctuations with slow recovery. In conclusion, herd management, in particular feed management, seems to affect herd resilience.

Milk losses and dynamics during perturbations in dairy cows differ with parity and lactation stage

Milk yield dynamics during perturbations reflect how cows respond to challenges. This study investigated the characteristics of 62,406 perturbations from 16,604 lactation curves of dairy cows milked with an automated milking system at 50 Belgian, Dutch, and English farms. The unperturbed lactation curve representing the theoretical milk yield dynamics was estimated with an iterative procedure fitting a model on the daily milk yield data that was not part of a perturbation. Perturbations were defined as periods of at least 5 d of negative residuals having at least 1 day that the total daily milk production was below 80% of the estimated unperturbed lactation curve. Every perturbation was characterized and split in a development and a recovery phase. Based hereon, we calculated both the characteristics of the perturbation as a whole, and the duration, slopes, and milk losses in the phases separately. A 2-way ANOVA followed by a pairwise comparison of group means was carried out to detect differences between these characteristics in different lactation stages (early, mid-early, mid-late, and late) and parities (first, second, and third or higher). On average, 3.8 ± 1.9 (mean ± standard deviation) perturbations were detected per lactation in the first 305 d after calving, corresponding to an estimated 92.1 ± 135.8 kg of milk loss. Only 1% of the lactations had no perturbations. On average, 2.3 kg of milk was lost per day in the development phase, while the recovery phase corresponded to an average increase in milk production of 1.5 kg/d, and these phases lasted an average of 10.1 and 11.6 d, respectively. Perturbation characteristics were significantly different across parity and lactation stage groups, and early and mid-early perturbations in higher parities were found to be more severe with faster development rates, slower recovery rates, and higher milk losses. The method to characterize perturbations can be used for precision phenotyping purposes that look into the response of cows to challenges or that monitor applications (e.g., to evaluate the development and recovery of diseases and how these are affected by preventive actions or treatments).

Postpartum uterine diseases negatively impact the time to pregnancy in grazing dairy cows from high-altitude tropical herds

Infertility is a common consequence of cows suffering from postpartum uterine diseases. Diseases from a uterine origin in early lactation affect both uterine and ovarian tissues decreasing the probability of pregnancy. The objective of the present study was to determine the impact of clinical metritis, clinical endometritis, and subclinical endometritis on days open in cows from high-altitude tropical dairy herds. A single cohort longitudinal study was conducted from January 2018 to February 2019, which included 248 cows enrolled from five commercial high-altitude tropical dairy herds in the northern region of the Department of Antioquia, Colombia. A directed acyclic graph was used to identify minimal sufficient adjustment sets for each exposure variable of interest. Based on the directed acyclic graph, three models (one for each of clinical metritis, clinical endometritis, and subclinical endometritis) were proposed to assess the impact of postpartum uterine diseases on days open. The time at risk was defined as the days elapsed from calving until pregnancy (event or censure). Observations were right-censored if cows were either culled, dead, were lost to follow up, suffered a systemic illness that required the use of parenteral drugs, or if they were not pregnant at 210 postpartum days. Three Cox proportional hazards models were proposed to estimate the Hazard Ratios (HR) at any point in the follow-up period for each exposure variable. The hazard of pregnancy was significantly lower for cows with metritis (40 %; HR = 0.60; 95 % CI: 0.43 - 0.86), clinical endometritis (69 %; HR = 0.31; 95 % CI: 0.22 - 0.45), and subclinical endometritis (76 %; HR = 0.24; 95 % CI: 0.16 - 0.36) compared to their herd mates without these conditions. These results provide evidence of the negative impact of postpartum uterine diseases on time to pregnancy in grazing lactating dairy cows from high-altitude tropical herds.