Reproductive disorders in the periparturient dairy cow

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 estimates for lactational incidence or prevalence or both, 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 US$65 billion (B). Subclinical ketosis, clinical mastitis, and subclinical mastitis were the costliest diseases modeled, resulting in mean annual global losses of approximately US$18B, US$13B, and US$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 US$0.2B, US$0.6B, US$0.6B, US$6B, US$5B, US$0.6B, US$4B, US$4B, and US$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 (US$12B), the United States (US$8B), and China (US$5B), depending on the measure of losses used (losses as a percentage of gross domestic product, losses per capita, losses as a percentage of gross milk revenue), the relative economic burden of these dairy cattle diseases across countries varied markedly.

Association between non-esterified fatty acids and calcium concentrations at calving with early lactation clinical diseases, fertility and culling in grazing dairy cows in Uruguay

This study describes the association of non-esterified fatty acids (NEFA) and calcium concentrations at calving with early lactation disease, reproductive performance and culling in 646 dairy cows from 13 commercial grazing dairy herds in Uruguay. During one year, health events were recorded from calving to 30 days in milk (DIM). The first author visited each farm every 20 days. During each visit, body condition score (BCS) was recorded (scale 1-5), defining BCS < 3 as suboptimal and BCS > 3 as optimal, and a blood sample was taken from cows between 0 and 4 DIM for metabolite determination. To evaluate the association between health events (i.e., retained placenta-metritis and clinical mastitis) and risk factors (parity, BCS, high NEFA (> 0.6 mmol/L) and subclinical hypocalcemia (SCH) (< 2.10 mM)) data were analysed using multivariable logistic regression models. To evaluate the association of health events and risk factors with reproductive performance and culling, data were analysed using Cox proportional hazard regression models. A risk factor and an outcome of interest were assumed to be associated at P < 0.05 and a tendency to be associated was defined at P < 0.10. Overall, 47 % (n = 303) of the cows showed elevated NEFA concentration and 77 % (n = 499) had SCH. In addition, 21.5 % (n = 139) of the cows recorded at least one clinical disease. Cumulative incidence was 17 % (n = 109) for clinical mastitis, 4.2 % (n = 27) for retained placenta (RP)-metritis and 1.4 % (n = 7) for lameness. Clinical mastitis was associated with parity, with lower odds in primiparous (PP) cows (OR = 0.42, P < 0.01). Cows in an optimal BCS also tended to have lower odds (OR = 0.66, P = 0.07). Moreover, high NEFA and SCH cows had higher odds of CM (OR = 4.5, P = 0.01 and OR = 1.75, P = 0.04, respectively). Retained placenta-metritis tended to be associated with high NEFA concentration (OR = 2.2, P = 0.06). Primiparous cows with suboptimal BCS showed an increased first insemination rate (HR = 2.34; P < 0.01). The risk of culling was lower in PP cows (HR = 0.19; P < 0.01) and in cows with optimal BCS and low NEFA concentration (HR = 0.38; P = 0.03). Our data show that metabolic challenge (defined as peripartum suboptimal BCS, high NEFA or SCH) is associated with increased odds of clinical mastitis and RP-metritis, decreased probability of insemination and increased hazard of culling. Under grazing conditions, we suggest that farm management to improve the metabolic adaptation to lactation represents an opportunity to enhance cow performance in terms of health, fertility and longevity.

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.

Transition cow metabolites and physical traits influence days to first postpartum ovulation in dairy cows

Physical activities are associated with the health of transition dairy cows and pregnancy outcomes are positively related to early resumption of postpartum estrous cycles. The objective was to assess key metabolites and patterns of prepartum and postpartum physical activity as they relate to the onset of first postpartum ovulation in lactating dairy cows. Close-up dry Holstein cows (n = 82) and late gestation heifers (n = 78) were enrolled beginning 3 wk before expected calving date (Day 0). Cows were fit with Cow SensOor ear tags to assess transitional changes in eating, resting, rumination, high activity, and ear-surface temperatures. Rectal temperatures were assessed and blood samples were collected on Days 0, 3, 7, and 14 to measure concentrations of glucose, free fatty acids (FFA), β-hydroxybutyrate (BHB), calcium, and haptoglobin. Body condition scores (BCS) and body weights (BW) were measured weekly, and blood samples were collected weekly from Day 21 ± 3 through 70 ± 3 to quantify changes in progesterone to detect luteal function after ovulation. Cows first ovulating before median Day 33 were classified as early (n = 76), whereas those first ovulating after Day 33 were classified as late (n = 84). Early ovulating cows first ovulated earlier (P < 0.001) than the late ovulation cows (24.3 ± 1.2 d [range: 16-32 d] vs. 48.8 ± 1.2 d [range: 33-74 d]), respectively. Mean days to first ovulation excluded seven cows that failed to ovulate before insemination. Compared with late ovulating cows, early ovulating cows had lesser (P < 0.05) concentrations of FFA, BHB, and haptoglobin on Days 0, 3, 7, and 14 in addition to having lesser (P < 0.05) rectal temperatures and ear-surface temperatures. Ear-surface temperatures began to decrease 4 d before parturition and remained less (P < 0.05) after calving than cows that subsequently ovulated late. Early ovulating cows tended (P = 0.07) to spend more time eating, and less (P = 0.02) time resting and being active during the first 3 wk after calving, and lost less (P = 0.03) BW and BCS during the first 9 wk compared with late ovulating cows. Although no differences were detected in yields of milk or energy-corrected milk during the first 9 wk after calving, early compared with late ovulating cows produced more (P < 0.01) milk protein. We concluded that metabolic measures during the first 2 wk after calving, and physical and behavioral traits are associated with the onset of postpartum ovarian activity.

Transition dairy cow health is associated with first postpartum ovulation risk, metabolic status, milk production, rumination, and physical activity

Our objective was to determine the association of health status during the first 60 d in milk (DIM) and first postpartum ovulation risk, physical activities recorded by an activity monitor, and metabolic and milk measures in Holstein cows. Late-gestation heifers and close-up dry cows in 1 herd fitted with CowManager SensOors (Agis, Harmelen, the Netherlands) were enrolled in the study 3 wk before expected parturition to assess ear skin temperature and daily rumination, eating, inactivity, and activity times. Blood samples were collected at calving (d 0), and on d 3, 7, and 14 to assess concentrations of free fatty acids, β-hydroxybutyrate (BHB), calcium, glucose, and haptoglobin. In addition, weekly measures were conducted for body condition, body weight, and progesterone through 63 ± 3 DIM when ovulation was synchronized (GnRH-1 - 7 d - PGF_2α - 24 h - PGF_2α - 32 h - GnRH-2 - 16 h - artificial insemination). Disease diagnosed in 68 of 160 cows (42.5%) was distributed equally between primiparous (48.5%) and multiparous (51.5%) cows. Cows were classified as diseased when any case of metritis, digestive disorders, ketosis, hypocalcemia, calving problems, mastitis, or lameness occurred during the first 60 DIM. Odds of early ovulation by median postpartum d 33 was 1.92 times greater in healthy than diseased cows. Incidence of individual diseases included metritis (18.8%), digestive disorders (17.5%), ketosis (BHB >10 mg/dL; 11.9%), hypocalcemia (Ca <2.2 mmol/L; 10.6%), calving problems (6.3%), mastitis (3.1%), and lameness (3.1%). Odds of early ovulation were 2.48, 2.65, and 5.72 times greater in healthy cows compared with cows diagnosed with metritis, digestive disorders, or ketosis, respectively. Diseased compared with healthy cows had greater concentrations of free fatty acids, BHB, haptoglobin, greater rectal temperature, and lesser concentration of serum calcium on d 0, 3, 7, and 14 than healthy cows. Plasma glucose was not affected by health status, but was lesser in concentration on d 3, 7, and 14 compared with day of calving. Weekly (calving through 9 wk) body condition scores tended to be and weekly body weights were greater in healthy compared with diseased cows. Activity measures differed by health status during prepartum (d -14 through -1) and postpartum (d 0 through 20) periods except for eating time. Healthy cows spent less time being inactive during both periods compared with diseased cows and had greater postpartum rumination times than diseased cows. Mean daily milk yield during the first 14 wk in milk was greater in healthy than diseased cows by 2.1 ± 0.8 kg. We conclude that disease negatively affects early postpartum ovulation risk and is associated with measurable changes in periparturient physical activity and postpartum metabolic profiles.

A Review of Welfare Indicators of Indoor-Housed Dairy Cow as a Basis for Integrated Automatic Welfare Assessment Systems

Simple Summary

Many techniques have been developed to measure single indicators of reduced welfare in farm animals, such as changes in the walking pattern to detect lameness in dairy cows. However, there is still a need to combine these single measurements to get a more complete picture of the wellbeing of an animal. Based on a literature review on dairy cow welfare, this review provides a basis for the development of an integrated automatic system to assess the welfare of dairy cows on the farm. It provides an overview of the main welfare issues for dairy cows, such as lameness, heat stress, or pain and of the most established indicators that could help to detect these welfare issues on the farm. We found that there are several indicators, such as reduced feed intake, that are common to most welfare issues and that are therefore suitable to detect reduced welfare in general, while other indicators mainly identify one welfare issue, such as increased respiratory rate, as an indicator of heat stress. Combining these different types of indicators would provide a good basis to develop an integrated automatic system that could assist farmers in the detection of reduced welfare on their farms.

Abstract

For on-farm welfare assessment many automatic methods have been developed to detect indicators of reduced welfare. However, there is still a need to integrate data from single sources to obtain a complete picture of the welfare of an animal. This review offers a basis for developing integrated automatic systems to assess dairy cow welfare by providing an overview of the main issues that challenge cow welfare (e.g., lameness) and of well-established indicators that could detect these issues on the farm. Based on a literature review of 4 reviews on cow welfare in general and 48 reviews on single welfare issues, we identified 18 different major welfare issues and 76 matching indicators that could be detected automatically on the farm. Several indicators, e.g., feed intake, showed a consistent association with welfare across many different issues. Although some of these indicators are discussed critically, this means there are many indicators that potentially could detect reduced welfare in general. Other types of indicators could detect one specific welfare issue, e.g., increased respiratory rate for heat stress. These different types of indicators combined provide a basis to develop integrated automatic systems that ultimately would help farmers to detect welfare problems at an early stage.

A review of vitamin D and its importance to the health of dairy cattle

This Research Reflection short review will discuss vitamin D metabolism, its role in nutrition, disease prevention, and welfare of dairy cattle, as well as its toxicity. Vitamin D is an important fat-soluble vitamin. However, some researchers regard it as a hormone due to its function in the organism. Its role is not limited just to Ca homoeostasis and bone metabolism but is also associated with immunity. In dairy cattle it is known for preventing milk fever. Cows can acquire vitamin D in many ways for example through feed, parenteral injections or through UVB irradiation from the sun or artificial lighting. The vitamin D in feed can either be plant-/ fungi- based ergocalciferol or animal-based cholecalciferol. There is currently only one registered feed vitamin D supplement for cattle in the European Union and it is cholecalciferol. Animals can also synthesize their own vitamin D when 7-dihydrocholesterol in the skin is irradiated with UVB light resulting in cholecalciferol production. Despite its importance, many cattle are deficient in vitamin D due to inadequate supplementation or insufficient sun exposure. In a study performed at the Veterinary Faculty in Slovenia 12 high producing Holstein Friesian cows at a commercial dairy farm were blood tested for vitamin D status for three succeeding months and all but one were vitamin D insufficient in all testings. The cows were not exposed to direct sunlight and the content of vitamin D3 in feed was <400 IU/kg dry matter, which is less than half of the NRC (2001) recommendation. Deficiency can also occur due to diseases affecting the gastrointestinal tract, such as paratuberculosis, which lower the absorptive capacity of the gut. Vitamin D can be toxic if cows are over-supplemented or consume large quantities of plants like Trisetum flavescens, which contain an active form of vitamin D-calcitriol or its glycosides, that are activated by digestion in the rumen.

A randomized controlled trial on the effect of incomplete milking during early lactation on ketonemia and body condition loss in Holstein dairy cows

Limiting milk production for a short period of time in early lactation could be a relevant strategy to prevent hyperketonemia (HYK). From December 2013 to March 2015, 838 multiparous Holstein cows from 13 herds were enrolled in a randomized controlled trial evaluating the effect of incomplete milking in early lactation on ketonemia and its effect on body condition score (BCS) loss. Cows were randomly assigned 4 wk before expected calving date to 1 of 2 treatment groups, (1) a conventional milking protocol (CON) for which cows were completely milked or (2) an incomplete milking protocol (INC) for which a maximum of 10 to 14 kg of milk/d were withdrawn during the first 5 d in milk (DIM). β-Hydroxybutyrate (BHB) concentrations were measured from blood samples collected on each cow 3 times at weekly intervals. Hyperketonemia was defined as BHB ≥1.4 mmol/L. Body condition score variation in the postcalving period was calculated by subtracting BCS assessed at wk 7 from BCS assessed at first week after calving. Effect of treatment on ketonemia and prevalence of HYK were evaluated for 4 specific time periods: 1 to 3, 4 to 7, 8 to 17, and 18 to 26 DIM. Effect of treatment on ketonemia was investigated using linear mixed models with natural logarithm of BHB measurements as outcome and treatment groups as fixed effect. Generalized linear mixed models with HYK as outcome, using logit link, and treatment groups as fixed effect were used to investigate effect of treatment on odds of HYK. A logistic regression model with BCS loss (<0.75 or ≥0.75) as outcome and treatment groups and herd as fixed effects was used to study effect of INC on odds of having BCS loss ≥0.75. A total of 813 lactations had complete data and were used for statistical analysis of ketonemia and HYK. A total of 709 lactations had complete data and were used for analysis of BCS loss. Geometric means of blood BHB concentrations during the 1 to 3, 4 to 7, 8 to 17, and 18 to 26 DIM periods were, respectively, 0.72 (95% confidence interval = 0.66, 0.80), 0.66 (0.60, 0.73), 0.90 (0.80, 1.01), and 0.93 (0.83, 1.05) mmol/L for INC, and 0.65 (0.59, 0.72), 0.79 (0.72, 0.87), 0.94 (0.84, 1.06), and 0.92 (0.82, 1.04) mmol/L for CON. Cows in INC group had lower ketonemia during the 4 to 7 DIM period. Predicted prevalence of HYK during the 1 to 3, 4 to 7, 8 to 17, and 18 to 26 DIM periods were, respectively, 2.8 (3.2, 15.1), 4.6 (2.0, 10.0), 13.4 (8.4, 20.0), and 23.0% (17.4, 29.7) for INC and 2.6 (2.5, 13.8), 10.7 (5.6, 19.3), 19.4 (13.0, 27.9), and 21.3% (16.0, 27.8) for CON. The INC treatment reduced the prevalence of HYK during the 4 to 7 and 8 to 17 DIM periods. No association was observed between INC and BCS loss in the postcalving period. Overall, the incomplete milking protocol was effective for reducing ketonemia and prevalence of HYK during the early postpartum period.

Performance and financial consequences of stillbirth in Holstein dairy cattle

Stillbirth is an economically important trait on dairy farms. Knowledge of the consequences of, and the economic losses associated with stillbirth can help the producer when making management decisions. The objectives of this study were to determine the effects of stillbirth on productive and reproductive performance as well as financial losses due to stillbirth incidence in Iranian Holstein dairy farms. Economic and performance data were collected from nine Holstein dairy farms in Isfahan and Khorasan provinces of Iran from March 2008 to December 2013. The final data set included 160 410 calving records from 53 265 cows. A linear mixed model was developed to evaluate the effects of stillbirth on performance of primiparous and multiparous cows separately and overall. An economic model was used to estimate the economic losses due to stillbirth. The incidence of stillbirth cases per cow per year was 4.2% on average (3.4% to 6.8% at herd level). The least square means results showed that a case of stillbirth significantly (P0.05). Overall, a case of stillbirth reduced 305-day milk yield by 544.0±76.5 kg/cow per lactation. Stillbirth had no significant effects on 305-day fat and protein percentages in either primiparous or multiparous cows. Overall, cows that gave birth to stillborn calves had significantly increased days open by 14.6±2.6 days and the number of inseminations per conception by 0.2 compared with cows that gave birth to live calves (P<0.01). In general, the negative productive and reproductive effects associated with stillbirth were smaller and non-significant for primiparous cows compared with multiparous cows. The financial losses associated with stillbirth incidence averaged US$ 938 per case (range from $US 767 to $US 1189 in the nine investigated farms). The loss of a calf was not the only cost associated with stillbirth, as it accounted for 71.0% of the total cost. The costs of dystocia (7.6%) and culling and replacement expenses (6.3%) were the next most important costs associated with stillbirth. These results can be used to assess the potential return from management strategies to reduce the occurrence of stillbirths.

Associations between activity of arginase or matrix metalloproteinase-8 (MMP-8) and metritis in periparturient dairy cattle

Metritis, a uterine disease caused by bacterial infection, is highly prevalent in dairy cattle after parturition. Uterine disease has negative effects on milk production and reproductive efficiency. Finding markers or indicators that can predict cows at greater risk for uterine disease could be beneficial to mitigating these deleterious effects. This study investigates the immune-derived enzymes arginase and matrix metalloproteinase-8 (MMP-8) as potential markers for development of metritis in dairy cows. In a retrospective matched case-control study, 53 lactating Holstein cows diagnosed with metritis were matched and paired to 53 lactating Holstein control cows. In addition to examining cows for diagnosis of metritis on d 4, 7, 10, and 14 after parturition, occurrence of retained fetal membranes, gender of the calf, and the event of a stillbirth were recorded. Blood samples were collected 7 ± 3 d before calving, on the day of calving, and 7 ± 3 d after calving and were assayed for activity of arginase and MMP-8. Associations between metritis and activity of arginase or MMP-8 were determined by conditional logistic regression at each individual sampling time point. An interaction between activity of arginase, before and on the day of parturition, and retained fetal membranes tended (P ≤ 0.13) to be associated with metritis. After parturition, activity of arginase and the interaction between activity of arginase and retained fetal membranes were not (P ≥ 0.22) associated with metritis. Activity of MMP-8 was not (P ≥ 0.20) associated with metritis in the periparturient period. Retained fetal membranes were associated with the odds of developing metritis. Activity of arginase before and at the time of parturition might be a potential marker for occurrence of metritis, especially in cows that develop retained fetal membranes. MMP-8 does not seem to be a potential indicator for metritis.

Effects of stillbirth and dystocia on subsequent reproductive performance in Japanese Black cattle

The objective of this study was to determine the effects of stillbirth and dystocia on subsequent reproductive performance in Japanese Black cattle. Data were collected for 34,763 calvings from 13,186 animals on 826 farms. Stillbirth was associated with a decreased first service conception rate compared to cows with a normal calving (44.4 versus 54.0%, respectively, P < 0.001). Cows with a normal calving required fewer artificial inseminations per conception and had a lower stillbirth rate at subsequent parity than those with stillbirth and dystocia (P < 0.001). Japanese Black cows with stillbirth and dystocia had inferior subsequent reproductive performance compared with those with a normal calving.

Evaluation of two doses of ceftiofur crystalline free acid sterile suspension for treatment of metritis in lactating dairy cows

The objectives of this study were to evaluate efficacy of a 2-dose regimen of ceftiofur crystalline free acid sterile suspension (CCFA-SS) for treatment of acute metritis in lactating dairy cows under field conditions and to provide additional safety and injection site tolerance data for injections at the base of the ear. Cows at 15 dairies with rectal temperature ≥ 39.5°C and fetid uterine discharge ≤ 10 d postcalving were randomly assigned by blocks of 2, based on order of entry and without regard to parity, to treatment with saline (1.5 mL/45.5 kg of body weight, n=509) or CCFA-SS (6.6 mg of ceftiofur equivalents/kg of body weight, n=514). Treatments were administered by subcutaneous injection in the posterior aspect of the ear where it attaches to the head; the first dose was administered on study d 0 and the second dose was administered in the contra lateral ear on study d 3. Rectal temperatures were recorded on study d 1 to 4 and 5 or 6 and cows were clinically evaluated daily from study d 1 to 13. Cows that exhibited increased adverse clinical signs of poor health or complications associated with metritis were categorized as a treatment failure and administered escape therapy. Each cow received a veterinary physical examination on study d 5 or 6 to determine if she should be removed from the study and on study d 14 to determine clinical cure or failure to cure. Clinical cure was defined as rectal temperature <39.5°C and non-fetid and purulent or mucopurulent discharge on study d 14 and no escape therapy administered. The injection procedure was scored after each injection (study d 0 and 3) and injection sites and ear carriage were scored on study d 5 or 6, 14, and 57±3. Of the 1,023 cows enrolled, 7 were completely censored due to protocol deviations and 34 were removed for protocol deviations or medical conditions not related to metritis. Clinical cure rate was higher for CCFA-SS than for saline (74.3 vs. 55.3%) and rectal temperatures for each of study d 1 to 5 or 6 were lower for CCFA-SS than saline. Injection procedure indices showed that CCFA-SS could be practically and safely administered using commercial dairy facilities. Although injection site scores were higher for CCFA-SS than saline at study d 5 or 6 and 14, ≥98.6% of ears were normal on d 57±3. Thus, a 2-dose treatment with CCFA-SS given 72h apart increased metritis clinical cure rate and was well tolerated in dairy cows.

Comparison of reproductive performance in Belgian dairy and beef cattle

A computerized program was written to collect, evaluate and compare reproductive performance data of 2004 beef (Belgian Blue breed) and 1649 dairy (Friesian Holstein and German Red) cattle in 35 Belgian herds (6 suckler beef herds, 9 milked beef herds and 20 dairy herds). Reproduction data were collected at monthly herd health visits. No difference in age at first calving was observed. Significant differences were observed among the 3 kinds of herds, and the best results were obtained in dairy herds for the calving interval, interval from calving to the first estrus, interval from calving to the first service and average number of days open. Concerning these parameters, first calvers had lower results than multiparous cows, mainly in suckler and milked beef herds. Significant differences were noted in the number of services per pregnancy. Heifers that had never calved presented the highest fertility. Primiparous beef cows had higher fertility than pluriparous cows. In dairy herds, pluriparous cows had higher fertility than primiparous cows. Estrus detection was better in milked beef herds than in suckled beef and dairy herds. Suckled beef herds had the lowest incidence of metritis and ovarian cysts of the three types of herds. Rates of abortion, overall culling and retained fetal membranes were similar in all the herds. The percentage of animals removed for infertility was highest in milked beef herds and lowest in dairy herds. Because 90% of the 1159 calvings recorded in the beef herds required a caesarean section, the reproductive performance of beef cattle represent results after caesarean section.

Management practices associated with conception rate and service rate of lactating Holstein cows in large, commercial dairy herds

Data from lactating Holstein cows in herds that participate in a commercial progeny testing program were analyzed to explain management factors associated with herd-average conception and service rates on large commercial dairies. On-farm herd management software was used as the source of data related to production, reproduction, culling, and milk quality for 108 herds. Also, a survey regarding management, facilities, nutrition, and labor was completed on 86 farms. A total of 41 explanatory variables related to management factors and conditions that could affect conception and service rate were considered in this study. Models explaining conception and service rates were developed using a machine learning algorithm for constructing model trees. The most important explanatory variables associated with conception rate were the percentage of repeated inseminations between 4 and 17 d post-artificial insemination, stocking density in the breeding pen, length of the voluntary waiting period, days at pregnancy examination, and somatic cell score. The most important explanatory variables associated with service rate were the number of lactating cows per breeding technician, use of a resynchronization program, utilization of soakers in the holding area during the summer, and bunk space per cow in the breeding pen. The aforementioned models explained 35% and 40% of the observed variation in conception rate and service rate, respectively, and underline the association of herd-level management factors not strictly related to reproduction with herd reproductive performance.

A novel method of analyzing daily milk production and electrical conductivity to predict disease onset

This study evaluates the changes in milk production (yield; MY) and milk electrical conductivity (MEC) before and after disease diagnosis and proposes a cow health monitoring scheme based on observing individual daily MY and MEC. All reproductive and health events were recorded on occurrence, and MY and MEC were collected at each milking from January 2004 through November 2006 for 587 cows. The first 24 mo (January 2004 until December 2005) were used to investigate the effects of disease on MY and MEC, model MY and MEC of healthy animals, and develop a health monitoring scheme to detect disease based on changes in a cow's MY or MEC. The remaining 11 mo of data (January to November 2006) were used to compare the performance of the health monitoring schemes developed in this study to the disease detection system currently used on the farm. Mixed model was used to examine the effect of diseases on MY and MEC. Days in milk (DIM), DIM x DIM, and ambient temperature were entered as quantitative variables and number of calves, parity, calving difficulty, day relative to breeding, day of somatotropin treatment, and 25 health event categories were entered as categorical variables. Significant changes in MY and MEC were observed as early as 10 and 9 d before diagnosis. Greatest cumulative effect on MY over the 59-d evaluation period was estimated for miscellaneous digestive disorders (mainly diarrhea) and udder scald, at -304.42 and -304.17 kg, respectively. The greatest average daily effect was estimated for milk fever with a 10.36-kg decrease in MY and 8.3% increase in MEC. Milk yield and MEC was modeled by an autoregressive model using a subset of healthy cow records. Six different self-starting cumulative sum and Shewhart charting schemes were designed using 3 different specificities (98, 99, and 99.5%) and based on MY alone or MY and MEC. Monitoring schemes developed in this study issue alerts earlier relative to the day of diagnosis of udder, reproductive, or metabolic problems, are more sensitive, and give fewer false-positive alerts than the disease detection system currently used on the farm.

First service pregnancy rates following post-AI use of HCG in Ovsynch and Heatsynch programmes in lactating dairy cows

Lactating dairy cows (n = 667) at random stages of the oestrous cycle were assigned to either ovsynch (O, n = 228), heatsynch (H, n = 252) or control (C, n = 187) groups. Cows in O and H groups received 100 microg of GnRH agonist, i.m. (day 0) starting at 44 +/- 3 days in milk (DIM), and 500 microg of cloprostenol, i.m. (day 7). In O group, cows received 100 microg of GnRH (day 9) and were artificially inseminated without oestrus detection 16-20 h later. In H group, cows received 1 mg oestradiol benzoate (EB) i.m., 24 h after the cloprostenol injection and were artificially inseminated without oestrus detection 48-52 h after the EB injection. Cows in C group were inseminated at natural oestrus. On the day of artificial insemination (AI), cows in all groups were assigned to subgroups as follows: human Chorionic Gonadotrophin (O-hCG) (n = 112), O-saline (n = 116), H-hCG (n = 123), H-saline (n = 129), C-hCG (n = 94) and C-saline (n = 93) subgroups. Cows in hCG and saline subgroups received 3000 IU hCG i.m. and or 10 ml saline at day 5 post-AI (day 15), respectively. Pregnancy status was assessed by palpation per rectum at days 40 to 45 after AI. The logistic regression model using just main effects of season (summer and winter), parity (primiparous and pluriparous), method(1) (O, H and C) and method(2) (hCG and saline) showed that all factors, except method(1), were significant. Significant effects of season (p < 0.01), hCG and parity (p < 0.01), and a trend of parity and season (p < 0.1) were detected. A clear negative effect of warm period on first service pregnancy rate was noted (p < 0.01). The pregnancy rate was the lowest in the H protocol during warm period (p < 0.05). Treatment with hCG 5 days after AI significantly improved pregnancy rates in those cows that were treated with the H protocol compared with saline treatments (41.5% vs 24.8%; p < 0.01). O and H were more effective in primiparous than in pluriparous cows (46.1% vs 29.9%; p < 0.1 and 43.6% vs 24.6%; p < 0.01). First service pregnancy rates were higher in primiparous hCG-treated than in pluriparous hCG-treated cows (57.9% vs 32.3%; p < 0.01). The pregnancy rate was higher for the hCG-treated cows compared with saline-treated cows during warm period (37.9% vs 23.6%; p < 0.001).

Differential alterations in the ability of bovine neutrophils to generate extracellular and intracellular reactive oxygen species during the periparturient period

The periparturient period of a dairy cow is associated with increased incidence and/or severity of certain infectious diseases, including mastitis. It is believed that the heightened physiological demands of calving and initiation of milk production contribute to a state of immunosuppression during this period. Previous studies have indicated that neutrophil production of reactive oxygen species (ROS), which is a critical element of the host innate immune response to bacterial infection, is impaired in the 1-2week period following calving. However, whether there is comprehensive inhibition of ROS production or selective inhibition of particular ROS remains unknown. The present study provides evidence that neutrophils isolated from cows (n=20) after calving have an increased capacity to generate intracellular ROS and an impaired ability to release extracellular superoxide anion and hydrogen peroxide.

Effect of restricting silage feeding prepartum on time of calving, dystocia and stillbirth in Holstein-Friesian cows

A study was carried out to investigate the effect of restricting silage feeding on time of calving and calving performance in Holstein-Friesian cows. In the treatment group (n = 1,248 cows, 12 herds) silage feeding commenced in the evening (17:00 to 20:00 h), after a period of restricted access (2 to 10 h) while in the control group ad-libitum access to silage was provided over the 24 h period (n = 1,193 cows, 12 herds). Daytime and nighttime calvings were defined as calvings occurring between the hours of 06:30 and 00:29 and between 00:30 and 06:29, respectively. Restricting access to silage resulted in less calvings at night compared to cows with ad-libitum access to silage (18 vs 22%, P < 0.05). Cows with restricted access to silage had a higher percentage of difficult calvings (11 vs 7%, P < 0.001) and stillbirths (7 vs 5%, P < 0.05) compared to cows in the control group. The percentage of calvings at night was lower (13%) when access to silage was restricted for 10 h compared to 2, 4 or 6 h (22, 18, 25%, respectively) (P < 0.001). Calf sire breed, calf gender or cow parity did not influence time of calving. In conclusion, offering silage to pregnant Holstein-Friesian cows in the evening, after a period of restricted access, reduced the incidence of nighttime calvings, but increased the incidence of dystocia and stillbirth.

Effect of Stillbirths on Dam Survival and Reproduction Performance in Holstein Dairy Cows

The objectives of this study were to evaluate the effect of stillbirth on survival and reproductive performance of lactating dairy cows. Data were collected from 2 different regions of the US calving-ease scores (CES) were recorded by farm personnel on a scale of 1 (no problem) to 5 (extreme difficulty). Stillbirths were recorded by farm personnel. The final analysis included 13,608 calvings of which 93.4% were live calves and 6.6% stillbirths. An increasing or decreasing trend in the incidence of stillbirth by parity and by CES was analyzed by Cochran-Armitage trend tests. A significant decreasing trend in the incidence of stillbirth by parity group was detected. The incidence of stillbirth increased as the CES increased. The incidence of stillbirths was 3.6, 11.2, 25.9, and 60.1% for CES score 1, 2, 3, and 4, respectively. Dam survival in the herd and reproductive performance were analyzed by the Cox proportional hazards model. Variables that decreased dam survival time were stillbirths, primiparity, and CES of 3 and 4. The variables that reduced reproductive performance were stillbirths, multiparity, male calves, and CES of 3 and 4. Cows that had stillbirths had significantly increased risk of culling/death throughout the lactation and increased median days open by 88 d compared with cows that had live calves. In conclusion, losses from stillbirths are far greater than just the value of the calf.

Milking Frequency, Estradiol Cypionate, and Somatotropin Influence Lactation and Reproduction in Dairy Cows

Our objectives were to determine lactational and reproductive outcomes in response to increased milking frequency (MF), injection of estradiol cypionate (ECP), and treatment with bovine somatotropin (bST). Lactating dairy cows (n = 144) were blocked by lactation number (1 vs. 2+) and assigned randomly to a 2 x 2 x 2 factorial experiment consisting of 8 treatment combinations: 1) MF consisting of 4x daily milking (4x) for the first 30 d in milk (DIM) vs. 2x daily milking (2x), with all cows milked 2x after 30 DIM; 2) 10 mg of ECP given postpartum at 8 +/- 3 DIM versus controls that received ECP diluent (oil); and 3) biweekly bovine somatotropin (bST), starting sometime after 60 DIM, versus no bST. Ovulation before the first artificial insemination was synchronized by using Heatsynch (GnRH injection 7 d before PGF2alpha followed in 24 h by ECP), and cows were artificially inseminated after detected estrus or at 48 h after ECP, whichever came first. Pregnancy was assessed by transrectal ultrasonography 28 to 30 d after artificial insemination. Daily yield and weekly components of milk were measured during the first 90 DIM. Intervals to first and second postpartum ovulation were unaffected by treatment, but cows were in estrus earlier after 2x (24 +/- 4 d) than 4x (41 +/- 4 d) daily MF, and sooner after ECP (25 +/- 3 d) than after oil (39 +/- 4 d) treatment. Pregnancy rates among 4x cows increased for ECP versus oil (52.8 vs. 27.8%) more than for cows with 2x MF treated with ECP versus oil (50.0 vs. 39.4%). Increased MF increased daily milk yields and energy-corrected milk yields during the first 30 DIM. Although milk yields were increased acutely by ECP during the 10 d after its injection, subsequent milk yields were decreased for ECP-treated cows previously milked 4x daily. Treatment with bST increased overall daily milk yields most in cows previously milked 2x daily and treated with oil and those milked 4x daily and treated with ECP. We concluded that early postpartum ECP injection increased pregnancy rates, but generally had detrimental effects on milk yields after 30 DIM for ECP-treated cows previously milked 4x daily, unless those cows also were treated with bST.

The effect of a monensin controlled-release capsule on the incidence of retained fetal membranes, milk yield and reproductive responses in Holstein cows

The objective of this study was to determine the effect of a monensin controlled-release capsule on the incidence of retained fetal membranes (RFM), milk yield and conception rate at first service (CRFS). The study was conducted during May to August 2004 in a large dairy herd in Chihuahua, Mexico. Cows (n = 2,025) from 20 to 30 d before expected parturition were randomly assigned to either a treatment or a control group. The treated group (n = 1,010) received orally a capsule of monensin that released 335 mg/d for 95 d. Control cows (no capsule, n = 1,015) were randomly assigned and matched by parity. Outcome variables were the incidence of RFM, first three test day milk and CRFS. Monensin decreased the incidence of RFM by 3.9% only in multiparous cows. Therefore, multiparous cows treated with monensin were 0.78 times (95% C.I. = 0.71-0.86) as likely as control multiparous cows to develop RFM. Overall, milk yield was negatively affected by the RFM condition, but it was improved by monensin only in multiparous cows with RFM at test day 1. Conception rate at first service was depressed by 10.6% in multiparous cows with RFM. However, in RFM cows treated with monensin, CRFS improved to the level of treated cows without RFM.

Effect of presence of clinical and subclinical endometritis at the initiation of Presynch-Ovsynch program on the first service pregnancy in dairy cows

The present study examined the effect of presence of clinical or subclinical endometritis at the initiation of Presynch-Ovsynch estrous synchronization program on the first service pregnancy rate in dairy cows. Lactating Holstein cows (N=275) were given a thorough reproductive examination at 32-38 days in milk, 3 days prior to the scheduled start of Presynch-Ovsynch program. Based on the reproductive exam findings the cows were diagnosed and classified into three groups as clinical endometritis, subclinical endometritis and normal. All cows received two set-up injections of 25mg PGF(2alpha) (Lutalyse((R)), Pfizer Animal Health, New York, NY, USA) i.m., 14 days apart starting at 35-42 days in milk (DIM). All cows received 75microg of GnRH (Cystorelin, Merial, Iselin, NJ, USA) i.m. 14 days after the second pre-synchronization injection of PGF(2alpha), followed by a third injection of 25mg PGF(2alpha) i.m. 7 days later. Cows received a second injection of 75microg of GnRH i.m. 54h after the third PGF(2alpha), and received timed artificial insemination at the time of the second GnRH injection or 24h later. Multivariate logistic regression was used to analyze the odds of pregnancy at the first service. Variables included in the model were endometritis status (clinical endometritis, subclinical endometritis and normal), farm (two), presence of corpus luteum (CL, yes or no), timing of second GnRH in relation to AI (0 or 24h), sire fertility (bulls with greater compared with lesser estimated relative conception rates), parity (primiparous and multiparous) and their interactions. Of all variable included in the model, cows with corpus letuem (OR=1.83 versus OR=1.00; P=0.05) 3 days prior to the scheduled start of Presynch-Ovsynch program and primiparous cows (OR=1.00 versus OR=0.55; P=0.04) had increased odds of becoming pregnant at the first service. No differences were found in the odds of first service pregnancy among clinical, subclinical endometritis and normal cows (P>0.1). In summary, presence of clinical or subclinical endometritis at the initiation of Presynch-Ovsynch estrous synchronization program does not harm the first service pregnancy rate in dairy cows.

Treatment of chronic endometritis in dairy cows with an intrauterine application of enzymes. A field trial

The use of proteolytic enzymes has been established in the non-antibiotic treatment of mastitis in dairy cattle. The objective of this study was to evaluate, if enzymes are efficacious in the treatment of chronic endometritis. In a controlled field trial, cows with vaginal discharge 21-27 days in milk (DIM) were randomly assigned to two treatment groups. Endometritis was classified into three categories, depending on the type of vaginal discharge: clear mucus with flakes of pus (E1), mucopurulent discharge or fluctuating contents in the uterus (E2), and purulent discharge (E3). In group ENZYMES (n=191), cows received an intrauterine treatment with a salve containing the enzymes trypsin (16 mg), chymotrypsin (16 mg), and papain (8 mg). Cows in group PGF (n=225) were treated with 0.5mg of cloprostenol. Cows that did not show any clinical signs of chronic endometritis were regarded as healthy control group (HC, n=699). In groups ENZYMES and PGF, all cows were re-examined 35-41 DIM. In group ENZYMES, cows were re-treated with enzymes if signs of endometritis were found, while in group PGF all cows received a second dose of cloprostenol, regardless of their clinical findings. Cure rate after the first treatment, defined as the absence of vaginal discharge at the re-examinations, was 59.7 and 68.0% in groups ENZYMES and PGF, respectively (P>0.05). Reproductive performance measures showed no significant differences between the two treatment groups. Service rate was significantly lower for ENZYMES and PGF, respectively, compared to HC. Conception rates to all services and percentages of cows pregnant by 250 DIM were significantly lower in group ENZYMES compared to HC, while no further differences were found between PGF and HC. In both treatment groups, cure rate and reproductive performance measures were better for cows categorized E1 or E2, than for cows categorized E3, respectively. Conception rate to all services for cows with endometritis category E1 was higher in group PGF than in group ENZYMES (P<0.05). The results of this field trial suggest that prostaglandin F(2alpha) is still the treatment of choice for chronic endometritis in dairy cattle.

Inseminations at Estrus Induced by Presynchronization Before Application of Synchronized Estrus and Ovulation

A controlled field study examined conception rates after 2 timed artificial insemination (TAI) breeding protocols conducted on 2 commercial dairy farms. Estrous cycles in postpartum lactating cows were presynchronized with 2 injections of PGF(2alpha) given 14 d apart (Pre-synch) and then, after 12 d, the standard Ovsynch protocol (injection of GnRH 7 d before and 48 h after an injection of PGF(2alpha), with one TAI at 12 to 16 h after the second GnRH injection) or Heatsynch protocol [injection of GnRH 7 d before an injection of PGF(2alpha), followed 24 h later by 1 mg of estradiol cypionate (ECP) and one TAI 48 h after ECP] was applied. Experimental design allowed artificial insemination to occur anytime after the second Presynch injection and during the designed breeding week when estrus was detected. Of the 1846 first services performed, only 1503 (rate of compliance = 81.4%) were performed according to protocol. Numbers of cows inseminated, logistic-regression adjusted conception rates, and days in milk (DIM) were for inseminations made: 1) during 14 d after first Presynch injection (n = 145; 22.6%; 54 +/- 0.4 DIM); 2) during 12 d after second Presynch injection (n = 727; 33%; 59 +/- 0.2 DIM); 3) during 7 d after the first GnRH injection of Ovsynch or Heatsynch (n = 96; 32.1%; 74 +/- 0.5 DIM); 4) after estrus as part of Heatsynch (n = 212; 44.6%; 76 +/- 0.3 DIM); 4) after TAI as part of Heatsynch (n = 154; 21.1%; 76 +/- 0.4 DIM); 5) after estrus as part of Ovsynch (n = 43; 48.7%; 77 +/- 0.7 DIM); and 6) after TAI as part of Ovsynch (n = 271; 24.4%; 77 +/- 0.3 DIM). Conception rates when AI occurred after one Presynch injection were less than when AI occurred after 2 Presynch injections. Conception rates for those inseminated after either Presynch injection did not differ from those inseminated after combined Heatsynch + Ovsynch. Cows in the Ovsynch and Heatsynch protocols inseminated after estrus during the breeding week had greater conception rates than those receiving the TAI, but overall conception rates did not differ between protocols. Among cows inseminated after detected estrus, conception was greater for cows in the Heatsynch + Ovsynch protocol (77 +/- 0.4 DIM) than for those inseminated after either Presynch injection (54 +/- 0.4 or 59 +/- 0.2 DIM). We concluded that conception rates after Heatsynch and Ovsynch were similar under these experimental conditions, and that delaying first AI improved fertility for cows inseminated after detected estrus.

Efficacy of ceftiofur hydrochloride sterile suspension administered parenterally for the treatment of acute postpartum metritis in dairy cows

OBJECTIVE

To evaluate the efficacy of ceftiofur hydrochloride sterile suspension administered parenterally for treatment of acute postpartum metritis (APM) in dairy cows.

DESIGN

Multilocation, randomized block, field trial.

ANIMALS

406 cows in the first 14 days postpartum.

PROCEDURE

Cows with rectal temperatures > or = 39.5 degrees C (103.1 degrees F) without clinical signs of respiratory or gastrointestinal tract disease and with a fetid vaginal discharge were allocated randomly in blocks of 3 to 3 treatment groups: sterile saline (0.9% NaCl) solution administered at a dosage of 2 mL/45.4 kg (2 mL/100 lb), SC or IM, once daily for 5 days (control); or ceftiofur hydrochloride administered at a dosage of 1.1 or 2.2 mg of ceftiofur equivalents (CE)/kg (0.5 or 1 mg/lb, respectively), SC or IM, once daily for 5 days. Cows were evaluated on days 6, 10, and 14, and clinical cure or failure to cure was determined. Clinical cure was defined as no additional antimicrobial treatment administered, rectal temperature < 39.5 degrees C, and absence of a fetid vaginal discharge.

RESULTS

On day 14, clinical cure rates were 77%, 65%, and 62% for the 2.2 mg of CE/kg, 1.1 mg of CE/kg, and control groups, respectively. No significant differences were detected in clinical cure rates between control and treatment groups on day 10 or 6.

CONCLUSIONS AND CLINICAL RELEVANCE

Ceftiofur hydrochloride administered at a dosage of 2.2 mg of CE/kg, SC or IM, once daily for 5 days was efficacious for treatment of APM in dairy cows.

Use of Ovsynch in dairy herds—differences between primiparous and multiparous cows

Ovsynch protocols are used to increase service rate and decrease days open and cullings for infertility. Recent reports have indicated better results after Ovsynch in primiparous than in older cows. However, this was not observed in all investigations on the subject. The objective of the study was to evaluate differences between primiparous and multiparous cows after synchronization of ovulation with an Ovsynch protocol in six trials. A total of 1584 cows (583 primiparous and 1001 multiparous cows, respectively) on three dairy farms were synchronized with an Ovsynch protocol consisting of a GnRH-analogue at Days 0 and 9, and a prostaglandin F(2alpha) analogue on Day 7. AI was carried out in all cows 16-20 h after the last treatment. Cows were categorized into primiparous and multiparous cows for analysis. Conception rate (CR) to timed AI, to further AI, overall conception rate and proportion of cows pregnant by 200 days in milk were compared between the age groups. Finally, two logistic regression models were calculated with conception to first service and conception by 200 DIM as the outcome variables. Independent variables were trial (categorical) and age group (primiparous versus multiparous). Conception rates to TAI were higher in primiparous than in older cows (37.9% versus 31.6%, P=0.015). Likewise pregnancy rates by 200 DIM were higher in primiparous cows (81.8% versus 75.4%, P=0.003). However, the extent of the difference varied between trials. Results indicate that Ovsynch protocols are more effective in primiparous than in older cows.

Evaluation of effect of estradiol cypionate administered prophylactically to postparturient dairy cows at high risk for metritis

OBJECTIVE

To determine whether 4 mg of estradiol cypionate (ECP) administered prophylactically to high-risk postparturient dairy cows decreases incidence of postpartum metritis.

DESIGN

Randomized, placebo-controlled, triple-masked clinical trial.

ANIMALS

250 postparturient dairy cows in a herd with postparturient hypocalcemia, retained fetal membranes, dystocia, stillbirth, or twins.

PROCEDURE

Cows were given 4 mg of ECP (treatment) or 2 mL of vegetable oil (control) by i.m. injection within 24 to 36 hours of calving. Monitoring rectal temperatures and evaluation for metritis was performed once daily for 10 days. Cows with fever > or = 39.7 degrees C (103.5 degrees F) were treated with 1.5 g of ceftiofur hydrochloride.

RESULTS

When assessed by ordinal logistic regression, there were no differences between groups in incidence of mild or severe metritis. Cows that calved during the second or third quarter of the year were at increased risk of metritis, compared with those that calved during the fourth quarter. Following stratification by lactation (first and > or = 2), it was observed that multiparous cows that did not receive antimicrobials during the first 3 days of the postparturient period were 5 times as likely to have metritis, compared with cows treated with antimicrobials on the basis of fever or other concurrent disease.

CONCLUSIONS AND CLINICAL RELEVANCE

Prophylactic administration of ECP to dairy cows at high risk for metritis did not reduce risk for metritis. Treating multiparous cows with antimicrobials on the basis of fever during the early postpartum period was associated with decreased incidence of metritis.

The effect of treatment of clinical endometritis on reproductive performance in dairy cows

The objective of this field trial was to compare the effect of intrauterine (i.u.) antibiotic or intramuscular (i.m.) prostaglandin F2 alpha (PGF2 alpha) on time to pregnancy in dairy cows diagnosed with clinical endometritis between 20 and 33 days in milk (DIM). The case definition of endometritis was the presence of purulent uterine discharge or cervical diameter > 7.5 cm, or the presence of muco-purulent discharge after 26 DIM. There were 316 cows with endometritis from 27 farms assigned randomly within herd to receive 500 mg of cephapirin benzathine intrauterine (i.u.), 500 micrograms of cloprostenol i.m., or no treatment. The rate of resolution of clinical signs 14 d after treatment was 77% and was not affected by treatment. Reproductive performance was monitored for a minimum of 7 mo after treatment. Survival analysis (multivariable proportional hazards regression) was used to measure the effect of treatment on time to pregnancy. There was no benefit of treatment of endometritis before 4 wk postpartum. Administration of PGF2 alpha between 20 and 26 DIM to cows with endometritis that did not have a palpable corpus luteum was associated with a significant reduction in pregnancy rate. Between 27 and 33 DIM, cows with endometritis treated with cephapirin i.u. had a significantly shorter time to pregnancy than untreated cows (hazard ratio = 1.63). In this time period, there was no difference in pregnancy rate between PGF2 alpha and untreated cows, but the difference in pregnancy rate between cows treated with cephapirin i.u. and with PGF2 alpha was not statistically significant. Treatment of postpartum endometritis should be reserved for cases diagnosed after 26 DIM, based on criteria that are associated with subsequent pregnancy rate.

Relevance of apolipoproteins in the development of fatty liver and fatty liver-related peripartum diseases in dairy cows

Most metabolic diseases in dairy cows occur during the peripartum period and are suggested to be derived from fatty liver initially developed during the nonlactating stage. Fatty liver is induced by hepatic uptake of nonesterified fatty acids that are released in excess by adipose tissues attributable to negative energy balance. The fatty accumulation leads to impairment of lipoprotein metabolism in the liver, and the impairment in turn influences other metabolic pathways in extrahepatic tissues such as the steroid hormone production by the corpus luteum. Detailed understanding of the impaired lipoprotein metabolism is crucial for elucidation of the mechanistic bases of the development of fatty liver and fatty liver-related peripartum diseases. This review summarizes results on evaluation of lipoprotein lipid and protein concentrations and enzyme activity in cows with fatty liver and those with ketosis, left displacement of the abomasum, milk fever, downer syndrome and retained placenta. Obtained data strongly suggest that decreases in serum concentrations of apolipoprotein B-100, apolipoprotein A-I and apolipoprotein C-III, a reduction in activity of lecithin:cholesterol acyltransferase and induction of haptoglobin and serum amyloid A are intimately related to the development of fatty liver and fatty liver-related diseases. Moreover, determination of the apolipoprotein concentrations and enzyme activity during the peripartum period is useful for early diagnoses of these diseases.

Pharmacokinetics of ceftiofur in plasma and uterine secretions and tissues after subcutaneous postpartum administration in lactating dairy cows

A study was conducted to measure concentrations of potentially active ceftiofur derivatives, in plasma, in uterine tissues (endometrium and caruncles) and in uterine secretions at different time points after a single subcutaneous administration of ceftiofur hydrochloride (Excenel RTU Sterile Suspension) at the dose of 1 mg/kg body weight in Holstein-Friesian dairy cows. The animals (n=4) were injected within 24 h of calving, after expulsion of the foetal membranes. Plasma, lochial fluid, caruncles and endometrium were collected before ceftiofur hydrochloride administration and at 1, 2, 4, 8, 12 and 24 h after treatment. For each cow the concentrations of ceftiofur in the biological matrices were quantified using an high-performance liquid chromatography (HPLC) assay. The limit of quantification of the method was 0.1 microg/mL for plasma and 0.1 microg/g for lochial fluid, caruncles and endometrium. The concentrations of potentially active ceftiofur derivatives detected in plasma reached a maximum of 2.85 +/- 1.11 microg/mL at 2 h and decreased to 0.64 +/- 0.14 microg/mL at 24 h after administration. In lochial fluid, these concentrations reached a maximum of 0.97 +/- 0.25 microg/g at 4 h and decreased to 0.22 +/- 0.21 microg/g at 24 h after administration. In endometrium, these concentrations reached a maximum of 2.23 +/- 0.82 microg/g at 4 h and decreased to 0.56 +/- 0.14 microg/g at 24 h following the injection, whereas these levels in caruncles were 0.96 +/- 0.45 and 0.60 +/- 0.39 microg/g obtained at 8 and 24 h, respectively. At the dose of 1 mg/kg body weight in healthy dairy cows, subcutaneous administration of ceftiofur (as ceftiofur hydrochloride) after parturition results in concentrations of ceftiofur derivatives in uterine tissues and in lochial fluid that exceed the reported minimal inhibitory concentrations (MICs) for the common pathogens (Escherichia coli, Fusobacterium necrophorum, Bacteroides spp., and Arcanobacterium pyogenes) associated with acute puerperal metritis.

Multilocation trial of ceftiofur for treatment of postpartum cows with fever

OBJECTIVE

To evaluate the effect of ceftiofur for treatment of postpartum cows with fever.

DESIGN

Multilocation randomized complete block design trial.

ANIMALS

330 cows.

PROCEDURE

Cows with rectal temperature > or = 39.5 C (103.1 F) during the first 10 postpartum days were randomly assigned to a treatment (ceftiofur; 1 mg/kg [0.45 mg/lb] of body weight daily for 3 days) or untreated control group. Cure (no additional or alternative antimicrobial treatment used, rectal temperature < 39.5 C, and no other concurrent clinical signs of disease when evaluated at 9 or 10 days after enrollment), milk production, and rectal temperature were evaluated.

RESULTS

Ceftiofur-treated cows were significantly more likely to be cured than control cows (56.0 vs 28.9%, respectively), with an odds ratio of 3.14 when vaginal discharge (a factor with moderate interaction with treatment) was present at enrollment. Among cows that had an abnormal calving (a significant interaction factor), treated cows had first milking yield 2.27 kg (5 lb) greater than control cows. Treated cows had a significantly greater reduction in rectal temperature (1.19 C [2.14 Fl), compared with control cows (1.04 C [1.87 F]).

CONCLUSIONS AND CLINICAL RELEVANCE

Parenteral administration of ceftiofur significantly improved cure rate, milk yield, and rectal temperature in postpartum cows with fever and vaginal discharge or dystocia. These findings provide information to determine appropriate treatment for postpartum cows, which for years has been debated in the dairy industry.

Relationships between fatty liver and fertility and some periparturient diseases in commercial Dutch dairy herds

Declining fertility in dairy cows is frequently suggested to arise from the occurrence of a more negative energy balance and/or the concomitant increased accumulation of triacylglycerol in the liver. Therefore, we performed a field study to assess the clinical effects of postpartum fatty liver in dairy cows on fertility and reproductive disease. Data were collected from 360 cows from nine dairy herds on fertility, diseases, and the liver triacylglycerol content on two occasions during lactation: 6 to 17 days and 38 to 50 days postpartum. The mean concentration of triacylglycerol in the liver was 54.6 mg/g from 6 to 17 days and 38.4 mg/g from 38 to 50 days postpartum. The probability of pregnancy was 30% lower for cows with higher contents of triacylglycerol in the liver compared to the probability for cows with low liver triacylglycerol (P = 0.049). The probability of estrus was also 35% lower for the cows with high triacylglycerol in the liver. This resulted in larger intervals between parturition and first heat and parturition and pregnancy for these cows. There was no effect observed on the first insemination conception rate. Given a certain level of triacylglycerol, recorded milk production had a positive effect on time to pregnancy. The incidences of endometritis, lochiometra and cystic ovarian follicles were not higher in cows with higher liver triacylglycerol contents. Endometritis was associated with a lower first insemination conception rate and more days open (chi2 = 4.26, P = 0.03 and T-test = -2.02, P= 0.04 respectively). We concluded that our results support the idea that differences in the negative energy balance or the accumulation of triacylglycerol in the liver of postpartum dairy cows affect fertility performance. The data also indicate that an increase in milk production has no negative impact on fertility as long as the amount of triacylglycerol in the liver remains the same.

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

Effects on reproduction of dystocia, stillbirth, abortion, milk fever, retained placenta, metritis, cystic ovaries, anestrus, ketosis, displaced abomasum, locomotor disorders, and mastitis were reviewed. Papers were considered if they provided quantitative estimates of diseases on days to first estrus, days to first service, conception rate at first service, days from first service to conception, days to conception or days open, calving interval, conception rates at various days post partum (dpp), and number of services per conception or per cow. Only papers in English in peer-reviewed journals were selected for analysis of post 1960 data from intensive dairy regions. Seventy papers fulfilled the selection criteria. Summary estimates of disease effects were calculated according to meta-analysis methods, and study designs were described in detail to identify possible heterogeneity of the results. Stillbirth, milk fever, displaced abomasum and mastitis had no effect on reproduction. Clinical ketosis, dystocia and retained placenta were associated with 2 to 3 more days to first service and with a 4 to 10% lower conception rate at first service, resulting in 6 to 12 more days to conception. Locomotor disorders were associated with an average increase of 12 d to conception, with wide variation depending on lesions and stage of occurrence. Metritis was associated with 7 more days to first service, 20% lower conception rate at first service, resulting in 19 more days to conception. Cystic ovaries were associated with 6 to 11 more days to first service and with 20 to 30 more days to conception. Anestrus was associated with 26 more days to first service and with an 18% lower conception rate at first service, resulting in 41 more days to conception. Abortion was associated with 70 to 80 more days to conception.

Risk factors for stillbirth in Holstein heifers under field conditions in France: a prospective survey

Risk factors for stillbirth, defined as birth of a dead calf or a calf dead within 24 h after parturition, were studied in Holstein heifers. Data came from an overall 4-yr prospective survey conducted in French dairy herds. Only heifers that delivered a single calf were included in the study. The stillbirth incidence was 6.9%. The predictive indicators of stillbirth risk were: gestation length, prepartum body condition and dirtiness scores, biochemical and hematological blood parameters measured during the last 2 mo of gestation, and calving conditions. Multiple logistic regressions were run using herd, calving year, calving season, blood sampling-to-parturition interval, and body scoring-to-parturition interval as the fixed effects. The results, expressed as the ratio of the odds of disease occurrence in the exposed and non-exposed subgroups (OR), indicated that dystocia and a body condition score (BCS) higher than 4 before calving were significant risk factors for stillbirth (OR=14.6, P<0.0001 and OR=2.98, P<0.05, respectively). Prepartum circulating neutrophil counts higher than 1950/mm3 (OR=0.50, P<0.05) were associated with a lower risk of stillbirth. A higher occurrence of placental retention, lower fertility and a lower 305-d milk yield were significant consequences of stillbirth.

A review of the feeding-health-production complex in a dairy herd

Diseases may be an important link in the relationship between feeding and production in a dairy herd. The low frequency of relevant disorders calls for studies on survey data on a large population. However, this approach suffers from lack of detailed herd feeding data and consequently only few have studied feeding as a risk factor for disease. Therefore, we reviewed information from various studies to integrate what is known of the feeding-health-production complex in a dairy herd. The need for putting together information from different sources, the herd effects, and the fact that the effect of one factor cannot be kept constant for investigation in a real-life dynamic herd call for a conceptual model as a framework for the review. The complexity is minimized to allow the representation of important elements. Within-cow relationships (such as feeding-disease relationships, disease interrelationships, and disease-production relationships) are reviewed specifically for: ketosis, milk fever, displaced abomasum, acidosis, sole ulcers and laminitis, and bloat. The major feeding management factors involved are concentrate feeding (level and how it is provided) and overconditioned cows. Disease interrelationships are important. Generalization of production loss from diseases is complicated due to the variety of estimates and measures used.