In this prospective cohort study, Holstein cows considered to be at high risk of developing metritis (dystocia, twins, stillbirth, retained placenta, or their combination) were matched with herdmates at low risk of developing metritis (normal calving) and monitored daily for rectal temperature and uterine discharge during the first 12 d in milk (DIM). Blood was sampled on d 0, 1, and 3 postpartum for assessment of neutrophil phagocytic and oxidative burst activities. Blood was also sampled at 0, 1, 2, 3, 4, 7, and 12 DIM for determination of serum concentrations of Ca, K, Mg, nonesterified fatty acids, β-hydroxybutyrate, and glucose. On the basis of receiver operator characteristic curves, subclinical hypocalcemia (SCH) was defined as a serum Ca concentration ≤8.59 mg/dL in at least 1 sample in the first 3 DIM. The overall incidences of metritis and puerperal metritis were 47.3 and 30%, respectively. Concentration in blood and percentages of neutrophils undergoing phagocytosis and oxidative burst were all reduced in cows with SCH compared with normocalcemic cows. Cows with SCH were at a greater risk of developing fever, metritis, and puerperal metritis compared with normocalcemic cows. Among cows at low risk of developing metritis, those with SCH had a greater incidence of metritis (40.7%) compared with normocalcemic cows (14.3%). Similarly, among cows at high risk of developing metritis, cows with SCH had a greater incidence of metritis (77.8%) compared with normocalcemic cows (20.0%). Cows with SCH had elevated concentrations of nonesterified fatty acids and β-hydroxybutyrate compared with normocalcemic cows. The relative risk of developing metritis decreased by 22% for every 1mg/dL increase in serum Ca. Neither metritis nor SCH influenced the resumption of estrous cyclicity by 38 DIM, but cows with SCH had a reduced pregnancy rate and a longer interval to pregnancy compared with normocalcemic cows. Finally, the population risk to develop uterine diseases attributable to SCH was 66.6% for metritis and 91.3% for puerperal metritis in the present study.

Consensus Statements of the American College of Veterinary Internal Medicine (ACVIM) provide the veterinary community with up-to-date information on the pathophysiology, diagnosis, and treatment of clinically important animal diseases. The ACVIM Board of Regents oversees selection of relevant topics, identification of panel members with the expertise to draft the statements, and other aspects of assuring the integrity of the process. The statements are derived from evidence-based medicine whenever possible and the panel offers interpretive comments when such evidence is inadequate or contradictory. A draft is prepared by the panel, followed by solicitation of input by the ACVIM membership which may be incorporated into the statement. It is then submitted to the Journal of Veterinary Internal Medicine, where it is edited prior to publication. The authors are solely responsible for the content of the statements. Mycoplasma bovis is a pathogen causing respiratory disease, otitis media, arthritis, mastitis, and a variety of other diseases in cattle worldwide. It is increasingly recognized by the veterinary and livestock communities as having an important impact on the health, welfare, and productivity of dairy and beef cattle. M. bovis diseases can be difficult to diagnose and control because of inconsistent disease expression and response to treatments and vaccines, and large gaps in our understanding of the epidemiology and pathophysiology of these diseases. There are limited data on which to base evidence-based decisions for treatment and control, and the literature contains differing clinical biases and opinions. This document is intended for veterinarians dealing with cattle and is focused on the cattle production systems of North America. The goal of the consensus statement panel was to encourage an evidence-based approach to M. bovis problems. The scientific literature was critically reviewed, including peer-reviewed journal articles and reviews obtained by database searches using the terms ''Mycoplasma bovis'' or ''mycoplasma 1 cattle.'' Where other data were lacking, conference proceedings were reviewed as a source of expert opinion. Mycoplasma bovis Infections in Cattle

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The objectives of this study were to identify factors associated with colostral specific gravity in dairy cows, as measured by a commercially available hydrometer (Colostrometer). Colostral specific gravity was measured in 1085 first-milking colostrum samples from 608 dairy cows of four breeds on a single farm during a 5-yr period. Effects of breed, lactation number, and month and year of calving on colostral specific gravity were determined, as were correlations between colostral specific gravity, nonlactating period length, and 305-d yields of milk, protein, and fat. For 75 multiparous Holstein cows, relationships between colostral specific gravity, colostral IgG1, protein, and fat concentrations, and season of calving were determined. Colostral specific gravity values were lower for Brown Swiss and Ayrshire cows than for Jersey and Holstein cows, and lower for cows entering first or second lactation than third or later lactations. Month of calving markedly affected colostral specific gravity values, with highest values occurring in autumn and lowest values in summer. In multiparous Holstein cows, colostral specific gravity was more strongly correlated with colostral protein concentration (r = 0.76) than IgG1 concentration (r = 0.53), and colostral protein concentration varied seasonally (higher in autumn than summer). Our results demonstrate that colostral specific gravity more closely reflects colostral protein concentration than IgG1 concentration and is markedly influenced by month of calving. These results highlight potential limitations of using colostral specific gravity as an indicator of IgG1 concentration.

The effects of mastitis during the late nonlactating period on colostral volume and concentrations and total yields of immunoglobulin (Ig) G1, fat, and protein in colostrum were investigated using matched pairs of mammary glands from multiparous Holstein cows. Samples of mammary secretions were collected at approximately 14 and 7 d prepartum and within 3 h after calving. At each sampling time, the glands and secretions were examined for gross abnormalities, and the California Mastitis Test was performed. Duplicate secretion samples from each gland were cultured, and somatic cell count, pH, and fat and protein concentrations were determined. The volume of colostrum obtained at the first milking of each gland was quantified using a quarter milking device, and its IgG1 concentration was measured. Colostral volume from persistently infected mammary glands was lower than that from matched uninfected glands, as was the total mass of IgG1. However, infection did not alter IgG1 concentration in colostrum. Fat and protein percentages were lower in prepartum secretions but not in colostrum from infected glands. Persistent infection was associated with increased somatic cell count and pH of secretions at all sampling times, and California Mastitis Test scores were higher for colostrum from infected glands. The appearance of secretions was extremely variable, but the presence of flakes or clots in colostrum was associated with infection. We concluded that mastitis during the late nonlactating period alters mammary gland function but is unlikely to be an important contributor to the high rate of failure of passive transfer of immunoglobulins in calves.