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Mycoplasma wenyonii (fmr. Eperythrozoon wenyonii) is a hemotrophic, epicellular bacterial parasite of cattle and is associated with clinical disorders including hemolytic anemia, decreased milk yield, and scrotal, teat, and hindlimb edema. M. wenyonii and related organism, Candidatus Mycoplasma haemobos have been found in apparently healthy cattle in other countries, but little is known about their prevalence in the U.S. The objective of this prospective, cross-sectional study was to determine herd-level prevalence of M. wenyonii and C.M. haemobos in dairy cattle located in WI and MI., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2019

The dairy industry is relying more on hired labor to milk cows and many dairy operations are increasing pressure on employees to maintain high levels of milking parlor throughput. This management emphasis negatively impacts milking protocols that are aligned with milk quality. Parlor efficiency is often defined in terms of cows milked per hour. However, we need to consider milking efficiency to include milk quality, milk flow, and employee performance (Moore-Foster et al., 2019; Erskine et al., 2019). The purpose of this study was to determine the impact of poor pre-milking preparation (as evidenced by bi-modal milk letdown) on subsequent milk production. Erskine, RJ, B Norby, LM Neuder, et al. 2019. Decreased milk yield is associated with delayed milk ejection. J. Dairy Sci. (in press) Moore-Foster R, B Norby, RL Schewe, et al. 2019. Herd-level variables associated with delayed milk ejection in Michigan dairy herds. J. Dairy Sci. 102:696-705., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2019

Bovine leukemia virus is a deltaretrovirus of cattle and the causitive agent of enzootic bovine leukosis. A small proportion of infected animals develop the clinical manifestation of lymphoma, however the majority remain subclinically infected. Infection is common in the U.S. dairy cattle population and in other major dairy producing countries that have not taken steps to reduce and erradicate infection in their populations. The 1997 and 2008 NAHMS dairy studies examined the prevalence of BLV infection at the cow and herd levels, respectively. There has been no updated estimates of prevalence in the U.S. cattle population in the last decade. Within that time, evidence of the negative impact of subclinical infection has been mounting. Cows exhibit alterations in immune function, decreased longevity, and reduced milk production. The first major objective of this study was to provide an updated estimate of BLV prevalence in a multistate sample of U.S. dairy cattle. The second major objective was to measure herd and cow level associations between BLV prevalence and economically important dairy production outcomes, namely milk production, reproductive efficiency, and somatic cell count., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2019

Bovine Tuberculosis (BTB) is an endemic disease in about one hundred countries, affecting the economy causing a decrease in productivity, condemnation of meat, and damaging the credibility on international trade. Additionally, Mycobacterium bovis the major causative agent for BTB can also infect humans causing a variety of clinical presentations. The aim of this study was to determine BTB prevalence and the main risk factors for theMycobacterium bovis prevalence in cattle and buffalos in Amazonas State, Brazil. Tissue samples from 151 animals (45 buffalo and 106 cattle from five herds with buffalo only, 22 herds with cattle only, and 12 herds with buffalo and cattle) were obtained from slaughterhouses under State Veterinary Inspection. M. bovis were isolated on Stonebrink medium. The positive cultures were confirmed by polymerase chain reaction (PCR) testing. The apparent herd and animal prevalence rates were 56.4 and 5.40%, respectively. Regarding animal species, the apparent prevalence rates were 3% in cattle and 11.8% in buffalo. Generalized Linear Mixed Models (GLMM) with random effect were used to assess the association with risk factors on the prevalence. Species (buffalo), herds size (>100 animals) and the presence of both species (buffalo and cattle) in the herd were the major risk factors for the infection by Mycobacterium bovis in the region. The findings reveal an urgent need for evidence-based effective intervention to reduce BTB prevalence in cattle and buffalo and prevent its spread to the human population. Studies are needed to understand why buffalo are more likely to be infected by M. bovis than cattle in Amazon. Recommendations for zoning, use of data from the inspection services to generate information regarding BTB focus, adoption of epidemiological tools, and discouragement of practices that promote the mixing of cattle and buffalo, were made. Made available in DSpace on 2019-12-31T00:39:03Z (GMT). No. of bitstreams: 1 EpidemiologicalStudyofMycobacteriumbovisInfection.pdf: 195869 bytes, checksum: 06f8d2918c89a9252c81ed8539e5f4ca (MD5) Previous issue date: 2019

Bovine leukosis is a chronic lymphoproliferative disorder in cattle caused by the deltaretrovirus, bovine leukemia virus (BLV). Most BLV infected animals remain asymptomatic and act as carriers of the virus; 30 to 40% of infected cattle develop a persistent lymphocytosis, while less than 5% progress to lymphosarcoma. The major route of virus transmission is believed to be iatrogenic through procedures that permit the transfer of blood between cattle. Proviral DNA has been identified in nasal secretions, saliva, semen, and smegma. Natural transmission through these secretions has not been clearly demonstrated. Our research group has identified the use of bulls in dairy herds as a risk factor for BLV infection at the herd level, and has also shown a high prevalence ( 45%) of infected beef bulls in Michigan. Natural service is still used in half of dairy operations across the US, and is the most commonly used breeding method (approximately 90%) in beef cattle herds in the US. Given these factors, there may be risk of BLV transmission during natural breeding via smegma or blood transfer following trauma to the penis, vulva, and vagina. The overall goal of our research team is to develop cost effective strategies to reduce the transmission of BLV in cattle herds. The objective of this study is to assess the risk of BLV transmission by breeding bulls during natural breeding., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2018

Bovine leukemia virus (BLV) is a deltaretrovirus prevalent in approximately 80% of US dairy herds and 30% of US dairy cattle. Previous work by our research group and others has shown that BLV infection leads to decreased milk production, impaired immune response, and decreased longevity among positive dairy cattle. Much of this work was part of a 2010 study of 113 Michigan dairy herds. Our research group is currently undertaking a nationwide study of bovine leukemia virus, in which we will be enrolling 120 herds from 11 states. The objective of this study is to confirm our findings from Michigan on a broader national scope. The descriptive epidemiology of bovine leukemia virus among herds enrolled in this study are presented here., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2015

Bovine leukemia virus (BLV) is a contagious retrovirus of cattle. Little is known about the prevalence, risk factors, or potential health impacts of BLV in beef cattle. Most cattle remain asymptomatic, but 30 to 40% will develop persistent leukocytosis. Fewer than 5% of infected cattle develop malignant lymphosarcoma, which in the US, is the most common neoplastic disease of cattle discovered at slaughter. Recent studies have suggested that BLV prevalence has increased dramatically, and has a previously unappreciated economic impact on the cattle industry. The objectives of this study were to determine the crude and age-specific prevalence of BLV among beef bulls in Michigan, assess the possible impact of BLV infection on bull fertility, and identify the major risk factors for BLV transmission among beef bulls., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2013

Rapid assays for on-farm detection of antimicrobial residues in milk collected from individual cows would be advantageous to reduce risks of violative residues in marketed milk. The objective of this project was to evaluate the accuracy of a rapid immunomigration assay (BetaStar® Plus, N eogen Corporation, Lansing, MI) for detecting β-lactam antibiotic residues in milk collected from individual dairy cows treated for mastitis. This assay is currently FDA-approved for detecting β-lactam antibiotic residues in commingled milk., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2013

Antimicrobial resistance is a growing concern in both food animal and public health. However, the role of antimicrobial use and management practices used on livestock operations on the accumulation, dissemination, and persistence of resistance has not been clearly determined. Most studies on antimicrobial resistance were conducted as cross-sectional observational studies; therefore, little is known about the dynamics of antimicrobial resistance in an animal as it transitions through various production phases or the impact of antimicrobial treatments on resistance over time. The goals of this study were to determine temporal changes in the quantities of susceptible and resistant coliform bacteria to four antimicrobials in fecal samples that were collected throughout a full production cycle, and to determine whether health or performance events affect the quantity or patterns of antimicrobial-resistant bacteria in dairy cattle., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2012

Bovine tuberculosis skin tests have been used successfully for control and eradication of bovine tuberculosis in the United States since the eradication program was begun in 1917. In 1992, there were only 10 states that had not achieved tuberculosis-free status. Unfortunately, bovine tuberculosis has become endemic in the cattle population in certain areas in the United States, including the northern part of the Michigan's Lower Peninsula. The caudal fold test is a key element of herd-level and individual animal screening. The specificity of the caudal fold tuberculin test is not perfect, and has been estimated to be approximately 89-96%. It is also evident that the specificity of the caudal fold tuberculin test is not a constant in different cattle populations. Variation in specificity may be due to differences in the amount and concentration of the tuberculin used for the test, regional variation in cross-reacting mycobacteria that cause false-positive results on the caudal fold tuberculin test, and variation in the interpretation of the test results by the testing veterinarians. The objective of this study was to use available data from the bovine tuberculosis testing program in Michigan to evaluate possible associations between the proportion of false-positive results on the caudal fold tuberculin test, and factors regarding geography and type of herd., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2005