John Maas

The correlation between serum selenium and blood selenium in cattle.

The selenium (Se) concentration of paired blood and serum samples from cattle was determined by 2 methods: 1) atomic absorption spectroscopy using hydride generation (HG-AAS), and 2) inductively coupled argon plasma emission spectroscopy using hydride generation (ICP). Samples from 327 cattle were analyzed by HG-AAS, and samples from 344 cattle were analyzed by ICP. The data were examined by linear regression analysis, and the technique of inverse prediction was utilized to determine prediction intervals for estimating blood Se concentration from known serum Se concentration. The correlation coefficients, by simple linear regression of serum Se on blood Se, were 0.79 (r 2 = 0.62) and 0.88 (r 2 = 0.77) for the HG-AAS data and the ICP data, respectively. For the HG-AAS data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was For the ICP data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was The prediction intervals were quite wide, and the accuracy of estimating blood Se from a known serum Se was not useful for diagnostic purposes. The use of serum Se concentration to assess nutritional status of cattle with respect to Se does not appear to be appropriate.

Molecular identification of a novel deltaproteobacterium as the etiologic agent of epizootic bovine abortion (foothill abortion)

ABSTRACT Epizootic bovine abortion (EBA) is endemic in Californias coastal range and the foothill regions of the Sierra Nevada, where it has been the primary diagnosed cause of abortion in beef cattle for >50 years. Investigation of these losses has defined a specific fetal syndrome characterized by late-term abortion or birth of weak or dead calves. Although the unusual clinical presentation and unique fetal pathology associated with EBA have been recognized since the 1950s, the identity of the etiologic agent is unknown. In this study, suppression-hybridization PCR was used to identify a fragment of the 16S rRNA gene of a previously undescribed bacterium in thymus tissue derived from affected fetuses. Phylogenetic analysis revealed that this pathogen was a deltaproteobacterium closely related to members of the order Myxococcales. A specific PCR was subsequently developed to detect the presence of this bacterium in DNA extracted from fetal thymuses. Using histopathology as the definitive diagnosis for EBA, this PCR demonstrated 100% specificity and 88% sensitivity. The bacterium was also detected in the argasid tick Ornithodoros coriaceus, which is the recognized vector of EBA. These data imply a close association between this novel agent and the etiology of EBA.

Copper Toxicosis in Two Herds of Beef Calves following Injection with Copper Disodium Edetate

herpesviruses isolated from six sheep and four goats by restriction endonuclease analysis and radioimmunoprecipitation. Am J Vet Res 49:781-785. 16. Whetstone C, Miller J, Bortner D, et al.: 1989, Changes in the restriction endonuclease patterns of four modified-live infectious bovine rhinotracheitis virus (IBRV) vaccines after one passage in host animal. Vaccine 7:527-532. 17. Whetstone CA, Miller JM, Bortner DM, et al.: 1989, Changes in the bovine herpesvirus 1 genome during acute infection, after reactivation from latency, and after superinfection in the host animal. Arch Virol 106:261-279. 18. Whetstone CA, Wheeler JG, Reed DE: 1986, Investigation of possible vaccine-induced epizootics of infectious bovine rhinotracheitis, using restriction endonuclease analysis of viral DNA. Am J Vet Res 47:1789-1795. 19. Wyler R, Engles M, Schwyzer M: 1989, Infectious bovine rhinotracheitislvulvovaginitis (BHV-1). In: Herpesvirus diseases of cattle, horses, and pigs, ed. Wittmann G, pp. 1-72. Kluwer Academic Publ., Norwell, MA.

Experimental transmission of epizootic bovine abortion (foothill abortion)

Advances in defining the biology of epizootic bovine abortion (EBA), including identification of the etiologic agent, have been hampered by the inability to reproduce the disease with confidence. Experimental reproduction of EBA, by feeding the tick vector Ornithodoros coriaceus on susceptible pregnant heifers, is not reliable. The primary objectives of this study were to identify specific tissue(s) obtained from EBA-infected fetuses that could transmit the disease, and then utilize such an infectious challenge system to better define the pathogen, host immunity and geographic distribution of the agent. Described here is the ability to routinely reproduce EBA following inoculation of cryopreserved suspensions of homogenized thymus into susceptible pregnant heifers. This challenge system permitted experiments demonstrating the agent was non-filterable, inactivated upon sonication and susceptible to antibiotics. These findings suggest a prokaryotic microbe and represent a major advance in EBA research. Additional experiments demonstrated that inoculation of the cryopreserved EBA-infectious tissue into heifers, prior to breeding, conferred immunity. Furthermore, such immunized heifers were resistant to challenge with heterologous sources of infectious tissue, suggesting monovalent vaccine development might be feasible. Lastly, challenge studies employing animals from Central Nevada, an area considered free of EBA, demonstrated partial immunity, suggesting the pathogen, and possibly the disease, enjoy a broader distribution than previously thought.

Relationships of milk culture status at calving with somatic cell counts and milk production of dairy heifers during early lactation on a Californian dairy

Abstract Four-quarter, composite milk samples were collected from 339 heifers calving for the first time in a large Californian dairy which consistently had low herd somatic cell counts and low prevalence of major mastitis pathogens. The milk samples were collected on average at 6.4 days post partum (range 1–17). Thirty-nine percent of the heifers were subclinically infected with coagulase-negative Staphylococcus spp. Other results were: no growth, 29%; coliform only, 16%; Streptococcus spp. only, 11%; Streptococcus spp. and coagulase-negative Staphylococcus spp. only, 4%; others, 1%. The somatic cell counts and milk production were not significantly different ( P > 0.05) between culture groups over the first five monthly Dairy Herd Improvement test periods. Somatic cell counts decreased significantly after the first test period within the Streptococcus spp. group ( P Staphylococcus spp. group ( P P Staphylococcus spp.) had no significant effect on average somatic cell counts or milk production during early to middle lactation.

Whole blood selenium concentrations in endurance horses.

Exercise causes an increase in the production of reactive oxygen species, which can result in oxidant/antioxidant disequilibrium. Deficiency of antioxidants can further alter this balance in favor of pro-oxidation. Selenium (Se) is one of many antioxidant catalysts, as a component of the glutathione peroxidase enzymes. Soils and forages vary widely in Se concentration and a deficient diet can lead to sub-clinical or clinical deficiency in horses. Endurance horses are prone to oxidative stress during long periods of aerobic exercise and their performance could be affected by Se status. This study investigated the blood Se concentration in a group of endurance horses (n=56) residing and competing in California, a state containing several regions that tend to produce Se-deficient forages. The rate of Se deficiency in this group of horses was low, with only one horse being slightly below the reference range. Higher blood Se concentrations were not associated with improved performance in terms of ride time. There was no significant difference in Se concentration between horses that completed the ride and those that were disqualified, although blood Se concentrations were significantly higher in horses that received oral Se supplementation. An increase in blood Se concentration was observed following exercise and this warrants further study.

The Correlation of Potassium Content and Moisture in Bovine Liver Samples Analyzed for Trace Mineral Concentrations

Beef cattle in the United States are often found to be deficient in essential trace minerals such as copper and zinc. Established reference ranges for mineral concentrations exist and usually designate a concentration as adequate, marginal, deficient, or excessive. This research investigates a new method of interpreting detected elemental concentrations in bovine liver that will add confidence to the final diagnosis. This is based on the hypothesis that a correlation exists between potassium concentration and moisture in a bovine liver sample. This relationship between potassium and moisture content enables the diagnostician to more accurately predict mineral concentrations and wet weight regardless of sample moisture loss. Correlations were found between potassium content and percentage of moisture in experimental samples, clinical biopsies, and a validation study, to a statistical significance of P < 0.001. Experimental samples had a correlation coefficient of R 2 = 0.95 and the mathematical relationship y = 2513.2x −1.0662. Clinical biopsies had a correlation of R 3 = 0.83 and the mathematical relationship y = 2203.4x −0.991. The validation study had a correlation of R 2 = 0.55 and a mathematical relationship y = 2321.4x −0.952. An exponent of −1 is predicted by conservation of potassium mass. These findings have practical significance in maintaining and improving cattle growth, health, reproduction, and food safety.

Effect of a nutritional reconditioning program for thin dairy cattle on body weight, carcass quality, and fecal pathogen shedding

OBJECTIVE To assess changes in body weight, carcass quality, and fecal pathogen shedding in cull dairy cows fed a high-energy ration for 28 or 56 days prior to slaughter. DESIGN Randomized clinical trial. ANIMALS 31 adult Holstein dairy cows. PROCEDURES Cows were randomly assigned to a control (immediate slaughter) group or a 28-day or 56-day feeding group. Cows in the feeding groups received a high-energy feed and were weighed every 7 days. Carcasses were evaluated by USDA employees. Fecal and blood samples were collected at the start and end of the feeding periods. RESULTS Body condition score and adjusted preliminary yield grade were significantly increased in both feeding groups, compared with values for the control group; body weight, hot carcass weight, dressing percentage, and ribeye area were significantly increased after 56 days, but not after 28 days, compared with values for the control group. Average daily gain and marbling score were significantly lower after feeding for 28 days versus after 56 days. Prevalence of Escherichia coli O157:H7 shedding in feces decreased from 14% to 5.6%, but this difference was not significant. Cows seropositive for antibodies against bovine leukemia virus that had signs of lymphoma and lame cows had a low average daily gain. Net loss was

Investigation of Anaplasma marginale Seroprevalence in a Traditionally Managed Large California Beef Herd

71.32/cow and

Vitamin E and selenium concentrations in month-old beef calves

112.80/cow for the 28-day and 56-day feeding groups, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Feeding market dairy cows improved body condition and carcass quality. Cows seropositive for antibodies against bovine leukemia virus that have signs of lymphoma and lame cows might be poor candidates for reconditioning.