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

Recent observations by stakeholders suggested that ecosystem changes may be driving an increased incidence of bovine erythrocytic anaplasmosis, resulting in a reemerging cattle disease in California. The objective of this prospective cohort study was to estimate the incidence of Anaplasma marginale infection using seroconversion in a northern California beef cattle herd. A total of 143 Black Angus cattle (106 prebreeding heifers and 37 cows) were enrolled in the study. Serum samples were collected to determine Anaplasma marginale seroprevalence using a commercially available competitive enzyme-linked immunosorbent assay test kit. Repeat sampling was performed in seronegative animals to determine the incidence density rate from March through September (2013). Seroprevalence of heifers was significantly lower than that of cows at the beginning of the study (P < 0.001) but not at study completion (P = 0.075). Incidence density rate of Anaplasma marginale infection was 8.17 (95% confidence interval: 6.04, 10.81) cases per 1000 cow-days during the study period. Study cattle became Anaplasma marginale seropositive and likely carriers protected from severe clinical disease that might have occurred had they been first infected as mature adults. No evidence was found within this herd to suggest increased risk for clinical bovine erythrocytic anaplasmosis.

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 $71.32/cow and $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.

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 R2 = 0.95 and the mathematical relationship y = 2513.2x(-1.0662). Clinical biopsies had a correlation of R2 = 0.83 and the mathematical relationship y = 2203.4x(-0.991). The validation study had a correlation of R2 = 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.

Vitamin E and selenium concentrations in month-old beef calves.

Three groups of beef cow and calf pairs were studied to determine plasma vitamin E and blood selenium (Se) concentrations of calves at 1 month old. Group 1 was managed on irrigated pasture and calves received no Se/vitamin E injections at birth. Group 2 was managed on irrigated pasture, and the calves were injected with Se/vitamin E at birth. Group 3 was managed on dry foothill grasslands, and these cows were supplemented with 56.3 mg vitamin E and 3 mg Se daily, and the calves received a Se/vitamin E injection at birth. The plasma concentration of vitamin E in group 1 and 2 cows (9.5 +/- 1.24 and 8.43 +/- 1.0 microg/ml, respectively) was significantly higher than that of the group 3 cows (2.28 +/- 0.42 microg/ml; P < 0.05). The blood Se concentrations in group 3 cows (169 +/- 37 ng/ml) were significantly higher than those in group 1 and 2 cows (36.4 +/- 15.9 and 31.1 +/- 12.5 ng/ml, respectively; P < 0.05). Calf Se was highly correlated to cow Se (r = 0.965), and calf vitamin E was moderately correlated to cow vitamin E (r = 0.605). Calf vitamin E concentrations were consistently lower than cow vitamin E concentrations, and many values would be considered deficient.

Diagnostic considerations for evaluating nutritional problems in cattle.

The advances in testing methodology and in our understanding of the normal nutritional physiology of cattle have given veterinarians valuable tools to assess the nutritional status of cattle. By taking a representative number of appropriate samples, it is now relatively easy and inexpensive to determine the nutritional status of an individual or a group of animals. Also, the effectiveness of supplementation programs can be measured over time as part of an overall preventive medicine program.

Preparing Holstein steer calves for the feedlot.

It is increasingly common to raise Holstein steer calves for entry to feedlot production systems rather than more traditional milk-fed veal production systems. Providing adequate nutritional support for the maintenance and growth of Holstein calves is essential in preparing them for a commercial feedlot environment. In this article, the dietary requirements of preruminant calves are reviewed and examples of evaluating milk diets for Holstein calves are detailed. The importance of the transition between milk feeding and grain-forage diets is discussed. Aspects of disease prevention, such as coccidiosis control and colostrum feeding, are also discussed. The reader will gain practical tools to use in preventive medicine programs involving Holstein steers being prepared for commercial feedlots.

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

Epizootic bovine abortion (EBA) is endemic in California's 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.

Identification and Detection of a Virus Associated with Strawberry Pallidosis Disease.

The etiology of pallidosis, a disease of strawberry identified more than 45 years ago, remains unknown. We report a putative agent of the disease, a virus belonging to the Crinivirus genus of the Closterovirideae family. A sensitive reverse transcription-polymerase chain reaction (RTPCR) test has been developed. Polyclonal antibodies that can be used to detect the virus in petiole tissue blots were developed using a recombinant virus coat protein. The nucleotide sequences of regions of the viral genome that encode the heat shock protein 70 homolog and the major coat protein were obtained. Alignments of the major coat protein show that the virus isolated from strawberry plants positive for pallidosis is most closely related to Cucumber yellows virus (syn. Beet pseudo-yellows virus) and Cucurbit yellow stunt disorder virus, members of the Crinivirus genus.

Electron delocalization in cross-conjugated p-phenylenevinylidene oligomers.

The synthesis, structure, and electronic properties of a series of cross-conjugated p-phenylenevinylidene oligomers with one to four double bonds are reported. The X-ray crystal structure of the compound with two double bonds reveals a nonplanar conformation with torsion angles about the C(phenylene)-C(vinylidene) and C(phenyl)-C(vinylidene) formal single bonds of 39.5(2) degrees and 30.5(2) degrees, respectively. Admixture of quinoid character in the ground state is observed. Infrared and Raman spectroscopy do not provide a clear picture of the degree of electron delocalization in the series, since the C=C stretching mode does not adequately reflect the C=C bond order and has a local nature. In contrast, electronic spectra and electrochemical data, as well as AM1 and PPP/SCF calculations, reveal that the cross-conjugated compounds basically behave as linearly pi-conjugated systems in the sense that molecular orbitals are delocalized over the entire structure and systematically change in energy. The electronic interaction between the repeating units is, however, not very strong, which has the consequence that spatial extension of the molecular orbitals does not lead to a red shift of the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) electronic transition. This is related to the feature that the modest narrowing of the HOMO-LUMO gap with the chain length is accompanied by a relatively large reduction of electron repulsion. This finding implies that care should be taken in the use of electronic spectra for the evaluation of conjugation phenomena.

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.