Search Results

You are looking at 1 - 7 of 7 items for

  • Author or Editor: James F. Evermann x
  • Refine by Access: All Content x
Clear All Modify Search

Summary

Bovine leukemia virus (blv) infection and culling of cows in a commercial dairy herd were evaluated to determine whether a relation existed between the 2 factors. Cattle from the study population, a Holstein dairy herd consisting of approximately 400 milking cows, were tested for antibodies to blv, using the agar gel immunodiffusion test, semiannually for 2 years, annually for 2 years, and when cattle were culled. Complete records of blv test results were available for 849 (79%) of the 1, 078 cattle that had at least 1 test during the study period. Using the Cox hazard model, the cull hazard rates (culls/cow-months) were greater for blv seropositive cows than for seronegative cows > 36 months old. Hence, among older dairy cows, blv-infected cows were culled prematurely, compared with uninfected cows.

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Summary

To determine whether rectal palpation, using common obstetrical sleeves, serves as a mode of transmission of bovine leukemia virus in dairy cattle, field studies were conducted at 2 dairies. At a commercial dairy, significant difference was not observed in rate of seroconversion in heifers and cows in which the same sleeve or new sleeves were used for palpations. At a university dairy, where cattle were used to teach dairy husbandry and veterinary procedures, significantly (P < 0.02) greater rate of seroconversion was observed in heifers and cows palpated with unwashed common sleeves than that observed in heifers and cows palpated with sleeves washed between use. Although rectal transmission of bovine leukemia virus under field conditions was documented, it was related to frequency of palpation and age of cattle.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To examine sera obtained from dairy and beef cattle to detect antibodies against vesivirus and compare seroprevalence among cattle within the sample population.

Sample Population—Cattle sera from 8 western states and Maryland submitted to the Washington Animal Disease Diagnostic Laboratory during 1999 and 2000.

Procedure—Sera were analyzed for vesivirus-specific antibodies by use of a recombinant vesivirus–San Miguel sea lion virus serotype 5–capsid peptide antigen in an indirect ELISA.

Results—Overall, 693 sera were tested and 105 (15.2%) had positive results. Seropositive cattle were from 7 states (all cattle from Montana and Maryland 10 and 4, respectively were seronegative). Overall seroprevalence for antivesivirus antibody in herds ranged between 0% and 80% (median, 14%). Higher antibody prevalence was significantly associated with older age, dairy rather than beef cattle, and reasons for submission. Logistic regression of factors (abortion, respiratory tract disease, and all other reasons for sample submission) revealed that older age and other reasons were independently associated with higher seroprevalence. Higher seropositive optical density values for the ELISA were observed among older cattle and cattle that aborted, compared with values for cattle with respiratory tract disease or other reasons for submission.

Conclusions and Clinical Relevance—This laboratory-based surveillance sample provided a point estimate of seroprevalence against vesivirus among cattle in 9 US states. This suggests that vesivirus infection is widespread with high prevalence in some herds. Risk factors associated with vesivirus seroprevalence in beef and dairy cattle should be confirmed in population-based studies.

Full access
in American Journal of Veterinary Research