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  • Author or Editor: Donald Hanks x
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Summary

Amount of circumocular pigmentation and incidence of ocular squamous cell tumors were evaluated in dams representing diverse cattle breed types. Each dam was examined twice annually during a specific stage in the life cycle (3.5 to 9.5 years old). Overall, 28.3% of dams in the herd developed at least 1 ocular squamous cell tumor. Breed groups differed (P < 0.01) in amount of circumocular pigmentation and incidence of tumors. Results indicate that losses from ocular squamous cell tumors in beef herds can be sharply reduced by judicious choice of breed types.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Thirty-five heifers were allotted to 3 groups. Group 1 (control) consisted of 10 heifers that were not vaccinated and were challenge exposed by breeding to infected bulls. Group 2 (natural challenge exposure) consisted of 10 heifers that were vaccinated and challenge exposed by breeding to infected bulls. Group 3 (experimental challenge exposure) consisted of 15 heifers that were vaccinated and challenge exposed by breeding to infected bulls and by intravaginal inoculation with 107 Tritrichomonas foetus. Total immunoglobulin concentrations and specific trichomonal antibodies were determined in serum and vaginal secretions of heifers, using radial immunodiffusion and elisa procedures.

Control heifers remained infected for a mean of 10.6 weeks (range, 0 to 18 weeks), and heifers of the natural and experimental challenge-exposure groups remained infected for 3.2 and 5.0 weeks, respectively (range, 0 to 12 weeks). Total serum and cervicova- ginal mucus concentrations of IgM, IgA, IgG1, and IgG2 did not change significantly after vaccination or challenge exposure. However, elisa titers of total trichomonal antibodies increased up to 1:10,000 (range, 1:400 to 1:10,000) in serum after vaccination, and increased approximately tenfold above background in cervicovaginal mucus. In serum, the predominant trichomonal antibody isotype was IgG1, although trichomonal IgA and IgM antibodies also increased. The predominant trichomonal antibody detected in cervicovaginal mucus was IgA. Antibody titers in serum and cervicovaginal mucus of vaccinated heifers were not increased by infection. However, in control heifers, the total local trichomonal antibody response increased three- to fivefold after infection. In these heifers, specific antibodies in serum were predominantly IgGI and local (cervicovaginal) antibodies were predominantly IgA.

Free access
in American Journal of Veterinary Research

Summary

To test the efficacy of a polyvalent Tritrichomonas foetus vaccine, 130 nulliparous heifers were randomly assigned to either receive the test T foetus vaccine or to serve as nonvaccinated controls. The polyvalent test vaccine consisted of a Campylobacter fetus/Leptospira canicola-grippotyphosa-hardjo-icterohaemorrhagiae-pamona bacterine containing 5 × 107 killed T foetus/dose. The polyvalent control vaccine consisted of the aforementioned formulation without T foetus. Heifers were administered 2 doses of control or experimental vaccine at 3-week intervals. Heifers were bred to T foetus-infected bulls and their conception and pregnancy rates were determined throughout gestation. In addition, serum samples were analyzed to determine induced concentrations of antitrichomonal antibodies and vaginal secretions were sampled to determine T foetus infection rates in control and vaccinated animals. One week after each of the 15-day breeding periods, 60% (6 of 10) of tested vaccinates and 80% (8 of 10) of tested control animals were T foetus culture-positive. The mean duration of infection of vaccinates was 3.8 weeks (± 7.5 days), compared with 5.4 weeks (± 7.5 days) of infection for control heifers. All vaccinates developed increased immunofluorescence and serum neutralizing antibody titers following the first immunization, and had additional increases of at least fourfold in response to the second injection. In contrast, no consistent increase in immunofluorescence or serum neutralizing antibodies was observed in control animals.

Conception rates were 89.2% for vaccinates and 85.9% for control animals 30 days after breeding and 80 to 90% of these remained pregnant 60 days after breeding. However, within the next 4 months, the pregnancy rate of control heifers decreased to 30% for those that had conceived. During the same 4-month period, more than 60% of vaccinated heifers remained pregnant. Significantly, 62.5% of heifers vaccinated against T foetus produced calves, whereas only 31.5% of control heifers produced calves. These findings indicate that the polyvalent test vaccine induced an immune response that was effective in lowering the rate of T foetus infection, decreasing the duration of infection, and reducing losses in calf production attributable to early fetal death and abortion caused by T foetus infection.

Free access
in American Journal of Veterinary Research