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Summary

Four virgin beef heifers were inoculated intravaginally with 7 × 106 Tritrichomonas foetus organisms. Protozoal colonization of the vagina, cervix, and uterus developed within the first week after inoculation. Protozoa were no longer detected in secretions from these regions at approximately the same time in each heifer. Trichomonads were detected in reproductive tract secretions for 13 to 28 weeks. Eight weeks after clearance of trichomonads from the reproductive tract, a second infection was established in 2 of the 4 heifers by intravaginal inoculation of T foetus. The second infections were maintained for up to 4 weeks.

The diagnostic sensitivity of wet-mount examination of the reproductive tract secretions was 30%, compared with 78% for culture of trichomonads in secretions. Collection and culturing of specimens of cervical and vaginal mucus provided the most reliable method for diagnosis of trichomoniasis during induced infection of heifers.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To develop a model to evaluate the effect of vaccination against Tritrichomonas foetuson reproductive efficiency in beef herds.

Sample Population—A beef herd of 300 cows and 12 bulls (8 bulls ≤ 3 years old and 4 bulls > 3 years old).

Procedure—The model was developed by use of data for various risk factors and vaccine efficacy. The reference herd was considered to be one in which T foetus had been diagnosed and bulls were tested for T foetus before the breeding season. Five thousand iterations were run for each of 13 simulations, with each simulation representing a separate combination of risk factors.

Results—In all simulations, vaccination resulted in significantly higher calving incidence than nonvaccination. Shared grazing was found to be the most significant risk factor for a decrease in calving incidence attributable to T foetus infection, followed in importance by lack of testing before the breeding season and a higher proportion of old bulls. Combinations of risk factors contributed to a loss of income of up to 22%, some of which could be blunted by vaccination.

Conclusions and Clinical Relevance—Highest calving incidence is achieved when all bulls are tested for T foetus before the breeding season and all bulls with positive culture results are culled. Avoiding all risk factors is better than vaccinating, but when this is not feasible for a given herd, the results of this simulation indicate that proper vaccination can decrease economic losses attributable to abortions caused by T foetus. (Am J Vet Res 2004;65:770–775)

Full access
in American Journal of Veterinary Research

SUMMARY

Individual card records of all cows that began 1 or more lactations between the inclusive dates of Jan 1, 1976 and Dec 31, 1986 were obtained from a California dairy herd. Calving date, lactation number, physical examination date, conception date, and clinical findings pertinent to cystic ovarian disease (cod) were extracted from the records. Lactation-specific data were organized into cohorts by quarter and year in which lactation began, and the following estimates were calculated for each of the 44 cohorts: separate actuarial cumulative incidences for cows in their first lactation, cows in the second or later lactation, and all cows combined; separate proportions of the incident cases that were in their second or greater lactation and that had recurred from any previous lactation; proportions of the incident cases that had recurrence of cod 1 or more times, and recurrence 2 or more times during the lactation; and the mean number of days in lactation at diagnosis of the incident case. Time-series analysis and multiple-regression modeling procedures were used to characterize changes in the overall incidence rate over the study period and to describe the contribution of additional measures to the dynamics of the incidence rates. The quarterly actuarial cumulative incidences of cod increased concurrently with the increased incidence among cows in the second or later lactation. Neither the proportion of incident cases that were diseased during a previous lactation nor the proportion of cases that were in the second or later lactation contributed to the observed changes in the overall incidence rate. The proportions of incident cases that recurred 1 or more times during the lactation did not increase, but the proportions that had 2 or more recurrences increased equivocally.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of estradiol cypionate (ECP) on measures of reproductive efficiency in postparturient dairy cows.

Design—Randomized clinical trial.

Animals—273 cows in a single herd in California.

Procedure—Twenty-four hours after parturition, 122 cows were treated with ECP (4 mg, IM); the remaining 151 cows were untreated controls. Percentages of cattle with abnormal findings during uterine palpation 27 to 40 days after parturition were compared between groups, along with days to first artificial insemination (AI), percentages of cows that were not pregnant after the first AI, and days to pregnancy.

Results—Treatment with ECP did not have a significant effect on whether results of uterine palpation 27 to 40 days after parturition were abnormal, days to first AI, or odds that a cow would be pregnant after the first AI. Treatment with ECP appeared to have a negative effect on days to pregnancy (hazard ratio, 0.72)

Conclusions and Clinical Relevance—Results suggest that prophylactic administration of ECP during the early postparturient period in dairy cows did not have measurable beneficial effects on reproductive efficiency. (J Am Vet Med Assoc 2001;219:220–223)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify potential risk factors for embryonic loss before 35 to 42 days of gestation in dairy cattle.

Design—Prospective observational study.

Animals—381 cows.

Procedure—Body condition score was determined at the time of artificial insemination (AI; day 0) and on days 20, 23, and 27 and between days 35 and 41; serum progesterone concentration was measured on days 0; 20 or 21; and 23, 24, or 25. Cows were excluded from analyses if day 0 serum progesterone concentration was ≥ 1.0 ng/mL and classified as pregnant on day 23 if serum progesterone was > 1.5 ng/mL on day 20 or 21 and day 23, 24, or 25. Cows were examined via transrectal ultrasonography on day 27 or 28 and rectally palpated for pregnancy on days 35 to 41.

Results—39% of cows that were pregnant on day 23 lost their embryo by day 27, and 18% of cows that were pregnant on day 27 or 28 were not pregnant on days 35 to 41. Breeding a pregnant cow posed the greatest risk for embryonic loss at both time periods. Mean serum progesterone concentrations on day 21 or 22 and day 23, 24, or 25 were lowest for cows that lost an embryo between days 24 and 28. Cows with a linear somatic cell count score > 4.5 before AI were twice as likely to lose the embryo by 35 to 41 days, compared with cows with a score < 4.5.

Conclusions and Clinical Relevance—Results suggest that embryonic loss could be reduced by more accurate estrus detection, reducing mastitis, and strategies to improve progesterone concentration after breeding. (J Am Vet Med Assoc 2005;226:1112–1118)

Full access
in Journal of the American Veterinary Medical Association

Objective

To compare sensitivity of a generic trypticase-yeast extract-maltose (TYM) medium versus a commercial nutrient medium in the diagnosis of Tritrichomonas foetus infection in heifers and to assess sensitivity when incubation of samples inoculated into commercial medium pouches is delayed overnight.

Design

Prospective study.

Animals

30 virgin beef heifers.

Procedures

20 heifers vaccinated with a trichomonad antigen and 10 unvaccinated control heifers were exposed at synchronized estrus by intravaginal instillation of 106 T foetus organisms. Cervicovaginal mucus samples were collected every other week for 10 weeks from controls and once (10 weeks after exposure) from vaccinated heifers. Samples were inoculated into both media and immediately incubated at 37 C (98.6 F). A duplicate inoculation from controls was made into commercial medium, and the pouch was shipped overnight to a diagnostic laboratory without prior incubation.

Results

For 40 of 50 samples from control heifers, there was agreement on diagnoses between media. There was agreement on a positive diagnosis for 3 of 20 samples from vaccinated heifers and on a negative diagnosis for 15 of these 20 samples. For samples shipped overnight before incubation, there were 10% fewer positive diagnoses, compared with samples incubated immediately in commercial medium and 10% more positive diagnoses, compared with samples immediately incubated in TYM.

Clinical Implications

Use of the commercial medium is a more sensitive indicator of current infection in heifers than use of generic TYM medium. In herds where infection prevalence is high, this method is likely to identify more infected females, an important consideration when control programs include culling of infected cows. (J Am Vet Med Assoc 1998;213:519-522)

Free access
in Journal of the American Veterinary Medical Association