Browse

You are looking at 51 - 53 of 53 items for :

  • Food Animal Economics x
  • Refine by Access: All Content x
Clear All

Summary

Sixty cow-half herds of more than 50 cows each were randomly selected for a prevalence survey of bovine trichomoniasis in California. Herd size, as judged by the number of bulls, ranged from 1 to 210 bulls (median = 8; mean = 59 ± 15.8). Preputial smegma was collected from 729 bulls (median = 6 bulls/herd) and cultured for Tritrichomonas foetus. Of 57 herds from which samples were collected, 9 (15.8%) had at least one infected bull. Of the 729 bulls from which samples were cultured, 30 (4.1%) were infected. Correcting for sensitivity of the diagnostic test yielded a prevalence of 5.0%. Infection rates for bulls >3 years old and ≤3 years old were 6.7% and 2.0%, respectively (P > 0.025). Median herd sizes were 14 bulls (range, 6 to 114) for infected herds and 7 (range, 1 to 210) for uninfected herds. These findings suggest that trichomoniasis is common in California beef herds. Because several bulls <4 years old were infected, we suggest that control measures stressing replacement of older bulls with younger ones should be combined with diagnostic procedures in those younger replacements, to ensure that they are not already infected.

Free access
in Journal of the American Veterinary Medical Association

Summary

Twelve dairy herds that had participated in the Pennsylvania Dairy Herd Improvement Association (DHIA) program for at least 12 months, that had a 12-month mean DHIA somatic cell count > 700,000 cells/ml, and that had > 25% of lactating cows infected with Streptococcus agalactiae participated in a herd blitz treatment program. Initially, quarter milk samples for bacteriologic culturing were collected from all lactating cows. Subsequently, all cows identified as infected with Str agalactiae were treated, using a commercial penicillin-novobiocin intramammary infusion product. In addition, a herd mastitis management program of postmilking teat dipping and treatment of all cows at the start of the nonlactating period was instituted. Thirty days after the initial herd visit, samples from all lactating cows were again cultured, and cows infected at that time were treated. Twelve months after the initial herd visit, samples from all lactating cows were again cultured.

Mean prevalence of infection with Str agalactiae decreased (P < 0.05) from 23.0% of quarters and 41.6% of cows initially to 3.4% of quarters and 9.3% of cows at 30 days and 1.6% of quarters and 4.2% of cows at 1 year. Mean herd DHIA somatic cell count decreased (P < 0.05) from 918,000 cells/ml initially to 439,000 cells/ml at 30 days and 268,000 cells/ml at 1 year. The mean net increase in 365-day DHIA rolling herd production for the first year after treatment was 512 kg of milk and 14 kg of butterfat.

Benefit-to-cost ratios were estimated for 3 methods of identifying cows for treatment in a blitz treatment program. Analysis revealed similar economic gains for culturing of all lactating cows followed by treatment of those infected with Str agalactiae (benefit-to-cost ratio of 2.28:1), and for treatment of all lactating cows with a DHIA linear somatic cell count score ≥ 4, regardless of infection status (benefit-to-cost ratio of 2.18:1).

Treatment of all lactating cows, regardless of somatic cell count or infection status, was least cost-effective (benefit-to-cost ratio, 1.26:1). It is suggested that blitz treatment, used with postmilking teat dipping and treatment of all cows at the start of the nonlactating period, is an economically justifiable program for herds with high prevalence of Str agalactiae mastitis, and owing to labor considerations, the use of DHIA linear somatic cell counts may be the best method to identify cows for treatment.

Free access
in Journal of the American Veterinary Medical Association

Summary

Three commercial tests that measure progesterone content in milk were evaluated for accuracy of estrus detection. The tests were evaluated on 96 milk samples collected from Holstein cows at a commercial dairy farm in central Florida. The test results were compared with the results of radioimmunoassay on the same sample. Comparisons were made by calculating the sensitivities, specificities, and predictive values. The significance of the statistical association between the tests and the radioimmunoassay was evaluated by use of the McNemar χ2 test. Decision-tree analysis was used to determine the most useful testing strategy, considering both cost and accuracy. The cowside progesterone assay on estrus-mount detector-positive cows was more profitable than use of estrus-mount patches alone. The return on investment was higher with the cowside test, making it preferred as a field test for detecting estrus.

Free access
in Journal of the American Veterinary Medical Association