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  • Author or Editor: Ramon C. Littell x
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Abstract

Objective—To determine the effect of a controlled-release monensin capsule administered at cessation of lactation on incidence of calving-related disorders, fertility, and milk yield in dairy cows.

Animals—290 dairy cows treated with monensin and 290 untreated control cows.

Procedure—Treated cows received a capsule that released monensin at 335 mg/d for 95 days. Incidence of calving-related disorders; daily milk yield up to 20 days postpartum; test-day milk yield, fat, protein, and mature-equivalent 305-day milk production; and body condition score at calving were determined. Reproductive variables were conception rate at first service, pregnancy rate, and calving-to-conception interval.

Results—Cows treated with monensin were 2.1 times as likely to develop dystocia and 0.8 times as likely to develop metritis as control cows. For milk yield, there was an interaction of treatment ×time ×parity. In multiparous cows, monensin significantly improved milk yield at test days 4 and 7. In addition, monensin increased body condition score at calving.

Conclusions and Clinical Relevance—Despite increasing the likelihood of developing dystocia and metritis, administration of monensin improved the lactational performance of multiparous cows and may be a promising additive for use at the time of cessation of lactation.

Full access
in American Journal of Veterinary Research

Summary

Experimental and field trials were conducted to evaluate an elisa for its ability to detect Trichinella-infected domestic swine and to compare elisa results with muscle-digestion test results. The elisa used was a commercial double-antibody kit, containing an excretory-secretory antigen, and was evaluated principally for epidemiologic use. Experimentally induced infection in swine (4 groups of 3 pigs each; inoculated with 0, 50, 500 or 5,000 larvae) was detected as early as postinoculation week 4, with seroconversion of all inoculated swine by postinoculation week 8. The rate of seroconversion appeared to be affected by initial larval dose, time after inoculation, and immunocompetence of the individual host. Determination of antibody kinetics generally revealed rapidly increasing antibody titer, followed by its steady decrease in most pigs. Once seropositive, however, all pigs remained seropositive for the duration of the 10-week study. Presence of muscle larvae was confirmed in all infected pigs at termination of the study. We recognize that the experimental conditions may not be truly representative of those under which natural infection develops in pigs; however, the elisa detected an infected pig with muscle larval density of 0.87 larvae/g of tissue. Results of a field trial (n = 310) indicated no muscle digestion test-positive pigs (35 g of diaphragm muscle digested/pig), but 3 samples tested positive by elisa for specificity of 99.0%.

Free access
in American Journal of Veterinary Research

Summary

A survey was conducted from 1986 through 1987, for which an ELISA was used to obtain information on the prevalence of Mycobacterium paratuberculosis infection in cattle of Florida. Results revealed prevalence of 8.6% in beef cattle and 17.1% in dairy cattle. In beef and dairy cattle, prevalence increased with increasing herd size. It was concluded that ELISA-detectable circulating antibodies to M paratuberculosis are widespread in cattle of Florida.

Free access
in Journal of the American Veterinary Medical Association