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  • Author or Editor: Bradley E. Seguin x
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Summary

Use of prostaglandin F products (pg) in dairy cows was studied by use of computerized reproductive herd health data compiled from 29 dairy herds in Minnesota and Wisconsin during 1983 through 1988. Treatment with pg was recorded in 1,856 of 7,139 (26.0%) complete lactations. More than 1 treatment with pg was administered in 534 of the 1,856 (28.8%) lactations in which pg were used. The proportion of lactations in which treatment was used varied among herds and years, and was associated with the proportion of cows in which natural breeding was attempted and, to a lesser extent, with estrus detection index and conception rates; these associations were potentially modified by time between veterinary herd health visits. Calving-to-treatment intervals (mean ± sd) were 100.4 ± 55.1 days for first treatments only, and 116.2 ± 66.1 days for all treatments. These values varied considerably among herds and years and among reasons for treatment. Much of the variation in proportions of lactations in which treatment was used and in the time of treatment within lactations could not be accounted for with the variables included in this study, and was probably related to individual considerations for each cow.

Free access
in Journal of the American Veterinary Medical Association

Summary

Luteinizing hormone (lh) and acth concentrations were measured in plasma from 7 cows to determine whether acth secretion changes with the phase of the estrous cycle, and to determine whether any acth peaks are associated with lh peaks. Blood was collected every 5 minutes for 190 minutes during the luteal and follicular phases of the estrous cycle. Radioimmunoassays were used to measure acth and lh in plasma. Mean concentration of acth in all cows did not differ significantly between luteal (35.1 ± 8.0 pg/ml) and follicular (37.5 ± 9.4 pg/ml) phases of the estrous cycle. Mean concentration of luteal-phase lh of all cows (2.0 ± 1.1 ng/ml) was significantly (P < 0.01) lower than mean concentration of follicular-phase lh (5.4 ± 1.6 ng/ml). Frequency of peaks in acth concentration was low during the sampling period. Mean number of luteal-phase acth peaks (0.29 ± 0.49) was not significantly different from that of follicular-phase samples (0.43 ± 0.53). Unlike acth, mean frequency of lh peaks was significantly (P < 0.05) higher in plasma from cows in the follicular phase of the estrous cycle (2.9 ± 0.7), compared with that from cows in the luteal phase (0.29 ± 0.49).

Free access
in American Journal of Veterinary Research

Summary

A total of 727 blood samples from female calves born co-twin to male calves were examined cytogenetically for freemartinism between 1978 and 1992. Six hundred calves (82.5%) were determined to be freemartins, and 127 (17.5%) were determined not to be freemartins. The percentage of calves determined not to be freemartins was substantially higher than the 8% reported for an unselected population of female co-twins. We concluded that some obvious freemartins were eliminated prior to submission of samples for confirmatory cytogenetic diagnosis, and that only a small percentage of the estimated 93,000 female calves born co-twin to male calves annually are so examined. Therefore, probably a large number of female co-twins that are not truly freemartins are sold to slaughter every year. We propose that obvious freemartins be identified by use of the vaginal-length test and that the remaining clinically questionable calves be differentiated cytogenetically. This combination of procedures could prevent unnecessary economic losses and preserve important genetic material.

Three animals with chromosomal anomalies were found during examination of samples for freemartinism. Cytogenetic evaluation for freemartinism thus offers the added value of simultaneous surveillance for cytogenetic aberrations in male and female cells of a sample.

Free access
in Journal of the American Veterinary Medical Association