| Abstract: | Eighty-five postpartum Holstein cows were randomly assigned to receive 0, 50, 100, or 250 micrograms of the gonadotropin-releasing hormone product, Procystin when follicular cysts were diagnosed by palpation per rectum. Accurate reproductive records were maintained, and milk samples were collected at the time of diagnoses for assay for progesterone. An additional 101 cows were injected with only the 100 micrograms dose of Procystin when cysts were identified. Data showed that days from treatment to first observed estrus decreased with increasing doses of Procystin with no advantage of 250 micrograms over 100 micrograms. Days open and conception rates were similar among the treatment groups. Cows with less than 1 ng/ml progesterone in their milk at the time of treatment returned to estrus sooner than cows with progesterone concentrations greater than 1 ng/ml. In addition, gonadotropin-releasing hormone administered to those cows with low progesterone at the time of treatment led to significantly increased progesterone concentrations by 7 and 14 d posttreatment. We conclude that although Procystin administration hastened estrus of cows with ovarian cysts, breeding practices on the farms did not lead to an improvement in reproductive efficiency of the cows that possessed cysts. |
