The response of cows with cystic ovarian degeneration to luteotropic or luteolytic therapy as assigned by latex agglutination milk progesterone assay

Abstract

Using transrectal palpation criteria, 111 cows were diagnosed to have cystic ovarian degeneration. Pretreatment milk samples were collected for progesterone analysis with a latex agglutination milk progesterone assay. The control group cows were treated with GnRH, regardless of their progesterone concentration (GNRH control). Treatment group cows were assigned to either luteotropic or luteolytic therapy based upon latex agglutination milk progesterone concentration (LA assigned). Gonadotropin releasing hormone or PGF2 alpha were administered to cows with low and high (>3.68 ng/ml) milk progesterone concentration, respectively. Prior work predicted that only 30% of the COD cow population would be classified as high progesterone concentration. To allow for an adequate sampling of PGF treated cows within the LA assigned group, only every third cow was randomly assigned to the GnRH control group. Comparable milk samples were collected from GnRH-treated cows on Day 10 and PGF-treated cows on Day 4 after treatment. Response to therapy was defined as a reversal in the pretreatment versus posttreatment milk progesterone concentration. Response to cystic ovarian degeneration therapy was 52.3% in the 44 GnRH control cows, versus 71.6% in the 67 LA assigned cows (P < 0.05). Within the GnRH control group, the response to therapy was 71.9 and 0.0 % for the low versus high progesterone concentration cows (P < 0.001). Within the LA assigned group, the response to therapy was not different (70.2 and 75.0%) for the low versus high progesterone concentration cows. Cows with cystic ovarian degeneration and high progesterone concentration did not respond to GnRH therapy. The latex agglutination system was an effective means for selecting those cows with cystic ovarian degeneration that required luteolytic therapy.