Ovarian and uterine morphology and function in Angus and Brahman cows

Ovarian characteristics, daily serum progesterone (P4) and estradiol-17 beta (E2) concentrations (d 7 through 17) and uterine luminal secretory protein components and histological variables were evaluated in parous Bos taurus (Angus, n = 20) and Bos indicus (Brahman, n = 19) cows. Cows were slaughtered on d 17 (estrus = d 0) for measurement of ovarian structures, flushing of uteri and removal of uterine tissue for histological evaluation. Cows were placed into one of three reproductive categories: nonpregnant, remnant (flushings contained remnants of embryonic tissue) or pregnant. For ovarian and uterine variables, there were only a few differences among reproductive categories within breeds. For combined categories, weight of the active ovary (containing the corpus luteum) was similar between breeds, but inactive ovarian (P less than .001) and follicular fluid (P less than .01) weights, stromal weight (P less than .01) and number of follicles less than 5 mm in diameter (P less than .01) for both ovaries combined were greater in Brahman than Angus cows. Corpus luteum weight (P less than .001), luteal P4 content (P less than .08) and number of follicles greater than 5 mm in diameter for both ovaries combined (P less than .05) were greater for Angus than for Brahman cows. Overall, mean serum P4 concentrations were greater in nonpregnant (P less than .05), pregnant (P less than .005) and combined (P less than .025) reproductive categories for Angus than corresponding categories of Brahman cows and mean serum E2 concentrations were greater in remnant (P less than .025) and combined (P less than .05) reproductive categories for Angus than corresponding categories of Brahman cows. Mean total uterine luminal protein was greater (P less than .05) in Angus than in Brahman cows for pregnant (23.4 vs 14.7 mg, respectively) and combined reproductive categories (22.4 vs 16.1 mg, respectively). Using electrophoretic analyses, percentage composition of three uterine specific cathode migrating protein bands and quantitative estimates of proteins with molecular weights (MW, X 10(-3)) of 9, 15.5, 34.2, 41.3, 46.2 and 183.1 were greater (P less than .05 to P less than .001) in uterine flushings from Angus than from Brahman cows. Uterine, myometrial and endometrial thicknesses, number of glands/microscopic field and uterine luminal epithelial cell height variables were generally greater (P less than .05 to P less than .001) in pregnant and combined reproductive categories for Angus than for Brahman cows.