Influence of cornual insemination on endometrial damage and microbial flora in the bovine uterus

The objectives were to determine effects of cornual insemination on endometrial characteristics and uterine bacterial flora. Forty cows were assigned randomly (10/group) to each of the following treatments: 1) control--no uterine manipulation; 2) uterine body insemination--deposition of the inseminate at the internal cervical os; 3) cornual insemination--one-half of inseminate deposited into each uterine horn anterior to the internal bifurcation and 4) cornual insemination plus endometrial biopsy--insemination into each uterine horn and trauma induced by endometrial biopsy. Animals were slaughtered and reproductive tracts were removed 5 d after treatment. Bacterial populations of the uterine lumen were evaluated by both flushings and swabbings of each horn. Treatment did not influence the presence of luminal bacteria as determined by flushing or swab samples. Gross endometrial characteristics were quantitated in all tracts. Characteristics considered were total endometrial surface area, discolored regions that appeared to be distinctly darker than the remaining portion of the endometrium and obvious surface damage. Discolored regions were evaluated as both total areas and percentage of endometrium. Treatment did not influence total or percent discolored areas. Microscopic evaluation of these tissues revealed increased edema when compared with nondiscolored regions but no disruption of the luminal epithelium was found. Surface damage was found only in the biopsied treatment group. Observation of the endometrium revealed that extensive regeneration occurred by 5 d after treatment. The data suggest that cornual insemination does not result in uterine trauma or bacterial presence 5 d after breeding, and the endometrium is capable of regeneration after trauma during estrus.