AGREEMENT AMONG EVALUATORS OF BOVINE EMBRYOS PRODUCED IN-VIVO OR IN-VITRO

Six experienced individuals evaluated 40 embryos on videotape for stag e of development and quality grade. These 40 observations comprised 15 embryos produced in vivo, 15 embryos produced in vitro, and 10 embryo s that were repeated throughout the videotape. Embryos produced in viv o were recovered from uterine flushings of superovulated heifers 7 d a fter estrus, and embryos produced in vitro were harvested 7 d after in semination of in vitro-matured oocytes. Embryos of various stages (mor ulae, blastocysts, or degenerated) and quality grades (1 = excellent, 2 = good, 3 = fair, 4 = degenerated) were recorded on videotape for ev aluation. After video microscopy, the embryos were stained and the num ber of nuclei per embryo was counted. Six evaluators reviewed the vide otape and the percentage of agreement and kappa (k; agreement beyond c hance) among evaluators were determined for classifications of stage a nd grade. Consistency of each evaluator's responses was estimated usin g the 10 repeated embryos. Agreement within evaluators was higher for stage of embryo development (89.2%) than quality grade (68.5%). Agreem ent among evaluators for stage was slightly higher with embryos produc ed in vivo (85.0%, k = 0.74) than in vitro (72.3%, k = 0.48). Agreemen t among evaluators for grade was similar with embryos from in vivo (61 .0%, k = 0.46) and in vitro (57.7%, k = 0.42) production. For both sou rces of embryos, agreement was substantially better for Grades 1 and 4 than for Grades 2 and 3. The results of this study suggest that good to excellent agreement exists for classifying Day 7 bovine embryos by stage and by extremes of quality grade (Grades 1 and 4) but not by deg ree of abnormal morphology (Grades 2 and 3). Simple grading criteria o f Grade 1 (highest quality), Grade 2 (morphologic defects), and Grade 3 (degenerated) maximized agreement among evaluators.