369 ASSESSMENT OF SEMEN QUALITY FOR PREDICTING RECOVERY OF VIABLE EMBRYOS IN SUPEROVULATED CATTLE

Abstract

Several studies have illustrated a relationship between male fertility and subsequent pregnancy rates following natural service and artificial insemination. However, few studies have evaluated the relationship of semen quality to recovery of viable embryos within a commercial embryo transfer setting. The objective of the current study was to retrospectively evaluate the relationship of semen quality, determined immediately before insemination, and subsequent embryo recovery from superovulated cattle. All donor animals were superovulated and then inseminated (same technician throughout the study) with frozen-thawed semen at 12 and 20 h after onset of estrus with one straw of semen per insemination. Since data were collected from a commercial setting, several different bulls (n = 277) and breeds (n = 33) were included within the analyses; however, the same semen (bull and collection date of semen) was used for each insemination for that respective flush. Immediately following thawing of semen and before insemination, 5 ¼L of semen was obtained from each straw and evaluated by the same individual for concentration, motility, rate of forward movement, direction of movement, and morphology using a phase contrast microscope. Approximately 7 days later, ova/embryos were recovered and defined as unfertilized (not cleaved), degenerate, or viable. Semen was assessed and utilized in 742 recoveries resulting in the evaluation of 9732 ova/embryos. Chi-square analyses were used to explore relationships among semen and fertilization/embryo variables. A complex model addressing combinations of semen variables was developed with logistic regression. Total ova/embryos recovered had a significant impact on embryo data and was included in the model during statistical analyses with the significance level set at P < 0.05. Analyses were conducted only on uterine recoveries in which ova/embryos were collected. Effects of bull and breed were significant on embryo data evaluated but at a very low level of relevance (F < 2.0). Total ova/embryos collected per recovery highly influenced the percentage of cleaved embryos (P < 0.0001). Results indicate that all semen parameters evaluated affected various aspects of embryo development (percent fertilized, viable, or degenerate). In particular, semen morphology was more associated with quality of embryos recovered than the other semen factors measured. Semen classified as excellent-to-good morphology resulted in 59% Quality 1 embryos (percent of fertilized embryos) whereas semen rated fair was intermediate (53.5%) and semen rated poor produced only 29.5% Quality 1 embryos (P < 0.05). In conclusion, semen evaluation within a commercial embryo transfer setting provides some expectation of resulting embryo quality.