Abstract #W108

# W108
Ano-genital distance as a possible indicator of embryo yield and viability in superovulated Holstein cows—A preliminary report.
I. Rajesh*1, J. E. Carrelli1, M. Gobikrushanth1, D. J. Ambrose1,2, 1Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada, 2Livestock Systems Section, Alberta Agriculture and Forestry, Edmonton, AB, Canada.

Ano-genital distance (AGD) is the distance from the center of the anus to the base of the clitoris in dairy cows, and considered an indicator of prenatal androgen exposure. In our previous work (J Dairy Sci 2017; 100:9815–23) first- and second-parity Canadian Holstein cows with long AGD had lower pregnancy outcomes to first and subsequent artificial inseminations compared with those with short AGD. Consequently, we hypothesized that cows with long AGD have reduced embryo yield and viability compared with cows with short AGD. To determine if embryo characteristics (yield and viability) differed among cows of long and short AGD categories, AGD was measured using digital calipers in 10 Holstein cows that had been previously subjected to superovulation and embryo collection. Cows were classified into either short (≤127 mm; n = 5) or long (>127 mm; n = 5) AGD categories based on the optimum (127 mm) AGD threshold that predicted pregnancy outcomes in our previous report. Data were analyzed using FREQ and GENMOD procedure of SAS. The overall number of structures, fertilized ova, and viable embryos recovered were 73, 54, and 49, respectively. The proportion of total structures tended (P = 0.09) to be greater for cows with short AGD than those with long AGD (58 [42/73] vs. 42 [31/73] %). The proportion of fertilized ova (61 [33/54] vs. 39 [21/54] %) and viable embryos (63 [31/49] vs. 37 [18/49] %) were greater (P ≤ 0.05) for cows with short AGD than those with long AGD. However, within short and long AGD categories, the proportion of fertilized ova out of total structures collected did not differ (79 [33/42] vs. 68 [21/31] %). Likewise, the proportion of viable embryos out of total structures (74 [31/42] vs. 58 [18/31] %) and the proportion of viable embryos out of fertilized ova (94 [31/33] vs. 86 [18/21] %) from each of short and long AGD categories did not differ. In summary, preliminary findings indicate that superovulated Holstein cows with short AGD have greater embryo yield and viability than cows with long AGD. These results need to be confirmed with a larger sample size.

Key Words: embryo characteristics, fertilization, fertility