333 Pregnancy rate obtained with embryos collected after insemination of superovulated cows with sexed sorted semen

Abstract

According to the production objectives of beef or dairy commercial farms, the possibility of gender selection of the offspring is an important tool to optimize the use of genetic and economical resources. The use of sexed sorted semen by flow cytometry to inseminate donors in a MOET program has successfully demonstrated a normal embryo production per cow (Theriogenology 59:513). The aim of this study was to evaluate the pregnancy rate and sex accuracy obtained after transferring embryos collected using sexed semen to inseminate the donors in MOET programs. The semen was provided by our commercial laboratory. Eighteen cows were inseminated with frozen female sexed semen and 22 with frozen male sexed semen. Embryos were collected using a commercial flushing medium with BSA and antibiotics. After the embryos were washed through 10 drops of holding medium, 50 embryos were transferred fresh;; 150 were frozen in 1.5�M ethylene glycol, thawed 10 seconds in air;; and held for 30 seconds in a water bath at 35�C before transferring them. Fresh embryo stage and quality rates were: morula grade 1: 49%, grade 2: 13%; blastocyst grade 1: 34%, grade 2: 4%. Frozen embryo stage and quality rates were: morulae grade 1: 28%, grade 2: 18%; blastocyst grade 1: 47%, grade 2: 7%. The embryo transfers (ET) were performed in previously synchronized recipients injected with two doses of prostaglandin 12 days apart. Thirty days after ET, the diagnosis of pregnancy was done by transrectal ultrasonography (ALOKA 500 Scanner) to asses the pregnancy rate. Sixty days after the ET, fetal sex determination was done. The results are shown in the table 1 below. The pregnancy rates in both fresh and frozen-thawed preselected sex embryos are similar to those obtained with nonpreselected sex embryos (Theriogenology 56:�1401). The high rate of sex accuracy shows the reliability of the technique of sexed sorted semen by flow cytometry to produce preselected sex embryos in superovulated cows. This research was supported by Fundaci�n Margarita Perez Companc.