Recipients will be synchronized with prostaglandins to be in estrus the same time as the donor cow. Those in estrus within 24 hours before or after donor estrus can be used as recipients.

     Since there is no way to predict the number of embryos produced by the donor cow, a sufficient number of recipients are synchronized to anticipate average collection. Ten to fifteen recipients per donor is the usual estimate.

     When embryos are to be frozen, a few recipients should be prepared to implant lower grade embryos which are not freezable.

Collection of Embryos
     Non surgical techniques are used to recover embryos seven or eight days after estrus. The donor is given an epidural block in the area of the tailhead to prevent straining. The vulvar area is scrubbed to prevent contamination.

     A flexible rubber tube called a catheter is gently threaded through the cervix and up into the uterine horns. A small rubber balloon cuff is inflated with fluid to expand and fill the uterine lumen. This prevents any backflow of fluid. There are several holes near the tip of the catheter that precede the inflated cuff. Fluid enters the uterus by means of these holes after being injected through the catheter with a 50 cc syringe.

     Once the fluid is in the uterus, the horn is gently massaged and the fluid (containing the embryos) is drawn back out through the catheter. This process is then repeated in the other uterine horn. The embryos are collected in a zwitterionic buffer solution containing antibiotic/antimycotic.

Embryo Searching
     The fluid flushed through the uterus is filtered through a special filter that traps the embryos but allows the fluid to drain free. All but 50 cc is drained through the filter. This remaining fluid, containing the embryos, is divided into several scored petri dishes to be searched.

     The embryologist searches each dish under a dissecting microscope and upon finding an embryo, removes it with a pipette to be transferred to a small petri dish. All the embryos are placed in these small dishes to later be washed, identified, and classified.

Transfer of Embryos
     Non surgical. Embryos to be transferred non surgically are aspirated into 0.25 ml artificial insemination straws. Air bubbles are placed on either side of the fluid containing the embryo. The straw is fitted into a cassou gun, which is covered with a plastic breeding sheath. The cassou gun is similar to an A.I. gun but slightly longer so that it can go deeper into the uterine horn.

     The recipient is placed in a squeeze chute and given an epidural. After being palpated for a corpus luteum, the cassou gun is inserted mid way up the uterine horn of the recipient and the embryo is deposited in the horn ipsilateral to the corpus luteum. This technique takes considerable practice to achieve satisfactory pregnancy rates.

Results
     From the average donor, approximately eight to ten embryos are collected. Several of these may be unfertilized or degenerate. Approximately seven embryos are of transferable quality and on the average, four or five pregnancies will result after their transfer.

     Approximately 65% of fresh and 60% of frozen embryos result in pregnancies. Your success rates may vary greatly because every donor is different. Some donors will consistently produce large numbers of excellent embryos, while others may only produce a few.

     For beef cattle embryo transfer to be successful, it is essential to pay the strictest attention to detail, thus minimizing any outside influences on the success of the transfer.