How is Embryo Transfer (ET) made?
The ET technique basically consists in the uterine collection of the embryos in pre-implantation state (morula and blastula) of a superior genetic quality cow (donor) and the transferences of each one of those for the cows of low commercial value (recipient). Although considered animals of low value, the recipient has to present functional, sanitary, nutritional and temperamental characteristics that allow them develop their maternal ability.

Superovulation.
Although the growth of some follicles in each estrous cycle, the cows ovulate only one follicle, and the rest of them degenerate; this process is called follicular atresia. Thus, the superovulation is a hormonal treatment that aims at hindering that the follicles become atresic, stimulating them to develop until the moment of the ovulation.

Embryos collect.
The embryos are collected from a uterine flushing. Thus, a transcervical catheter is located into the uterus, and is proceeded the perfusion of the collect medium. The collected material is filtered and the embryos are classified in the proper farm by a veterinarian of the technical team of BIO, immediately after the collection. From now on, the embryos have two distinct destinations, the fresh transference for recipients or the cryopreservation (freezing).

Embryos transfer.
For the transference of the collected embryos, is evaluated the reproductive status of the recipient cows, and only after considered able, they will receive the embryos. The transference of the embryos is made by an enabled veterinarian, through a non-surgical method, and the embryos are deposited into the light of the uterine horn.

Embryos cryopreservation (freezing).
The cryopreservations procedures are carried out in the proper farm by a veterinarian of the technical team of BIO. These embryos are stored in liquid nitrogen tanks at -196ºC, for an indeterminate period. Conceptually, the freezing of embryos is possible through dehydration of the embryonic cells promoted by the passing of embryos in hyperosmotic solutions, called cryoprotectives (glycerol, ethylene-glycol, among others). Once individually packed in vanes and identified, the dehydrated embryos are slowly cooled until reaching the temperature of -32,5ºC. After reaching this temperature, the pallets are immersed in liquid nitrogen and transferred to nitrogen tank of the proper farm.