the primary goal of every cow-calf producer is to raise as many superior calves as possible accomplishing this goal has been difficult however because superior cows could have only one calf per year with the development of embryo transfer it is now possible to have several calves from the same cow in one calf crop embryo transfer is the removal of early developing embryos from a donor female and replacement of these embryos into the reproductive tracts of suitable recipients for gestation and parturition embryo transfer allows the cattle producer or rancher to make better use of superior females this process dramatically increases the number of offspring that can be produced by these females the average cow is able to produce approximately seven to ten calves in her lifetime the number of viable embryos that she could produce is far greater than that however because of the length of gestation 283 days she can only produce one calf per year through super ovulation and embryo transfer the number of calves she can produce can be increased significantly by removing embryos early in development and placing these embryos into suitable recipients these females are able to produce many more offspring than their lifetime would allow through natural breeding if a cow is super ovulated repeatedly she may be able to produce as many as 30 embryos per year however the sensitivity to super ovulation treatment may be greatly reduced after three consecutive cycles if the cow is allowed to rest for two or three months or is allowed to carry a pregnancy to term she will be resynthesized to the treatment most producers do not push their cows so hard because they do not want the cow to be burned out by these treatments the average cow will produce 3 to 4 calves per year through embryo transfer although this sounds like a relatively small number we must consider that this cow may be producing 30 to 40 calves in her lifetime rather than just 7 to 10 another advantage of embryo transfer is that this is a relatively fast way to produce enough offspring to progeny test females to accurately progeny test bulls they must have at least 10 offspring through natural mating this can be accomplished in one calving season for most Bulls however for cows this would take a lifetime frozen embryos are more economical to export than fully developed animals because of animal quarantine regulations designed to prevent disease spread from one country to another embryo transfer can also be used to increase the populations of rare breeds in this country producers can raise calves from these rare breeds without purchasing the breeding stock embryos may be imported from other countries or they may be the result of a mating between two of the rare peer breads already in this country this brøndby calf is a good example there are very few pure bromby cattle in the United States at this time so most purebred brøndby calves are the result of embryo transfer this is an example of a Brahman calf that was born to a Hereford cow and a Hereford calf that was transferred to a Brahman cow the foster mother has no genetic effect on the calf but will influence the calf's weaning weight through her own milking ability because of the cost of this procedure mainly producers of purebred animals can justify its use just as artificial insemination was once available only to a select few use of embryo transfer has been somewhat limited now artificial insemination is available to all cattlemen that wish to take advantage of it perhaps one day embryo transfer will be utilized by commercial breeders as well as seed stock producers before selecting the cattle for this procedure the producer should study sire summaries EPDs and other performance records available to him these records will indicate which animals have the genetic merit necessary to become a part of an embryo transfer program the donor cow should have high genetic merit so that when the number of her offspring is increased the production average of the herd increased as well the sire should also have high genetic merit and should pass a breeding soundness evaluation if the producer is using natural service breeding this evaluation will determine if he is fertile enough to be used as a herd sire the evaluation includes determination of structural soundness a blood test scrotal circumference measurement and semen evaluation the recipient cows should not be expensive or prized animals however they should be sound fertile good mothers and have good dispositions they should also have good milking ability so that the calves they raise will be able to meet their full pre weaning growth potential here are some terms and definitions related to embryo transfer you should be familiar with estrus the period of time when the female is receptive to breeding and is able to conceive it usually lasts 6 to 14 hours and occurs approximately every 21 days in the cow estrus cycle the regular pattern of changes a body goes through from one estrus to the next approximately 21 days in length in the cow it may be interrupted by pregnancy or manipulated through hormone treatment gametes male or female germ cells egg or sperm conceptus the fertilized egg embryo or fetus gestation carrying of the young in the uterus or pregnancy parturition the act or process of giving birth to the offspring the first step in the collection process is to induce super ovulation in the donor cow during normal operation only one egg is released by the ovary super ovulation is achieved with synchronized injections of FSH or follicle stimulating hormone this hormone stimulates each ovary to release as many as seven or more eggs 12 hours after standing estrus the donor cow is artificially inseminated due to the large number of eggs to be fertilized two straws of semen are used only one straw would be used in a typical a I situation then seven days after estrus the donor cow is flushed and the embryos are collected dr. Clifford Dorn of rafter de genetics has been performing embryo transfers for thirteen years and will demonstrate and discuss the procedure we begin the embryo collection process by administering the epidural anesthesia locating the junction between the sacrum and the first sacral vertebra we can inject the lidocaine or the anther cane into the vertebral fossa we elevate the tail for just a few seconds to ensure that the liquid stays within the fossa this anesthesia will act to knock out the rectal contractions and to actually dead in the reproductive tract we now palpate the animal and wash off the vulva and perennial region with water once we have thoroughly washed the area we will use a paper towel to soak up any excess fluid now the assistant will hand me the catheter spread the vulva so that we can actually enter into the vagina without contaminating the catheter then using rectal palpation we will renew plate the cervix and slowly pass the catheter through the cervix into the body of the uterus once we get into the uterus we need to slide the catheter all the way up into one uterine horn the technician will assist me by inflating the balloon with air once the balloon is inflated that channel is clamped with the pair of hemostats the stylet can then be removed the stylet is placed back into the sterile bag so that can be used when we place the catheter into the second uterine horn now the assistant will attach the tubing the white Junction the tubing fits right into the backside of the Foley catheter we now have a completely closed system it's important that all the faeces be removed from the rectum in order to assure ease of palpation at this point the inlet is open and the fluid is flowing into the right uterine horn now we will clamp off the inflow and open the outflow the fluid will then travel down the outflow tube and enter the embryo filter as the fluid begins to fill the embryo filter the technician can open the clamp on the bottom of the filter and allow it to drain off as the fluid drains down there's a filter screen across the bottom of this cup which prevents the embryos from traveling out it's important that we maintain a level of fluid in the filter we do not want the filter to run dry we do not want it to overflow as the fluid is flowing into the embryo filter we will use rectal palpation to massage the tip of the uterine horn the embryos are out near the junction between the uterus and the oviduct itself once the fluid exits the uterus we will clamp the outflow open the inflow and allow fluid to flow back in note that the bag of fluid is elevated above the animals back so that we can use gravity flow to infuse the uterus once it's filled we clamp open the outflow and again massage the fluid back out this procedure is repeated several times until approximately 500 milliliters of solution has been washed through the uterus this volume is usually sufficient to ensure that all of the embryos have been recovered after we complete flushing on the right year and horn the tubing will be removed kept back off the air will be removed from the balloon and a catheter will be retracted from the reproductive tract care should be taken that sterility of the catheter is maintained at all times the stylet is clamped back into position and the catheter when the catheters reinserted into the uterus this time we were slide the catheter up into the left uterine horn in approximately the same position as we did for the right side the same procedure now follows when the procedure is complete and both horns are effectively flushed the catheter is then removed and the fluid is drained back through the tubing a small amount of fluid is then flushed from the bag through the tubing to help rinse out any fluid that's left in the tubing at this point the embryo filter can be removed and taken into the laboratory washed into a dish and then the embryos can be identified once in the laboratory the embryo filter needs to be removed from the tubes we then drain this fluid off the bottom until we have an extremely low level of fluid left in the filter the top is then removed we carefully rinse off the filter screen it is very important that a firm stream of solution is used to rinse the filter removing all of the debris and mucus which may be attached to the filter the dish can now be placed on the microscope and searched for the embryos we use a dissecting microscope to identify the embryos the searching objective is usually around 10x magnification using the holding solution which we prepared earlier we will now fill up a 6 weld dish by inserting the solution through the sterile filter we then identify the lid of the dish with the qaol number using a sterile you know pet we would slowly move the air bubbles out of our view and then we would begin searching for the embryos once we have the embryos identified for transfer we can wash them in the six-wheeled dish and then load them individually in the quarter CC straws the embryos are loaded into the quarter CC straws in three bands the first man strictly contains solution the second band contains the embryo and the final band contains another small amount of solution once we have all of the embryos loaded into the straws we can place the straws back into a sterile bag for transport now we're going to cover the embryo freezing process checking on record we see that we have a number of embryos ready to freeze the freezing solution we use is a 10% glycerol solution we would draw up approximately two to three mils of the 10% glycerol solution using an airtight syringe we need to filter the solution into the four weld dish all four wells of this particular dish will contain the same solution the 10% glycerol the filter acts to sterilize the solution once we have the solution in the dish we need to label the dish showing that it does contain the glycerol our next step is to label the straws this is a very tedious part of the entire procedure so we need to do it before we actually start working with the embryos in this case we only have three straws to label we begin with the breed code of the particular animal then the animals registration number followed by the straw number all of the writing needs to be done on the cotton plug into the straw and on the back side wipe the embryo freeze code which identifies the particular company doing the freezing followed by the date with this information we can check back up on the records and determine exactly which embryo is frozen and each straw now that the straws are ready we can actually begin working with the embryos the embryos are handled using a sterile Yoona pet the inter pet is attached onto the end of a syringe which has a small piece of rubber tubing attached by exerting pressure on the rubber tubing we can call suction and apply pressure to move the embryos by moving a small volume of fluid within that glass capillary tube now we will select the embryos that we want to freeze put them into the second well and slowly wash them once we've washed them we put them into the third well and wash them again this will act to remove any debris that we have from the collection dish that we used now we place the embryos into another dish that contains more of the actual collection solution once we go into the first will we're going to wash the embryos then we're going to slowly move them down through each succeeding will each whale contains the exact same sterile solution we will wash the embryos approximately 10 times this will ensure that we are not moving any debris from the collection solution and it also helps in the prevention of disease transmission once the embryos have completed the washing stage we need to set our timer for 15 minutes they washed embryos can then move back into the unit pet then using the glycerol dish place the embryos into well number one this begins the dehydration process we start our 15-minute timer slowly wash the embryos around in well number one assuring that we're getting a good mix of the solution that we added to it and pick up the embryos move them into well number two once in well number two we again wash the embryos pick up the embryos and move them into well number three well number three is the final well which we replace the embryos we then take our labeled straws starting with what straw number one and attach it to the 1cc tuberculin syringe we now go into well number four to draw up the first bandit solution then a small air band go into well number three and slowly pick up an embryo once we get the embryo a small air band and a final band out of well number four we use well number four for the first and the last band so that we're sure that we do not accidentally draw up a second embryo we then follow the same procedure on each embryo once the embryos have been loaded into the straw we need to sell each straw using a heat sealer the heat sealer are actually buying the end of the straw by melting it the tip of the straw is placed against the heat sealer pressure is applied and the heat will actually seal the straw both ends of the straw need to be sealed only the extreme tip of the straw needs to extend across the heating element this is a properly sealed straw once the straws are sealed they can be placed near the freezer and wait for the 15 minute timer to go off the embryo program needs to be checked the initial temperature is negative seven degrees centigrade it can be adjusted by rotating the knob counterclockwise or back clockwise to get to the desired temperature the holding temperature will be negative 36 degrees centigrade the rate will be zero point three degrees centigrade per minute while we are waiting for the embryos to equilibrate in the glycerol solution it's a good time to update your records a freezing record needs to be filled out for each group of embryos identifying the particular donor and sire used the date of freezing and each individual embryo as far as which straw is placed in the records are very important aspect of the embryo collection procedure proper records are the key to a successful program while the freezer is cooling we need to place a brass rod into a liquid nitrogen tank in order to seed or induce ice crystals in the embryos once the program reaches negative seven degrees centigrade it's ready to place the embryos into the freezing unit the embryos need to be placed down into the alcohol bath in an upright position with the cotton plug extending above the level of the alcohol yes we're sure that the writing does not become washed off in the liquid once the embryo straws have been in the freezer for two to three minutes we need to induce ice crystal formation using the frozen brass rod care should be taken to hold the rod with a paper towel so that you do not burn yourself each straw needs to be raised individually touch the band containing the embryo and the band above it if you notice a small bit of ice crystals will form this is what we call seeding once the embryos have been seeded we need to replace the lid and wait for another two to three minutes before we start the program after two to three minutes each umbria needs to be checked to ensure that ice crystals have formed since we have proper ice crystal formation we can now start the embryo program by depressing the run button this will initiate the program and cool down from negative 7 to negative 36 degrees centigrade now we need to label the Canes for the freezing process on the goblet itself we need to put the same type of information we have on the straw here we have the breed code in this case is Simmental the registration number of the donor animal followed by the animals actual number we then put the freeze code of the company followed by the date the same information needs to be written on the neck of the cane so we go near the top portion once again put the breed code registration number and the donors private herd number we didn't put the iet s freeze code for our company and the date you