When an IVF program is established, the first focus goes to donors – elite female genetics that will elevate the entire herd. Clear decisions are made about how those donors will be managed, fed, stimulated, collected and monitored. Even before those oocytes from the top animals make it to the IVF lab, they are placed in media, created and tested to provide the ideal environment.
Once at the lab, care is given to prepare sperm precisely for fertilization, to handle potential embryos in clearly defined conditions, and checklists of quality control measures are rigorously upheld. The valuable embryos created are then cautiously placed in a tube to be shipped fresh or frozen in a straw and will arrive back for transfer.
When all of the excitement of the high-valued donors and great lab results are gone, it’s not uncommon for producers to think of the final piece of the equation as somehow less important, but failing on recipients once all of that time, money and effort have gone into the embryo is like fumbling on the one-yard line. We like to think of the entire process as having three steps: donors, embryo creation in the IVF lab and recipients.
Recipient selection
When selecting recipients, several studies have demonstrated that heifers have higher conception rates than cows due to less metabolic variation, no lactational stress and fewer reproductive issues. However, selecting only heifers as recipients is not always practical or economically viable. Dairymen must weigh the value of the heifer versus the additional percentage points of conception rate. If cows are used, daughter pregnancy rate (DPR) and daughter stillbirth rate (DSB) are excellent traits for ranking recipient candidates.
Just as important is nutrition. Recipients should be on a slightly increasing plane of nutrition, with body condition score targeted at 2.75 to 3.5. Overall health should also be taken into consideration. Cows should have no history of calving issues or metritis, and heifers should be pubertal and have had a reproductive health exam. Lastly, recipients must not have received any live vaccinations within six weeks of embryo transfer (ET).
Synchronization
Recipient synchronization does not need to be complicated. It can be as straightforward as a double shot of prostaglandin given 10 to 14 days apart. Recipients will come into heat within 72 hours. On the other hand, many of our clients prefer the simplicity of continuing with the normal synchronization method the dairy uses for A.I. but, instead of breeding, just holding those heats over as recipients.
Regardless of setup, recipients should have a strong heat 6.5 to 8.5 days prior to ET. Accurate heat detection is critical, and monitoring systems help correctly identify those in heat. A uterus five or nine-plus days post-heat is not a suitable environment for pregnancy creation and should not be used, rather resynched and used on the next cycle. When managing inventories, it is important to note that approximately 85% will be good candidates to receive an embryo, so synch 15% more recipients than expected embryos. A frozen inventory can be maintained to help ensure efficient recipient use.
Day of transfer
Embryos should be transferred by a skilled veterinarian or technician. Regardless of who performs the transfers, any ET program should be overseen by a veterinarian. If embryos are frozen, ensure protocols for thawing are followed precisely and temperatures of water bath, guns and warmers are set correctly and checked frequently. Aseptic technique is important at time of transfer, as dirty equipment can lower pregnancy success. Accurate records including date of estrus and technician ID should be maintained.
Pregnancy
In well-managed herds, expect conception rates of 45%+ at day 60. Avoid any stressors that may result in pregnancy loss including: changes to pens, penmates, nutritional changes, and heat or extreme cold. All of these can impact pregnancy success. Herd health is critical to maintain high conception rates. Loss after 60 days is typically associated with stress, infectious disease or micro-organisms causing a toxic environment in the uterus.
Calving
Again, keeping accurate records is critical to success, so any recipient that goes past her due date can be induced. Work with your veterinarian on induction protocols, as most result in the cow calving within 24 to 36 hours. Inducing in the morning ensures staff will be available throughout the day to assist if needed. Even if a recipient doesn’t show signs of calving, she should be induced, as overdue calves can gain 2 pounds per day. Once calves are born, navels should be dipped with antiseptic iodine immediately to prevent umbilical infections, and pen and bedding should be kept clean.
Manage your recipients like the genetic progress of your herd depends on it – because it does.
