Embryo transfer: managing recipients and donors

For an embryo transfer program to be effective, numerous factors need to be put in place to ensure success. Nutrition, estrous cycle control, donor and recipient management are all factors responsible for the success or failure in fertility for a given herd. Utilization of body condition score is a practical method to determine nutritional status of both recipients and donors. Prepartum nutrition is critical to ensure that recipient cows calve in adequate body condition to reinitiate postpartum estrous cycles early enough to respond to synchronization protocols. Estrus synchronization for embryo transfer after detected estrus or for fixed-time embryo transfer are effective methods to increase the number of calves produced by embryo transfer. In addition, resynchronization of nonpregnant females effectively ensures that a high percentage of recipients will return to estrus and are eligible for subsequent embryo transfers. Numerous additional factors need to be assessed to ensure that the herd achieves its reproductive potential. These factors include assessing the merits of nulliparous, primiparous, or multiparous cows, ensuring that facilities allow for minimal stress, and that the herd health program is well-defined and followed. Numerous shortand long-term factors contribute to donor’s production of embryos and whether or not the recipients will maintain a transferred embryo, deliver a calf without assistance, or raise and wean a healthy calf.