There are two major criteria for the selection of donor animals, genetic merit and reproductive performance. The buffalo breeder bases his selection on the performance of the potential donor itself, e.g. its milk production records or the performance of its previous offspring.
Criteria applied by the owner do not automatically make the potential donor a good prospect for embryo transfer. The donor buffalo must be in good body condition and preferably gaining weight. It should be free from underlying diseases, a minimum of 50–60 days post-partum and cycling regularly. Generally, buffaloes with a history of reproductive problems will not make good donor animals.
Donors are further evaluated by rectal examination of the cervix, uterus and ovaries to determine that they are free from adhesions or other palpable lesions. It is prudent to test the patency of the cervical canal with a cervical dilator for a sufficient diameter to permit passage of a collection catheter. This prevents the occasional frustration of being unable to negotiate the cervix after a series of costly hormonal injections, particularly in nulliparous animals.
Vaccinations against local diseases should be current.
Blood typing of both donor and sire prior to or at the time of embryo transfer for subsequent identification of offspring is highly recommended and may be required prior to export.
Accurate oestrus detection methods are also intensified.