Factors Affecting Suitability of Surrogate Dams for Embryo Transfer in Cattle

Sixty-seven candidate dams were used to study the effect of surrogate genotype, parity, embryo transfer phase and hormone administration method on nine animal parameters. Six cattle genotypes, six parities and two hormonal methods were evaluated. In phase I, candidates were injected with 3ml of Estrumate®. Heat expression was then detected followed by two injections 12-hr apart of the same hormone. Standing heat was observed and individuals with good sized corpus luteum were used for embryo transfer (ET). In phase II and III, CRESTAR® ear implants were placed in each candidate. Implant removal was followed by Estrumate® injection. Standing heat was later observed followed by ET. Surrogate genotype influenced BCS (P