Bovine embryo transfer recipient synchronisation and management in tropical environments

Area of Science:

• Reproductive biology
• Veterinary science
• Embryo transfer technology

Background:

• Estrus detection is a critical but often limiting factor in cattle embryo transfer (ET) programs.
• Hormonal manipulation of the estrous cycle can improve recipient management and success rates.

Purpose of the Study:

• To evaluate the efficacy of fixed-time embryo transfer (FTET) protocols in cattle.
• To compare FTET protocols with traditional estrus synchronization methods.
• To assess the impact of equine chorionic gonadotrophin (eCG) on FTET outcomes.

Main Methods:

• Utilized gonadotrophin-releasing hormone (GnRH), prostaglandin (PG) F, progesterone/progestogen (P4)-releasing devices, and estradiol in FTET protocols.
• Administered equine chorionic gonadotrophin (eCG) in conjunction with P4 and estradiol-based FTET protocols.
• Compared pregnancy rates and recipient transfer proportions between FTET and traditional PGF-based protocols.

Main Results:

• FTET protocols increased the proportion of recipients transferred and pregnancy rates compared to traditional methods.
• The addition of eCG to P4 and estradiol-based FTET protocols further improved recipient transfer rates and pregnancy outcomes.
• In Bos taurus x Bos indicus recipients, pregnancy rates correlated positively with corpus luteum (CL) diameter and number.
• FTET protocols improved recipient transfer and pregnancy rates in repeat-breeder Holstein cows compared to PGF-based synchronization.

Conclusions:

• FTET protocols effectively eliminate the need for estrus detection in cattle ET programs.
• FTET protocols optimize recipient utilization, reduce labor, and facilitate ET implementation.
• The use of eCG in FTET protocols offers a significant advantage for improving pregnancy rates in cattle.