Development of estrous synchronization protocols using melengestrol acetate in Bos indicus cattle

Area of Science:

• Veterinary Science
• Animal Reproduction
• Beef Cattle Production

Background:

• Bos indicus cattle often experience anestrus postpartum, impacting reproductive efficiency.
• Estrus synchronization protocols are crucial for improving pregnancy rates in commercial cattle operations.
• Managing postpartum body condition and preventing premature luteolysis are key challenges in cattle reproduction.

Purpose of the Study:

• To develop an effective estrus synchronization protocol for Bos indicus cattle using melengestrol acetate (MGA).
• To induce estrous cyclicity in anestrous cows before postpartum body condition loss.
• To increase the likelihood of early postpartum pregnancy through synchronized estrus and natural service.

Main Methods:

• Five experiments were conducted on commercial farms in Brazil.
• A protocol involving MGA (0.5 mg/d for 14 days), estradiol cypionate (2.0 mg IM), temporary weaning (48 hours), and natural service was developed.
• Estrus cyclicity, synchronization, and pregnancy rates were monitored.

Main Results:

• The developed protocol effectively induced estrous cyclicity in anestrous cows.
• Estrus activity was synchronized, and premature luteolysis was prevented.
• The treatment showed no negative effect on pregnancy rates.

Conclusions:

• The MGA-based estrus synchronization protocol is effective for Bos indicus cattle.
• This protocol addresses key challenges in postpartum cattle reproduction, including anestrus and luteolysis.
• The findings support the use of this protocol to improve reproductive efficiency and early pregnancy in beef herds.