Comparison of 5-day versus 7-day PRID®Delta CO-Synch protocols in beef cattle

The main advantage of timed artificial insemination (TAI) protocols is that they allow artificial insemination without the need for heat detection. CO-Synch programs are the type of TAI programs where second dose of GnRH is injected concurrently at the time of TAI. However, literature of CO-Synch programs from tropical regions of the world is unavailable. The objectives of this study were to compare 5-day CO-Synch (5DCOS) and 7-day CO-Synch (7DCOS) plus progesterone-releasing intravaginal device (PRID®Delta) in terms of estrus response rate (ERR), electrical resistance of vaginal mucus (ERVM), and progesterone (P4) profile in beef cattle. A total of 26 Brangus-cross cattle (18 postpartum cows and 8 heifers) were randomly assigned to two groups to receive either the 5DCOS or 7DCOS protocol. Animals in both treatment groups received P4 device and GnRH on days D-7 and D-5, respectively for 7DCOS and 5DCOS. On day 0 (device removal), cattle in 7DCOS received a single dose of prostaglandin (PGF2⍺), while cattle in 5DCOS received two doses 8 hours apart (initial dose upon device removal). The second dose of GnRH was injected at the scheduled TAI; 58 and 72 hours after PGF2⍺. The result showed ERR was proportionally higher in cows in 7DCOS than 5DCOS, but the difference was not significant (80 vs. 37.5%, p > 0.05). Likewise, the ERR in heifers was not significantly different (75 vs. 50%, p > 0.05). No significant differences were observed in EVRM across days in both cows and heifers, and also ERVM failed to distinguish cattle in estrus and non-estrus. P4 concentration was relatively constant throughout the treatment period in both cows and heifers (p > 0.05). 7DCOS in cows and 5DCOS in heifers observed comparatively high P4 values, but the differences between days were not significant (p > 0.05). In conclusion, both protocols effectively induced estrus response in both cows and heifers and maintained a consistently high circulating P4. However, ERVM was not effective in identifying cattle in estrus in a TAI program.

Text FPV 2025 2 - Full Text.pdf Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (2MB) Text FPV 2025 2.pdf Restricted to Repository staff only Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (3MB)

Actions (login required)

View Item