Abstract #T208
Section: Reproduction (posters)
Session: Reproduction II
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Exhibit Hall A
Session: Reproduction II
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Exhibit Hall A
# T208
One injection of high-concentration prostaglandin F2α is as effective as two injections of conventional prostaglandin F2α in causing luteolysis for dairy cows subjected to a 5-d CIDR-Cosynch protocol.
J. A. Spencer*1, K. Carnahan1, W. J. Price2, B. Shafii2, A. Ahmadzadeh1, 1Animal and Veterinary Science, University of Idaho, Moscow, ID, 2Statistical Program, University of Idaho, Moscow, ID.
Key Words: prostaglandin F2α dose, luteolysis, dairy cow
One injection of high-concentration prostaglandin F2α is as effective as two injections of conventional prostaglandin F2α in causing luteolysis for dairy cows subjected to a 5-d CIDR-Cosynch protocol.
J. A. Spencer*1, K. Carnahan1, W. J. Price2, B. Shafii2, A. Ahmadzadeh1, 1Animal and Veterinary Science, University of Idaho, Moscow, ID, 2Statistical Program, University of Idaho, Moscow, ID.
The objective of this study was to examine the effects of 1 or 2 doses of prostaglandin F2α (PG, dinoprost tromethamine), or one dose of high-concentration formula PG (HighCon) on progesterone (P4) concentration profiles, and luteolysis (P4 < 0.5 ng/mL) in lactating dairy cows subjected to a 5-d CIDR-Cosynch protocol. On d 0, 67 cows received GnRH, and a CIDR was inserted. On d 5, CIDR was removed and cows were assigned randomly to receive one dose (5 mL) PG (1PG; 5mg/mL; n = 24), 2 doses (5 mL/dose) PG 12 h apart (2PG; 5mg/mL; n = 22), or one dose (2 mL) HighCon (12.5mg/mL; n = 21). After CIDR removal (d 5), blood samples were collected every 12 h from d 5 to 8 to measure P4. On d 8, all cows received a second GnRH and were inseminated. Ovaries were examined by ultrasonography on d 0, 5, and 8. A repeated measures analysis assuming a lognormal distribution was used to assess treatment differences in P4 concentrations. The model included terms for treatment, the repeated factor (time), and time by treatment interaction. Cow within treatment was the random effect within the model and d 5 P4 concentration was used as a covariate. All cows (n = 67) used for analysis had elevated P4 concentrations and corpora lutea before treatment (d 5). Blood P4 concentrations decreased over time in all treatments (P < 0.01). There was an effect of treatment by time interaction on P4 (P = 0.05). By 24 h after treatments, P4 concentrations were lower, and remained at a lower level (P < 0.01) throughout the experiment for 2PG and HighCon compared with 1PG. There was no difference in P4 concentrations between 2PG and HighCon at 72 h, and the P4 averages were 1.02, 0.05, and 0.22 ng/mL for 1PG, 2PG and HighCon, respectively. Proportion of cows that went through luteolysis (P4 < 0.5 ng/mL) were greater in 2PG and HighCon compared with 1PG (100, 90.4, and 54.1%, respectively). The results indicated that 1PG was not as effective as 2PG and HighCon in causing luteolysis, and that one injection of HighCon was as effective as 2PG in decreasing blood P4 and causing luteolysis by the time of AI.
Key Words: prostaglandin F2α dose, luteolysis, dairy cow
