Supplementing previously treated anestrous dairy cows with progesterone does not increase first-service conception rate

• Published in: Theriogenology 2005, Vol.63 (1), p.239-245
• Main Authors: Hanlon, D.W., Davidson, P.J., Hittmann, A.R., Joe, A.K.
• Format: Article
• Language: English
• Subjects: Administration, Intravaginal; Anestrus; Animals; Breeding; Cattle - physiology; Dairy cow; Estradiol - administration & dosage; Estradiol - analogs & derivatives; estrus synchronization; Female; Fertility; Fertilization - drug effects; pregnancy rate; Progesterone; Progesterone - administration & dosage
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2004.04.008

The objective of this study was to investigate the effect of supplementing previously treated anovulatory anestrous (AA) dairy cows with progesterone delivered intra-vaginally for 7 days, commencing 4 or 5 days after insemination, on first-service conception rate. A clinical trial, involving 990 AA dairy cows in 14 dairy herds, was conducted during the 2002/2003 breeding season. On Day −8, all cows were treated with a progesterone-containing intravaginal device (Cue-Mate ®). The devices were removed on Day −2; on Day −1, all cows were given 1 mg of estradiol benzoate im. Cows in the control group ( n = 499) received no further treatments. Cows in the treatment group ( n = 491) that had been inseminated on Day 0 or 1 had a new device inserted (on Day 4 or 5), with removal of the device after 7 days. First-service conception rates for the control and treatment groups were not different (35.0% versus 36.7% respectively; P = 0.41). Furthermore, there was no difference in conception rates between cows that had devices inserted on Day 4 or 5 (31.3% versus 37.2% respectively; P = 0.45). In conclusion, supplementation of previously treated AA dairy cows with an intravaginal progesterone-releasing device for 7 days (commencing 4 or 5 days after insemination) did not significantly improve first-service conception rate.