Resynchronizing Estrus with Progesterone or Progesterone Plus Estrogen in Cows of Unknown Pregnancy Status

Abstract

Two experiments were conducted to test 2 progesterone (P4)-based treatments that were applied to lactating dairy cattle of unknown pregnancy status to resynchronize estrus of nonpregnant cows. In experiment 1, cows were assigned randomly before a timed AI (TAI) to 1) treatment with a CIDR (controlled internal drug-releasing intravaginal insert containing P4) for 7 d starting on d 13 after TAI (CIDR; n = 300) or 2) no P4 treatment (control; n = 330). Compared with controls, P4 increased the synchrony of those detected in estrus, but failed to increase the overall return rates of non-pregnant cows during the 6 d after CIDR removal (27% vs. 31%; d 20 to 26 after TAI) and did not alter synchronized conception rates (32% vs. 20%) of those inseminated. Use of P4 did not compromise pregnancies resulting from TAI compared with controls (38% vs. 42%), but increased embryo survival between d 29 and 57 after TAI (65.5% vs. 44.3%). In experiment 2, on d 13 after TAI, 196 cows were treated with a CIDR insert for 7 d. Controls received no further treatment. Remaining cows were treated with 1 of 3 estrogen regimens: 1 mg of estradiol benzoate (EB), 0.5 mg of estradiol cypionate (ECP), or 1 mg of ECP on both d 13 and 21. Only 60% of nonpregnant, estrogen-treated cows were detected in estrus between d 20 and 26, and rates of return and conception did not differ among treatments. Estrogen on d 13 did not consistently turn over the dominant follicle when given at CIDR insertion but did increase concentrations of estradiol and reduced luteal function when administered on d 13 and 21 (24 h after CIDR removal). Treatments had no negative effects on milk yield, dry matter intake, or established pregnancies. Use of P4 alone had little effect on overall rates of return to estrus or conception at the first eligible estrus in experiment 1. Combining estrogen with P4 in experiment 2 had no detrimental effects on established pregnancies or subsequent conception and failed to improve return rates beyond P4 alone.

The effect of a progesterone (P4) intravaginal device (CIDR) on resynchronisation of oestrus and embryonic loss in previously timed inseminated dairy heifers

“…In the present study, PRs for the first eligible oestrus after CIDR removal were not different on day 30 which are in agreement with the results reported by Rivera et al (2005) and Colazo et al (2006) on day 30 in dairy and beef heifers and by El-Zarkouny and Stevenson (2004) on day 29 in dairy cows. On the other hand, PRs on day 55 post TAI in the present study were numerically higher (not significant) in CGPG group than in the control which are in agreement with the results of Hanlon et al (1997) who reported a similar PR to a resynchronised oestrus in dairy heifers using CIDR device for 5 days beginning 14 or 16 days after AI.…”

Recent Advances in the Synchronization of Estrus and Ovulation in Dairy Cows

“…Variations on this basic "double" treatment regimen have been tested with Holsteins in American herds with variable results. ElZarkouny and Stevenson [27] as well as Chebel et al [21] both reported that the post-insemination use of an ivagP4 insert could reduce pregnancy loss through increased embryo survival rate from around Day 30 to Day 60 post-insemination. However, little cognisance has been given to the likely reasons for any effects, given the limited effect of the invagP4 inserts to significantly increase plasma concentrations of progesterone in large, high producing lactating Holstein cows.…”

Recent Possibilities for the Diagnosis and Pharmacological Control of Pregnancy Loss in Dairy Cow

“…The CIDR inserts increased embryo survival between days 29 and 57 post-TAI when treatment for 7 days starting on Day 13 post-TAI was performed [99]. Similarly, PRID also improved PR when used from Day 10 post-AI for 7 days [87].…”