title: Pregnancy rates in lactating dairy cattle following supplementation of progesterone after artificial insemination.
abstract: Poor conception rates in highly productive lactating cattle is especially prevalent in large, intensively-managed commercial herds. One of the causative factors is sub-optimal pre-implantation embryonic development which appears to result from inadequate circulating concentrations of progesterone. In the present study, the efficacy of very modest progesterone supplementation, between Days 3.5 and 10 post-AI, on pregnancy rates was determined in a commercial herd where bovine somatotropin (bST) was used as a management tool. All lactating cattle that were deemed to be in estrus and inseminated over a 4-week period were randomly assigned to either a control group (no treatment) or CIDR-1.9g (previously used for estrous synchronization) treatment from Day 3.5 to Day 10 post-AI. Milk samples were collected four times: on the day of AI, at Day 2 or 3, at Day 4 and at Day 22 post-AI and were analyzed for progesterone content. Data from a total of 130 breedings were used in the final analysis. The CIDR treatment increased circulating concentrations of progesterone in treated animals over those of control animals on Day 4 by 0.7ng/ml (P<0.05) and increased pregnancy rate from 35% (22/63) to 48% (32/67) (P=0.068). The effect of treatment was greater in first and second lactation cows, where pregnancy rates were 33% (18/55) in controls and 51% (31/61) in treated animals (P=0.03). The results of this study indicate that the timing of onset of the progesterone influence is important for successful pregnancy outcome, particularly in first and second lactation cows.
authors: Department of Animal Science, Cornell University, Ithaca, NY 14853, USA. sandra.larson@furman.edu
authors: Sandra F
authors: SF
authors: Larson
authors: W R
authors: WR
authors: Butler
authors: W Bruce
authors: WB
authors: Currie
mesh_terms: D000818:Animals; D002417:Cattle; D003612:Dairying; D004334:Drug Administration Schedule; D004343:Drug Implants; D005260:Female; D005300:Fertility Agents, Female / Q000008:administration & dosage / Q000494:pharmacology; D013006:Growth Hormone / Q000494:pharmacology; D007315:Insemination, Artificial / Q000662:veterinary*; D007774:Lactation; D010062:Ovulation Induction; D011247:Pregnancy; D018873:Pregnancy Rate; D011374:Progesterone / Q000008:administration & dosage* / Q000494:pharmacology*
chemical_list: D004343:Drug Implants; D005300:Fertility Agents, Female; D011374:Progesterone; D013006:Growth Hormone