title: Effect of exogenous progesterone supplementation in the early luteal phase post-insemination on pregnancy per artificial insemination in Holstein-Friesian cows.
abstract: One of the main determining factors of pregnancy per artificial insemination (P/AI) is an optimum concentration of progesterone (P4) in the early luteal phase. This study examined the effects of P4 supplementation on P/AI in lactating Holstein-Friesian cows. A total of 453 cows in 8 spring-calving herds were used in the study. Following AI, cows were randomly assigned to 1 of 2 treatment groups: (1) no subsequent treatment (control; n=221); (2) insertion of a Controlled Internal Drug Release device (CIDR) from day 4 to day 9 post-estrus (supplemented; n=232). Pregnancy per AI was determined by transrectal ultrasonography at day 30 following AI. Insertion of a CIDR increased concentrations of milk P4 in supplemented cows by 4.78ng/mL between day 4 and 4.5 in comparison with a 0.55ng/mL increase in control cows. Progesterone supplementation from day 4 to 9 after AI decreased P/AI by 12 percentage points (56 vs 44%). There was a positive linear and quadratic relationship between P/AI and milk concentration of P4 on day 4 post-estrus in control cows. An optimum concentration of 2.5ng/mL on day 4 was calculated from the logistic regression curve to achieve a probability of P/AI of 65%. When both treatments groups were included in the analysis, there was no association between P/AI and concentrations of P4 on day 4. The results of the study indicate that supplementation with P4 initiated in the early luteal phase had a negative effect on P/AI in dairy cows.
authors.affiliation: Animal & Grassland Research & Innovation Centre, Teagasc, Mellows Campus, Athenry, Co. Galway, Ireland; School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: M H
authors.initials: MH
authors.lastname: Parr
authors.affiliation: School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: M A
authors.initials: MA
authors.lastname: Crowe
authors.affiliation: School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: P
authors.initials: P
authors.lastname: Lonergan
authors.affiliation: School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: A C O
authors.initials: AC
authors.lastname: Evans
authors.affiliation: Departamento de Reproducción Animal Conservación de Recursos Zoogenéticos, INIA, Madrid, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Rizos
authors.affiliation: Animal & Grassland Research & Innovation Centre, Teagasc, Mellows Campus, Athenry, Co. Galway, Ireland. Electronic address: Michael.Diskin@teagasc.ie.
authors.forename: M G
authors.initials: MG
authors.lastname: Diskin
mesh_terms: D000818:Animals; D002417:Cattle; D003692:Delayed-Action Preparations; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary*; D008183:Luteal Phase / Q000187:drug effects*; D008892:Milk / Q000737:chemistry; D011247:Pregnancy; D011374:Progesterone / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D003692:Delayed-Action Preparations; D011374:Progesterone
keywords: Artificial insemination; Cows; Pregnancy; Progesterone supplementation