title: Milk progesterone profile at and after artificial insemination in repeat-breeding cows: effects on conception rate and embryonic death.
abstract: The aim of this study was to investigate whether the skim milk progesterone concentrations at artificial insemination (AI) and day of rise of post-ovulatory progesterone concentration thereafter affect the conception and embryonic death rates in repeat-breeding cows. Milk samples were obtained from 96 repeat-breeding cows that failed to conceive to three or more AIs. The samples were taken from the cows at the day of AI and three times/week until day 45 post-AI. Skim milk was obtained after centrifugation and used for progesterone assay. The cows with a progesterone concentration more than 0.5 ng/ml at AI showed a significantly higher incidence of late embryonic death than those having a progesterone concentration<0.5 ng/ml at AI (p<0.01). As the progesterone level at insemination rose, conception rate declined. A negative correlation was shown between conception rate and skim milk progesterone level at AI. Of 56 cows showing a rise of progesterone to 1 ng/ml or more within 6 days after AI, 28 cows (50%) conceived. On the contrary, only eight of 39 cows (20.5%) conceived when the progesterone rose up to 1 ng/ml after day 6 post-AI. We concluded that increased progesterone concentration at the time of AI and delayed rise of progesterone post-AI might lead to decrease in fertility in repeat-breeding cows.
authors.affiliation: Animal Science Laboratory, Graduate School for International Development and Cooperation, Hiroshima University, Higashi-Hiroshima, Japan.
authors.forename: M E
authors.initials: ME
authors.lastname: Ghanem
authors.forename: T
authors.initials: T
authors.lastname: Nakao
authors.forename: K
authors.initials: K
authors.lastname: Nakatani
authors.forename: M
authors.initials: M
authors.lastname: Akita
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D001947:Breeding; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D005260:Female; D005298:Fertility / Q000502:physiology*; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary*; D008892:Milk / Q000737:chemistry*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000662:veterinary; D018873:Pregnancy Rate; D011374:Progesterone / Q000032:analysis*
chemical_list: D011374:Progesterone