title: Repeatability of antral follicle counts and anti-Müllerian hormone and their associations determined at an unknown stage of follicular growth and an expected day of follicular wave emergence in dairy cows.
abstract: The objectives were to determine (1) the repeatability of antral follicle counts (AFC) and anti-Müllerian hormone (AMH) concentrations at an unknown stage of follicular growth (FG) and at an expected day of follicular wave emergence (FWE) in dairy cows, and (2) the association between AFC and AMH at the above two stages. Transrectal ultrasound imaging of the ovaries and blood sample collection were performed on 91 lactating Holstein cows (33 primiparous, 58 multiparous) to determine AFC and serum concentrations of AMH at an unknown stage of FG (mean ± SEM; 14 ± 0.5 d postpartum) and an expected day of FWE (mean ± SEM; 73 ± 0.5 d postpartum, approximately 36 h after the 2nd GnRH of Ovsynch protocol). The AFC ranged from 10 to 53 (mean ± SEM; 26.1 ± 1.0) and 6 to 45 (mean ± SEM; 23.4 ± 1.0) at an unknown stage of FG and expected day of FWE, respectively (P = 0.02). Serum concentrations (pg/mL) of AMH ranged from 13.9 to 528.8 (mean ± SEM; 187.3 ± 13.1) and 38.2 to 774.1 (mean ± SEM; 218.7 ± 14.5) at an unknown stage of FG and expected day of FWE, respectively (P < 0.01). The repeatability estimates for AFC and serum AMH concentrations between an unknown stage of FG and the expected day of FWE were 0.37 and 0.73 (P < 0.01), respectively. The correlation between AFC and AMH was moderate at an unknown stage of FG (r = 0.54; P < 0.01) and at an expected day of FWE (r = 0.59; P < 0.01). In summary, both AFC and AMH were repeatable when measured at an unknown stage of FG and an expected day of FWE, but the repeatability was greater for AMH. Thus, if cows are tested at an unknown stage of FG, serum AMH may be a more reliable phenotype than AFC to test association with reproductive outcomes. Furthermore, AFC and AMH were moderately correlated at the two stages examined.
authors.affiliation: Department of Agricultural Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Gobikrushanth
authors.affiliation: Department of Agricultural Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
authors.forename: P A
authors.initials: PA
authors.lastname: Dutra
authors.affiliation: Department of Agricultural Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
authors.forename: T C
authors.initials: TC
authors.lastname: Bruinjé
authors.affiliation: Livestock Research and Extension Branch, Alberta Agriculture and Forestry, Edmonton, AB T6H 5T6, Canada.
authors.forename: M G
authors.initials: MG
authors.lastname: Colazo
authors.affiliation: Teagasc, Animal & Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland.
authors.forename: S T
authors.initials: ST
authors.lastname: Butler
authors.affiliation: Department of Agricultural Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada; Livestock Research and Extension Branch, Alberta Agriculture and Forestry, Edmonton, AB T6H 5T6, Canada. Electronic address: divakar.ambrose@gov.ab.ca.
authors.forename: D J
authors.initials: DJ
authors.lastname: Ambrose
mesh_terms: D000818:Animals; D054304:Anti-Mullerian Hormone / Q000097:blood*; D002417:Cattle / Q000097:blood / Q000502:physiology*; D005260:Female; D006080:Ovarian Follicle / Q000502:physiology*; D010060:Ovulation / Q000097:blood / Q000502:physiology*
chemical_list: D054304:Anti-Mullerian Hormone
keywords: Characterization; Fertility; Ovarian ultrasonography; Reproductive phenotypes