title: Resumption of postpartum ovarian cyclicity in high-producing Holstein cows.
abstract: The objective of this study was to investigate the resumption of ovarian cyclicity postpartum in high-producing dairy cows in commercial dairy farms under subtropical conditions. The cows were kept in a free-stall or tie-stall barn. Milk samples were collected from cows twice weekly, and progesterone in the skim milk was assayed by double-antibody ELISA. Cows were examined rectally and vaginoscopically at 2-week intervals after calving. Body condition score (BCS) and body weights were taken before and after calving. A cow was considered to have resumed ovarian cyclicity on the day of ovulation if followed by regular ovarian cycles. Thirty seven percent (n=20/54) of the cows had normal resumption of ovarian cyclicity (resumption within 45 days after calving), and 63% (n=34/54) had delayed resumption (resumption did not occur until >45 days after calving). Delayed resumption Type I (one or more ovarian cycles with luteal phase >20 days, i.e. prolonged luteal phase; 31.5%) and delayed resumption Type II (first ovulation did not occur until > or =45 days after calving, i.e. delayed first ovulation; 24.1%) were the most common types of delayed resumptions. Almost half (46.3%) of the cows did not resume their ovarian cyclicity until >65 days postpartum. Cows with delayed resumption Type I had a higher incidence of abnormal cervico-vaginal discharge (64.7%) and incomplete uterine involution (94.1%) compared to cows with normal resumption (P<0.01). The BCS of cows with delayed resumption Type II were lower than those of normal resumption cows at 5 weeks and later in the postpartum period (P<0.05). Approximately two-thirds of high-producing cows had delayed resumption of ovarian cyclicity postpartum. Prolonged luteal phase and delayed first ovulation were two important ovarian dysfunctions that delayed postpartum resumption of cyclicity in high-producing dairy cows.
authors.affiliation: Animal Science Laboratory, Graduate School for International Development and Cooperation (IDEC), Hiroshima University, 1-5-1 Kagamiyama, Higashi-Hiroshima 739-8529, Japan.
authors.forename: Hemanta Kumar
authors.initials: HK
authors.lastname: Shrestha
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nakao
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Higaki
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Suzuki
authors.forename: Masashi
authors.initials: M
authors.lastname: Akita
mesh_terms: D000818:Animals; D001823:Body Composition; D001835:Body Weight; D002417:Cattle / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D030762:Estrous Cycle; D005260:Female; D007564:Japan; D007774:Lactation; D008892:Milk / Q000737:chemistry; D010060:Ovulation; D049590:Postpartum Period; D011374:Progesterone / Q000032:analysis; D012098:Reproduction; D013997:Time Factors
chemical_list: D011374:Progesterone