title: Maternal plasma oestrone sulphate concentration prior to parturition in relation to birth weight of the calf in primiparous, 2-year-old, Angus heifers.
abstract: Dystocia and assisted calving in primiparous heifers are persistent problems in beef herds, and incidence increases with increasing birth weight of calves. Plasma samples taken from 33 primiparous, 2-year-old, Angus heifers 2 days prior to parturition were analysed for oestrone sulphate concentration. Additional samples taken at 4, 6, 8 and 10 days prior to parturition were analysed for 17 of these heifers. At parturition, birth weight of the calf, post-partum live weight of the heifer, assistance at calving (n=6) and status of the calf (stillborn (n=4) vs. alive) were recorded. Maternal plasma oestrone sulphate concentration was stable from 10 to 4 days prior to parturition and increased between 4 and 2 days prior to parturition for non-assisted heifers. Maternal plasma oestrone sulphate concentration did not affect the probability of assistance at calving or stillbirth.
authors.affiliation: Institute of Veterinary, Animal and Biomedical Sciences, College of Sciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand. r.hickson@massey.ac.nz
authors.forename: R E
authors.initials: RE
authors.lastname: Hickson
authors.forename: P R
authors.initials: PR
authors.lastname: Kenyon
authors.forename: N
authors.initials: N
authors.lastname: Lopez-Villalobos
authors.forename: S T
authors.initials: ST
authors.lastname: Morris
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001724:Birth Weight / Q000502:physiology*; D002417:Cattle / Q000097:blood*; D004970:Estrone / Q000031:analogs & derivatives* / Q000097:blood; D005260:Female; D036801:Parturition / Q000502:physiology*; D011247:Pregnancy; D050497:Stillbirth
chemical_list: D004970:Estrone; C017296:estrone sulfate