title: Follicle size and reproductive hormone profiles during a post-weaning altrenogest treatment in primiparous sows.
abstract: This study investigated the endocrine background of follicle size changes during post-weaning altrenogest treatment. altrenogest-treated sows received a 20-mg dosage daily at 8.00 a.m. from Day -1 to Day 14 after weaning. On Day -1, only 3/13 altrenogest-treated sows showed LH pulses compared with 8/8 control sows (P=0.001). On Day 0, control sows showed a typical high frequency-low amplitude LH pattern, indicative for recruitment of oestrogenic follicles. In altrenogest-treated animals on Day 0, half of the sows showed high frequency-high amplitude pulses from 4-5h after weaning. In altrenogest-treated sows, average follicle size increased from 3.1±0.5 mm on Day 0 to 4.4±0.6mm on Day 5, then decreased to 3.7±0.5 mm on Day 7 and stabilised thereafter. FSH and oestradiol (E2) concentrations showed a distinct diurnal pattern; high at 7.00 a.m. and low at 3.00 p.m. E2 concentrations (7.00 a.m.) showed a 2.5-fold increase from Day -1 to Day 2, and subsequently a 2-fold decline to reach a plateau at Day 8. FSH concentrations reached maximum levels by Day 5 and slowly declined afterwards. In conclusion, once-daily administration of altrenogest starting one day before weaning delays the weaning-induced increase in LH pulses. Although FSH and follicle size increase until Day 5 after weaning, follicle E2 production already decreased from Day 2 after weaning. Post-weaning altrenogest treatment thus results in a follicular wave of follicles that lose oestrogenic competence at Day 2 after weaning, presumably related to the changed LH dynamics during altrenogest treatment.
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700AH,Wageningen, The Netherlands.
authors.forename: J J J
authors.initials: JJ
authors.lastname: van Leeuwen
authors.affiliation: MSD Animal Health, PO Box 50, 5830 AB, Boxmeer, The Netherlands.
authors.forename: M R T M
authors.initials: MR
authors.lastname: Martens
authors.affiliation: Elanco Animal Health, Turnhoutseweg 30, B-2340 Beerse, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Jourquin
authors.affiliation: MSD Animal Health, R&D Pharmaceuticals, BP 67131, 49071 Beaucouze, France.
authors.forename: M A
authors.initials: MA
authors.lastname: Driancourt
authors.affiliation: University Hohenheim, Institut für Tierhaltung und Tierzüchtung, Fachgebiet Tierhaltung und Leistungsphysiologie, (470A), Garbenstr. 17, 70599 Stuttgart, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Wagner
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700AH,Wageningen, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Kemp
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700AH,Wageningen, The Netherlands.
authors.forename: N M
authors.initials: NM
authors.lastname: Soede
mesh_terms: D000367:Age Factors; D000818:Animals; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D016014:Linear Models; D007986:Luteinizing Hormone / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects* / Q000502:physiology; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects*; D034421:Sus scrofa / Q000378:metabolism*; D014204:Trenbolone Acetate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: C023445:altrenogest; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D014204:Trenbolone Acetate