title: Effect of the administration of GnRH or hCG on time of ovulation and the onset of estrus-to-ovulation interval in sows in Thailand.
abstract: The aim of the present study was to evaluate the control of ovulation by the administration of human chorionic gonadotropin (hCG) or gonadotropin-releasing hormone (GnRH) at the onset of estrus. Thirty-three multiparous sows housed under tropical conditions and showing standing estrus within 5 days after weaning were included. The sows were allocated to three groups, spontaneous ovulation (control group, n = 10), induced ovulation using 750 IU hCG (hCG group, n = 10), and induced ovulation using 50 μg GnRH (GnRH group, n = 13). The hormones were given at the onset of estrus and the occurrence of ovulation was monitored every 6 h by transrectal ultrasonography. Data for weaning-to-estrus interval, onset of estrus-to-ovulation interval (EOI), and the length of estrus were recorded. All sows in the control and hCG groups ovulated, while 3 out of 13 sows treated with GnRH developed cystic ovaries (did not ovulate). Of those sows ovulating, the EOI of the hCG (40.2 ± 1.7 h) and GnRH (37.5 ± 3.3 h) groups were shorter than that of the control group (63.6 ± 9.6 h; P < 0.05). In conclusion, the administration of either hCG or GnRH at the onset of estrus can control time of ovulation but, at the dose employed, sows receiving GnRH may develop ovarian cysts.
authors: Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 10330, Thailand.
authors: Kittiwat
authors: K
authors: Wongkaweewit
authors: Puchong
authors: P
authors: Prommachart
authors: Rattawat
authors: R
authors: Raksasub
authors: Kakanang
authors: K
authors: Buranaamnuay
authors: Mongkol
authors: M
authors: Techakumphu
authors: Fabio
authors: F
authors: De Rensis
authors: Padet
authors: P
authors: Tummaruk
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000008:administration & dosage*; D004971:Estrus / Q000502:physiology*; D004972:Estrus Detection; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage*; D018869:Heat-Shock Response; D006801:Humans; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000254:growth & development; D010060:Ovulation / Q000187:drug effects*; D010061:Ovulation Detection; D010062:Ovulation Induction; D034421:Sus scrofa / Q000502:physiology*; D013997:Time Factors; D014463:Ultrasonography; D014886:Weaning
chemical_list: D006063:Chorionic Gonadotropin; D007987:Gonadotropin-Releasing Hormone