Effect of the administration of GnRH or hCG on time of ovulation and the onset of estrus-to-ovulation interval in sows in Thailand |
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Authors: | Kittiwat Wongkaweewit Puchong Prommachart Rattawat Raksasub Kakanang Buranaamnuay Mongkol Techakumphu Fabio De Rensis Padet Tummaruk |
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Institution: | (1) Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 10330, Thailand;(2) Department of Obstetrics, Gynaecology and Reproduction, Faculty of Veterinary Science, Chulalongkorn University, Pathumwan, Bangkok, 10330, Thailand;(3) Department of Animal Health, University of Parma, Parma, Italy; |
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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. |
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