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Effect of hCG Treatment on the Oestrous and Ovulation Responses to FSH in Prepubertal Gilts
Author(s) -
Manjarin R,
Dominguez JC,
Castro MJ,
Sprecher DJ,
Cassar G,
Friendship RM,
Kirkwood RN
Publication year - 2009
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/j.1439-0531.2008.01103.x
Subject(s) - estrous cycle , ovulation , endocrinology , medicine , boar , hormone , follicle stimulating hormone , andrology , biology , luteinizing hormone , semen
Contents To ensure sufficient numbers of pregnant females, particularly at hotter times of the year, hormonal induction of gilt oestrus may be necessary. However, the gilt oestrus and ovulation responses to gonadotrophin treatment have often proven unpredictable. The objective of this study was to examine possible reasons for this unpredictability. Prepubertal gilts (approximately 150 days of age, n = 63) were assigned to one of three treatments: injection of 300 IU hCG (n = 15); pre‐treatment with 100 mg FSH in polyvinylpyrrolidinone administered as 2 × 50 mg injections 24 h apart, followed by 600 IU eCG at 24 h after the second FSH injection (n = 23); or FSH pre‐treatment as above followed by 300 IU hCG at 24 h after the second FSH injection (n = 25). To facilitate oestrus detection, gilts were exposed to a mature boar for 15 min daily for 7 days. Blood samples were obtained on the day of eCG or hCG injection and again 10 days later and gilt ovulation responses determined based on elevated progesterone concentrations. The oestrus responses by 7 days were 6.7%, 17.5% and 64.0% for gilts treated with hCG, FSH + eCG and FSH + hCG, respectively (p < 0.001). The oestrous gilt receiving hCG alone and one oestrous FSH + hCG gilt did not ovulate, all other oestrous gilts ovulated. A further two anoestrous FSH + eCG‐treated gilts ovulated. These data suggest that FSH pre‐treatment facilitated the development of ovarian follicles to the point where they became responsive to hCG, but had little effect on the response to eCG.