Effect of eCG or eCG Plus hCG on Oestrus Expression and Ovulation in Prepubertal Gilts

Manjarín, Rodrigo; Cassar, Glen; Sprecher, D.J.; Friendship, R. M.; Jc, Dominguez; Kirkwood, R. N.

doi:10.1111/j.1439-0531.2008.01089.x

Cited by 14 publications

(11 citation statements)

References 13 publications

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“…The present results also support our previous findings (Manjarin et al. 2008a,b) and literature evidence (Gama et al.…”

Section: Discussionsupporting

confidence: 94%

“…Gonadotrophic preparations used to stimulate oestrus in gilts are equine chorionic gonadotrophin (eCG) and combinations of eCG with human chorionic gonadotrophin (hCG). We have previously confirmed that, compared to treatment with 600 IU eCG alone, oestrus and ovulation responses of gilts were improved when injected with 400 IU eCG combined with 200 IU hCG (PG600 ® ; Intervet International, Boxmeer, The Netherlands) (Manjarin et al. 2008a).…”

Section: Introductionmentioning

confidence: 79%

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Effect of hCG Treatment on the Oestrous and Ovulation Responses to FSH in Prepubertal Gilts

Manjarín¹,

Jc²,

Castro³

et al. 2009

Reprod Domestic Animals

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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 x 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.

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“…The present results also support our previous findings (Manjarin et al. 2008a,b) and literature evidence (Gama et al.…”

Section: Discussionsupporting

confidence: 94%

Section: Introductionmentioning

confidence: 79%

Effect of hCG Treatment on the Oestrous and Ovulation Responses to FSH in Prepubertal Gilts

Manjarín¹,

Jc²,

Castro³

et al. 2009

Reprod Domestic Animals

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“…In the present study, 67.5% of gonadotrophin‐treated gilts exhibited oestrus by 7 days after injection, which is consistent with previous reports (Kirkwood ; Manjarin et al. ,b), while only 5.7% of the control gilt population was pubertal by 7 days after the start of boar exposure. Results from this study show that PG600 ® treatment at 154 days of age induced oestrus; however, at breeding, a greater proportion of control gilts had been observed to have experienced at least three oestrous periods.…”

Section: Discussionsupporting

confidence: 93%

“…When PG600 ® is injected into pre‐pubertal gilts, experience has shown that up to 30% of the gilts do not show behavioural oestrus within 10 days (Kirkwood ; Manjarin et al. ,b) and, based on blood progesterone levels 10–14 days after treatment, approximately 65% (Manjarin et al. ) to almost 100% (Tilton et al.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Gonadotrophin‐Induced First Oestrus on Gilt Fertility

Hidalgo

Friendship

Greiner

et al. 2014

Reprod Domestic Animals

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Contents The aim of this study was to determine the association between the oestrous response of pre‐pubertal gilts to gonadotrophin injection or boar exposure and their subsequent farrowing rate and litter size. At 154 days of age, randomly selected pre‐pubertal gilts received an intramuscular injection of 400 IU equine chorionic gonadotrophin plus 200 IU human chorionic gonadotrophin (PG600®; Merck Animal Health; n = 181). From the remaining pool of animals not treated with hormones, the first gilts showing signs of oestrus were selected to act as controls (n = 201). Boar exposure began at 155 days of age for both groups, and gilts were bred at a weight of approximately 130 kg. Comparisons were made between PG600®‐treated gilts exhibiting oestrus or not within 7 days post‐injection (early and late responders, respectively) and control gilts exhibiting oestrus or not within 30 days after beginning of boar exposure (select and non‐select control gilts, respectively). By 162 days, oestrus was detected in 67.5% of PG600®‐treated gilts compared with 5.7% of control gilts (p < 0.0001). The proportion of animals observed in oestrus at least three times before breeding was greater for select control gilts compared with early and late responder PG600®‐treated gilts (p ≤ 0.001). There were no significant differences in farrowing rate and litter size between the four treatment groups. These data indicate that PG600® is an effective tool to induce an earlier oestrus in gilts, that subsequent farrowing rate and born alive litter size compare favourably to that of select gilts and that gilts failing to respond promptly to hormonal stimulation do not exhibit compromised fertility.

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