Effect of PMSG dosage on the reproductive performance of adult ewes and ewe lambs bred at a progestagen-PMSG synchronized estrus

Ainsworth, L.; Shrestha, J. N. B.

doi:10.1016/0093-691x(85)90054-8

Cited by 21 publications

(9 citation statements)

References 14 publications

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“…However, production of estrogen in response to treatment with eCG is greater in ewe lambs than in mature ewes (Quirke et al, 1981) and doses as low as 200-250 IU eCG was sufficient to improve reproductive performance in mature ewes, while a 750 IU eCG decreased fertility (Gordon, 1971;Oldham and Pearce, 1984). No difference in reproductive performance was observed in ewes treated with 250 or 500 IU eCG (Ainsworth and Shrestha, 1985), or in ewe lambs treated with 200 or 400 IU eCG (Rekik et al, 2002). Additionally, a gonadotropin mixture of 400 IU eCG and 200 IU hCG (Safranski et al, 1992;Jabbar et al, 1994;Windorski et al, 2008) did not improve fertility and resulted in lambing rates comparable to or lower than that observed in the current study.…”

Section: Discussioncontrasting

confidence: 74%

Effect of stimulation with a gonadotropin mixture on reproductive outcome in nulliparous ewes bred during seasonal anestrus and early breeding season

Knights

Redhead

D'Souza

et al. 2015

Animal Reproduction Science

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Section: Discussioncontrasting

confidence: 74%

Effect of stimulation with a gonadotropin mixture on reproductive outcome in nulliparous ewes bred during seasonal anestrus and early breeding season

Knights

Redhead

D'Souza

et al. 2015

Animal Reproduction Science

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“…However, its long-acting biological activity can cause the continual recruitment of antral follicles, resulting in a large number of non-ovulated follicles (Armstrong et al, 1983). Several studies have examined the dose response to eCG (Ainsworth and Shrestha, 1985;Smith et al, 1988;Knight et al, 1989;Zonturlu et al, 2001) and its effects on fertility of anestrous ewes (Zarkawi et al, 1999;Zeleke et al, 2005).…”

Section: Use Of Gonadotropin Co-treatments In Ewes Bred Out-of-seasonmentioning

confidence: 99%

“…The effect of dose of eCG on the fertility of ewes bred in May and January after treatment with progestogen sponges and eCG (250 IU or 500 IU) was evaluated by Ainsworth and Shrestha (1985). The overall reproductive performance of the ewes was similar at the two breeding periods.…”

Section: Use Of Gonadotropin Co-treatments In Ewes Bred Out-of-seasonmentioning

confidence: 99%

Effects of a Gonadotropin Mixture on Reproductive Success in Progesterone- Treated Non-Lactating Anestrous Ewes

D'Souza¹

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Using exogenous gonadotropins as part of an estrous induction protocol can have beneficial effects on fertility in ewes bred out-of-season. Few studies have evaluated the efficacy of P.G. 600®, a mixture of gonadotropins with FSH-like and LH-like activity, to increase fertility in anestrous ewes and, in particular, following pre-treatment with progesterone delivered via controlled internal drug releasing (CIDR) devices. The objective of this study was to evaluate the effects of P.G. 600® on reproductive success in progesterone-treated non-lactating anestrous ewes. Ewes, which had been separated from rams for at least one month prior to the beginning of the experiment, received CIDR inserts five days prior to introduction of rams. In the first experiment, ewes were assigned randomly to receive either a 3 mL injection of P.G. 600® [i.m., 240 IU equine chorionic gonadotropin (eCG) and 120 IU human chorionic gonadotropin (hCG)] at CIDR insert removal or no further treatment. In the second experiment, ewes were assigned randomly to receive either a 3 mL injection of P.G. 600® one day prior to insert removal or no further treatment. In experiment 1, incidence of estrus was significantly greater for treated ewes than control ewes, while prolificacy (number of lambs born per ewe lambing) tended to be higher in treated ewes. In experiment 2, treated ewes had significantly higher conception rates and pregnancy rates to first service and tended to have higher overall pregnancy rates than control ewes. A greater percentage of ewes lambed in the treated group than in the control group; however, prolificacy was not different between the groups. In addition, overall lambing rates in ewes treated with P.G. 600® were significantly higher than those of the control group. An injection of 3 mL of P.G. 600® (240 IU eCG and 120 IU hCG) one day prior to CIDR removal significantly increased reproductive success in progesteronetreated non-lactating anestrous ewes. Further, the gonadotropin injection was determined to be economically beneficial.

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“…A study on the effect of PMSG dosage (250 or 500 IU) on the reproductive performance of ewes mated at a FGA-sponge/PMSG synchronized estrus (155) showed that there was no effect of PMSG dosage on fertility or prolificacy of adult ewes. Reproductive performance of ewe lambs was lower than that of adult ewes and there was a strain X treatment interaction, suggesting a greater variability in response.…”

Section: Manipulation Andmentioning

confidence: 99%

Research and technology for increasing the efficiency and output of lamb production systems

Canada¹

1987

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Effect of PMSG dosage on the reproductive performance of adult ewes and ewe lambs bred at a progestagen-PMSG synchronized estrus

Cited by 21 publications

References 14 publications

Effect of stimulation with a gonadotropin mixture on reproductive outcome in nulliparous ewes bred during seasonal anestrus and early breeding season

Effect of stimulation with a gonadotropin mixture on reproductive outcome in nulliparous ewes bred during seasonal anestrus and early breeding season

Effects of a Gonadotropin Mixture on Reproductive Success in Progesterone- Treated Non-Lactating Anestrous Ewes

Research and technology for increasing the efficiency and output of lamb production systems

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