Progesterone concentration and lambing rate of Karakul ewes treated with prostaglandin and GnRH combined with the ram effect during breeding and non-breeding seasons

Mirzaei, Abdolah; Mohebbi‐Fani, Mehdi; Omidi, Arash; Boostani, Alidad; Nazifi, Saeed; Mahmoodianfard, Hamidreza; Chahardahcherik, Marjan

doi:10.1016/j.theriogenology.2017.06.005

Cited by 14 publications

(15 citation statements)

References 23 publications

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“…These P4 are within the normal ranges encountered elsewhere worldwide. Peak P4 levels in Karakul ewes from temperate regions (Asia) during the breeding season ranged from 7.2- 15.2 ng/ml [21]. Peak P4 levels in Gaddi ewes in the temperate latitudes of India varied from 1.44 ng/ml (anoestrus) and 1.57 ng/ml (nonpregnant during the breeding season) to 5.16 ng/ml (pregnant), thus confirming that it is not unusual for P4 levels to vary widely between different breeds of sheep [22].…”

Section: Discussionmentioning

confidence: 99%

Characterization of Oestrus Cycles in Namibian Swakara and Damara Sheep through Determination of Circannual Plasma Progesterone Levels

Kandiwa

Mushonga

Madzingira

et al. 2019

Journal of Veterinary Medicine

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A year-long prospective study characterized the seasonality of oestrus cycles in primiparous, nonpregnant Swakara (n=8) and Damara (n=5) ewes through surveillance of plasma progesterone (P4) levels. During this period, Swakara and Damara groups evidently averaged 23 oestrus cycles with an average length of 17 days. Damara ewes showed greater mean peak plasma P4 levels (11.4±0.16ng/ml) than Swakara ewes (5.4±0.11ng/ml) (P<0.05). Oestrus cycles in Damara ewes showed relatively uniform plasma P4 peaks throughout the year ranging from 10.6±0.16 to 12.6±0.24ng/ml. In Swakara ewes, P4 peaks were highest in the autumn oestrus cycles (from 7.1±0.16 to 7.5±0.11ng/ml), rapidly declining through winter to 2.2±0.08ng/ml by midspring and then rapidly increasing to 4.9±0.37ng/ml at the commencement of summer, followed by a gradual increase from 5.7± to 7.1±ng/ml by the start of autumn. The annual mean area under the curve temporal progesterone measurements (AUCPM) in Damara ewes (115.9±18.6ng⁎day/ml) was greater than that in Swakara ewes (58.6±25.3ng⁎day/ml) (p<0.05). For Swakara ewes, the mean AUCPM in summer and autumn cycles (68.2±14.7 and 79.5±10.0ng⁎day/ml, respectively) were greater than those in spring and winter cycles (28.7±12.3 and 55.0±27.3ng⁎day/ml), respectively (P<0.05). There was no seasonal variation in the exposure of the Damara ewes to P4 in between seasons (P>0.05), though, however, the Damara ewes had greater P4 levels than the Swakara ewes (P<0.05). Progesterone profiles showed that Swakara ewes possessed ‘residual’ seasonality, whereas the Damara ewes were no longer seasonal. The implications of this disparity in the seasonal exposure of Swakara and Damara ewes to luteal P4 on fertility warrant further investigation.

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Section: Discussionmentioning

confidence: 99%

Characterization of Oestrus Cycles in Namibian Swakara and Damara Sheep through Determination of Circannual Plasma Progesterone Levels

Kandiwa

Mushonga

Madzingira

et al. 2019

Journal of Veterinary Medicine

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“…In another study, performed on low-seasonality Karakul ewes [20], the male effect was combined with GnRH. In that report it was concluded that the inclusion of GnRH as part of the induction protocol reduced the fertility of the ewes.…”

Section: Discussionmentioning

confidence: 99%

“…Combining the male effect with steroid-free hormonal treatments may help to improve the results of programs of induction of ovarian-activity in highly-seasonal breeds. It has been shown in Karakul ewes that the efficacy of GnRH-PGF2α protocols to induce ovarian activity in anestrous ewes can be improved by their combination with the male effect [20]. However, Karakul is a breed with an extended breeding season, so that the combination of the male effect with GnRH-PGF2α treatments remains to be studied in highly seasonal breeds.…”

Section: Introductionmentioning

confidence: 99%

Induction of fertile estrus without the use of steroid hormones in seasonally anestrous Suffolk ewes

Miguel-Cruz

Mejía-Villanueva

Zarco

2019

Asian-Australas J Anim Sci

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ObjectiveTo evaluate the efficacy of treatments based on gonadotrophin-releasing hormone (GnRH), GnRH-prostaglandin F2α (PGF2α), and/or intense exposure to novel rams to induce fertile estrus without the use of steroid hormones in seasonally anestrous Suffolk ewes.MethodsIn the first experiment, ewes were treated with one injection of GnRH, two injections of GnRH administered 7 days apart, or a sequence of GnRH-PGF2α-GnRH (GPG). In the second experiment anestrous ewes were exposed, for 36 days starting on the day of weaning, to groups of four rams of three different breeds that were alternated every day. Besides exposure to the male effect (ME), the ewes were injected with saline solution (ME group, n = 20), with GnRH (ME-GnRH group, n = 20) or with a sequence of GnRH-PGF2α-GnRH (ME-GPG group, n = 20). The rams used for male-effect were fitted with aprons to prevent mating, and ewes detected in estrus were bred to selected fertile rams. Ovarian activity was monitored by progesterone determinations in both experiments.ResultsIn the first experiment sustained induction of ovarian activity was not achieved and no ewe was detected in estrus. In the second experiment induction of sustained ovarian activity was achieved in all groups. Most of the ewes were detected in estrus, 76.7% of the ewes were mated during a 36-d breeding period and 71.7% of all the ewes became pregnant during that period. No significant differences between groups were found for any of these variables. However, estrus detection efficiency was higher in the ME-GnRH group than in the ME group (p<0.05).ConclusionAn intense male-effect, that included the continuous presence and frequent alternation of several rams of different breeds, was sufficient to induce ovarian activity and fertile estrus in Suffolk ewes during the period of deep anestrus without the use of hormones, although addition of GnRH improved the efficiency of estrus detection.

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“…Results were expressed as means±SEM. Reproductive performance (lambing rate, single lambings, twin lambings, ewes lambing at first service and ewes lambing at second service) were statistically analyzed by Chi-square analysis (Safdarian et al, 2006 andMirzaei et al, 2017). Values of probability were considered significant when less than 0.05.…”

Section: Discussionmentioning

confidence: 99%

Ovarian Activity and Reproductive Performance of Mature Ossimi Ewes as Affected by Presence of Ram

Mahmoud

Hussein

2019

Egyptian Journal of Animal Production

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Two experiments were conducted in this study to assess the role of ram effect prior to mating on ovarian follicular dynamics and reproductive performance of Ossimi ewes. In Expt. 1, fourteen Ossimi ewes 3-6 years old were used. The first group (n=7), ewes were exposed with two trained teaser rams (REG), whilst, the second group (n=7) remaining ewes were isolated of rams (CG). The number and size of all follicles ≥2 mm and corpus luteum were monitored by ultrasonography. Expt. 2, including two mating season, 70 Ossimi ewes (3-6 years old) were selected from 115 ewes in each mating season, multiparous, non-lactating and clinically healthy. The first mating season (n=70), ewes were kept in the presence with teaser rams (REG) during the estrus detection and mating for two consecutive estrous cycles (45 d). The second mating season (n=70), ewes were remaining isolated of rams (CG) except at the time for detection of estrus. Ewes were mated after detection of estrus. While, ewes return to estrus, were mated again. At lambing, birth dates and the lambs born number per each ewe were recorded. All ewes isolated of males for three months before the beginning of the experiments. There were significant (P < 0.01) increases in the small (2-2.9 mm) and medium (3-5 mm) follicles number on ovaries of ewes in REG compared to CG. Moreover, the size of maximum ovulatory follicles and subdominant follicles (next largest follicle) were larger (P <0.001) in ewes of REG compared with those of CG. In addition, the ovulation rate mean was higher (P =0.05) in the REG than that of the CG (Expt. 1). The lambing rate was higher (P <0.01) in the first mating season (REG) compared to the ewes in the second mating season (CG). At the same time, the mean number of fecundity and litter size were higher (P <0.01) in the REG compared to the CG. Moreover, twining lambing rate was higher (P <0.01) in the REG. by contrary, the percentage of single lambing was lower (P <0.01) in the first mating season (REG). The percentage of ewes lambing at first service was higher in the REG than in CG but the difference was insignificant (Expt. 2). In conclusion, these results show that, ram introduction prior to mating season increased the ovarian activity and reproductive performance after period of isolation of Ossimi ewes.

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Progesterone concentration and lambing rate of Karakul ewes treated with prostaglandin and GnRH combined with the ram effect during breeding and non-breeding seasons

Cited by 14 publications

References 23 publications

Characterization of Oestrus Cycles in Namibian Swakara and Damara Sheep through Determination of Circannual Plasma Progesterone Levels

Characterization of Oestrus Cycles in Namibian Swakara and Damara Sheep through Determination of Circannual Plasma Progesterone Levels

Induction of fertile estrus without the use of steroid hormones in seasonally anestrous Suffolk ewes

Ovarian Activity and Reproductive Performance of Mature Ossimi Ewes as Affected by Presence of Ram

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