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The addition of stimulation scheme with anti-esterase substances improves the ewe lambing rate

I. V. Lobachova, Institute of Animal Husbandry in Steppe Regions "Ascania-Nova" named after M. F. Ivanov's — National Scientific Selection-Genetic Centre of Sheep Breeding, 1 Soborna str., Ascania-Nova, Chaplynskyy district, Kherson region, 75230, Ukraine, V. S. Yakovchuk, Institute of Animal Husbandry in Steppe Regions "Ascania-Nova" named after M. F. Ivanov's — National Scientific Selection-Genetic Centre of Sheep Breeding, 1 Soborna str., Ascania-Nova, Chaplynskyy district, Kherson region, 75230, Ukraine
2019 The Animal Biology  

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The role of progesterone in ovarian follicular growth and development was studied in female sheep. In Experiment 1, ovarian venous concentrations of oestradiol and ovarian follicular steroidogenesis were assessed during seasonal anoestrus and compared with those observed during the luteal phase of the breeding season. Ovarian venous blood was sampled for six hours, at the end of which time the ovaries were removed so the steroidogenic function of the follicles could be measured by the amount of
more » ... oestradiol and total androgen produced in vitro. Ovarian venous concentrations of oestradiol during anoestrus were about half those during the luteal phase. The ovaries of anoestrous ewes contained equal numbers of small follicles (<2 mm in diameter) and more medium-sized follicles (2 to 4 mm) than those of ewes in the luteal phase. Ovaries contained several large follicles (> 4 mm) during the uteal phase but none during anoestrus. Small follicles produced equal amounts of oestradiol in vitro in the two seasons, but medium follicles of anoestrous ewes produced more than medium follicles from luteal phase ewes. The same pattern applied to total androgen production and thus the oestradiol:androgen (E:A) ratio. The large follicles from the luteal phase produced the most oestradiol and the least total androgen. Experiment 2 tested whether these differences were due to seasonal differences in progesterone concentrations. Follicles were collected from two groups of anoestrous ewes, one of which was pretreated with a single injection of exogenous progesterone. The four largest ovarian follicles were dissected and cultured in vitro. In all cases, oestradiol production from follicles >3 mm was greater than that from follicles <3 mm, but was not significantly affected by progesterone priming. However, androgen production by the >3 mm follicles was reduced by progesterone priming, so the E:A ratio was greatly increased. These observations suggest that progesterone facilitates follicular function during the breeding season, possibly by stimulating the aromatization of androgens, and that absence of this effect may be one of the factors limiting follicle development past the 4 mm stage during seasonal anoestrus.
doi:10.15407/animbiol21.04.058 fatcat:lsazgo2ewrhwbhegnnbj6d3ska
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I. V. Lobachova, Institute of Animal Husbandry in Steppe Regions "Ascania-Nova" named after M. F. Ivanov's — National Scientific Selection-Genetic Centre of Sheep Breeding, 1 Soborna str., Ascania-Nova, Chaplynskyy district, Kherson region, 75230, Ukraine, V. S. Yakovchuk, Institute of Animal Husbandry in Steppe Regions "Ascania-Nova" named after M. F. Ivanov's — National Scientific Selection-Genetic Centre of Sheep Breeding, 1 Soborna str., Ascania-Nova, Chaplynskyy district, Kherson region, 75230, Ukraine. "The addition of stimulation scheme with anti-esterase substances improves the ewe lambing rate." The Animal Biology 21.4 (2019) 58-64