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Determination of physiological characteristics and specificities of estrous and breeding season in Pramenka breed Lika strain sheep

The aim of this research was to determine the physiological characteristics and specificities of oestrus cycle and breeding season of Pramenka breed Lika strain sheep measuring hormone levels (progesterone, testosterone and LH). For this purpose, blood samples were taken from eight sheep and one ram of Pramenka breed lika strain in two year period (2011 and 2012) and orchidometry was performed in ram for determination of breeding season. In order to determine the characteristics and duration of oestrus cycle, blood was sampled in sheep during 21 days (in full breeding season), after oestrus synchronisation with two prostaglandin F2α applications (with an interval of 12 days). Concentrations of progesterone and testosterone were analyzed using an automatic system Immulite ® One. Analysis of the LH hormone was done by ELISA. On the basis of the obtained data we have concluded that the season of breeding activity begins in late July. Most of the sheep enter the season in late August and September, and continue with breeding activity through December. Concentrations of testosterone and results of orchidometry in ram are corresponding with breeding season of sheep. The oestrous cycle in sheep lasts 17.2 days on average, with luteal phase of 13.8 days and follicular of 3.4 days. The average duration of LH surge was 12.4 hours with a range of 8 to 16 hours.

Pramenka breed - Lika strain; seasonality; sexual cycle; LH hormone; progesterone

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