Determination of Physiological Particularities of the Sexual Cycle and Breeding Season of Pramenka Breed

Cilj našeg istraživanja bio je određivanje fizioloških posebnosti spolnog ciklusa i rasplodne sezone ovaca pasmine lička pramenka. U tu svrhu uzorkovana je krv ovcama i ovnu te rađena orhidometrija ovna u periodu od 10. 6. 2011. do 05. 09. 2012. godine radi utvrđivanja sezonosti. U periodu od 10.–31. listopada 2012. godine uzorkovana je krv ovaca s ciljem određivanja duljine trajanja spolnoga ciklusa s time da je estrus ovaca prethodno sinkroniziran dvokratnom i.m. aplikacijom (u razmaku od 12 dana) sintetičkog analoga prostaglandina F2α (Estrumate®, cloprostenol) u dozi od 75 μg. Koncentracija progesterona i testosterona u serumu je analizirana pomoću automatskog sistema Immulite® One. Analiza LH rađena je pomoću Imunoenzimnog testa (ELISA). Statistička analiza podataka načinjena je pomoću programskog paketa SAS (Statistical Analysis Software) 9.1.3. Na osnovu dobivenih podataka o koncentraciji progesterona zaključili smo da sezona spolne aktivnosti započinje krajem srpnja. Većina ovaca u pokusu ulazi u sezonu krajem kolovoza i tijekom rujna, a nastavlja sa spolnom aktivnošću sve do prosinca. Vrijednosti koncentracije testosterona i orhidometrije u ovna bilježe značajniji porast testosterona tijekom kolovoza i rujna te nagli pad u prosincu, dok opseg skrotuma raste već od lipnja, ali postepeno opada krajem zime i u proljeće. Kao posljedica pojačane hranidbe potpunom krmnom smjesom za ovce, tri mjeseca prije ulaska u sezonu 2012. godine, i poboljšanja kondicije, početak sezone nastupio u prosjeku 19 dana ranije u odnosu na 2011. godinu. Trajanje spolnog ciklusa u ovaca ličke pramenke je u prosjeku iznosilo 17,2 dana. Određeno je prosječno trajanje lutealne faze u ličke pramenke od 13,8 dana, a folikularne 3,4 dana. Prosječno trajanje LH vala iznosilo je 12,4 sati s rasponom od 8 do 16 sati te je za njegovu detekciju dostatno uzorkovanje krvi svakih osam sati.The objective of this study was to determine the physiological characteristics and particularities of the sexual cycle and breeding season of the Pramenka sheep breed - Lika strain. For this purpose, during the period from 10 June 2011 to 05 September 2012, blood was sampled from sheep and one ram and orchidometry performed on the ram to determine reproductive seasonality. In the period from 10-31 October 2012, sheep blood was sampled to determine the duration of sexual cycle, in which oestrus was previously synchronized with i.m. application (in a 12-day interval) of a synthetic analogue of prostaglandin F2α (Estrumate®, cloprostenol) in a dose of 75 mg. Concentrations of progesterone and testosterone were analyzed using the automatic system Immulite® One. Analysis of the LH was performed using ELISA (ELISA). Statistical analysis was conducting using the software package SAS (Statistical Analysis Software) 9.1.3. The results of progesterone concentrations indicated that the sexual activity season begins in late July. Most sheep in the study entered the season in late August and in September, and continued with sexual activity until December. Concentrations of testosterone and ram orchidometry recorded a significant increase during August and September and a sharp decline in December, while the girth of the scrotum increased beginning in June, and gradually declined in late winter and spring. As a consequence of increased feeding with complete feed three months before the start of the season in 2012, the physical condition of sheep was improved and the season started on average 19 days earlier than in 2011. The average duration of oestrus in sheep was 17.2 days. The average length of the luteal phase in the Pramenka breed - Lika strain was 13.8 days, and the follicular phase 3.4 days. The average duration of the LH wave was 12.4 hours, with a range of 8 to 16 hours, and therefore, adequate blood sampling every eight hours is sufficient for its detection