Utjecaj paragenetskih čimbenika na veličinu legla, dob pri prvom janjenju i međujanjidbeno razdoblje ovaca romanovske pasmine u Hrvatskoj

Reproductive traits are of paramountimportance in an efficient lamb production system. In Croatia, values of reproductive traits of Romanov sheep are below the average expected for this breed, indicating the need for improvement of these traits to exploit the breed’s full reproductive potential. This study was conducted on 260 Romanov ewes located at a commercial Romanov sheep farm in Croatia. All ewes were kept under similar conditions, and reproductive management was based on accelerated lambing with continuous mating. Linear models with fixed effects were used to estimate the influence of year of birth/lambing, season of birth/lambing, ram, parity and litter type on litter size (LS), age at first lambing (AFL) and lambing interval (LI). Average LS was 2.11 ± 0.71, while the year of lambing and parity were the most important factors affecting this trait. The smallest litters were recorded after 1st parity (1.77 ± 0.06), and the largest after 5th parity (2.21 ± 0.08). AFL averaged 388.5 ± 72.4 days. All investigated non-genetic factors had a significant (P<0.05) influence on AFL, with year of birth as most important. The average LI was 241.2 ± 70.8 days. A significant (P<0.05) influence of all factors on LI was observed. Ewes lambing in spring (200.2 ± 7.9 days) or summer (190.5 ±6.6 days) had a significantly (P<0.05) shorter LI than ewes lambing in autumn (227.7 ± 8.3 days) or winter (237.2 ± 6.7 days). The longest LI was observed after the first parity (284.0 ±5.5 days). Average values for reproductive traits in the examined population of Romanov sheep were higher than those reported in the official Croatian database for breeding sheep. Non-genetic factors have a significant influence on the variation of reproductive traits of Romanov sheep, and therefore should be considered when assessing ewes’ reproductive performance.U mesnom ovčarstvu reprodukcijska svojstva su izrazito važna. U Hrvatskoj su vrijednosti reproduktivnih svojstava romanovske ovce u odnosu na očekivane vrijednosti za tu pasminu ispodprosječne, što ukazuje da je poboljšanje ovih svojstava neophodno kako bi se iskoristio puni reprodukcijski potencijal pasmine. Ovo istraživanje provedeno je na 260 ovaca romanovske pasmine smještenih na jednoj komercijalnoj farmi ovaca u Hrvatskoj. Sve ovce držane su u sličnim uvjetima, a reprodukcijski menadžment temeljio se na učestalim janjenjima s kontinuiranim razmnožavanjem. Linearni modeli s fiksnim učincima korišteni su za procjenu utjecaja godine rođenja/janjenja, sezone rođenja/janjenja, ovna, redoslijeda janjenja i tipa legla na veličinu legla (VL), dob pri prvom janjenju (DPJ) i međujanjidbeno razdoblje (MR). Prosječna VL iznosila je 2,11±0,71, dok su godina janjenja i redoslijed janjenja bili najvažniji čimbenici koji su utjecali na ovo svojstvo. Najmanja legla zabilježena su nakon 1. janjenja (1,77±0,06), a najveća nakon 5. janjenja (2,21±0,08). DPJ je u prosjeku iznosila 388,5±72,4 dana. Svi istraživani negenetski čimbenici imali su značajan (P<0,05) utjecaj na DPJ, pri čemu je najvažnija bila godina rođenja. Prosječno MR je bilo 241,2±70,8 dana. Uočen je značajan (P<0,05) utjecaj svih čimbenika na MR. Ovce koje su se janjile u proljeće (200,2±7,9 dana) i ljeto (190,5±6,6 dana) imale su značajno (P