Lambing Interval in Jezersko-Solčava and Improved Jezersko-Solčava Breed

The effects on lambing interval (LI) in Improved Jezersko-Solčava (IJS) breed were studied. Due to the reason that IJS breed originates from Jezersko-Solčava (JS) breed, both breeds were included into the analysis. The data were obtained from the Republic Data Base for Selection of Small Ruminants, between 1993 and 2008. The analysis included 66,755 lambings from 280 breeders. The statistical model included breed, parity, litter size at previous lambing, month of the previous lambing, year of the previous lambing, breed of the ram, geographical location of the flock, interaction between month of the previous lambing and breed of the ram, interaction between parity and month of the previous lambing, interaction between breed of the ewe and month of the previous lambing, and interaction between breed of the ewe and litter size at previous lambing as fixed effects. Flock and interaction between year of the previous lambing and flock were treated randomly. Month of the previous lambing affects LI, which is gradually shortening from February to August, and prolonging from August to February. The number of live born lambs significantly affected LI. LI between the first and the second parity and between the second and the third parity was longer than between higher parities. From 1993 to 1999, the LI was decreasing, and increasing thereafter. Ewes mated with JS ram had longer lambing interval than ewes mated with IJS ram. Among all observed effects, flock affected LI the most