Inbreeding depression in Leccese sheep

Three closed flocks of Leccese sheep reared in southern Italy were used to study the effects of inbreeding on productive and reproductive performances. All the animals were grouped into three classes according to the inbreeding coefficients obtained by their pedigree: the first class included non-inbred animals (F = 0%); and the second and third classes included inbred animals (0 < F < 10% and F≥10%, respectively). Birth and weaning (40±3 days) live weights of 531 ewe lambs born throughout 2003–2005 were recorded and were investigated throughout 2004–2006 for their fertility, prolificacy and fecundity amounting 1282 observations. Live weights at birth (BW) of lambs in first class (F = 0) and in second class were statistically not different from each other but these were heavier (P < 0.01) than those included in third class (F≥10). The same pattern was observed in live weights at weaning (WW) but the relative values were statistically different only for P < 0.05. Likewise all reproductive traits investigated showed strong decreases related to the increasing inbreeding rate.