The effects of genetic and non genetic factors on survival and longevity of Kourdi lambs from birth to yearling

The effect of genetic and non genetic factors on length of life and survival records of Kourdi lambs, 7469 records collected from 1988 to 2011 in Hossin Abad Sheep Breeding Station in Shirvan were used in this study that which belonging to 187 sire and 2258 dam. Data were analysed using linear models with included fixed effects of year and month and type of birth, sex of lamb, age of dam and lamb's birth weight as linear and quadratic covariate, and direct additive genetic, maternal additive genetic, maternal common environmental and residual random effects. Overall mean of length of life and cumulative survival rate up to yearling were 274.3 ± 165.3 days and 0.62 ± 0.26 percent. The effect of year, month, type of birth, birth weight and sex of lamb were significant on length of life and survival from birth to yearling. Male lambs had lower life length and survival rate than females in all ages. With increasing birth weight survival rate decreased. The direct heritabilities of length of life and survival rate estimated from different linear models were low (0.01 to 0.006). The maternal heritability ranged from zero to 0.02. The estimates of heritability in logarithmic, original and effective scale obtained from sire model with weibull function were higher than values estimated by different linear models. Estimated heritability for length of productive life was 0.013 and genetic correlation between satiability traits were high and positive.