Effect of non-genetic factors on survivability and cumulative mortality of Kashmir merino lambs

A study was designed to evaluate the effect of different factors affecting survivability and cumulative mortality up to yearling age in lambs maintained at Government Sheep Breeding Farm, Kralapathri (Jammu and Kashmir). Data of 4085 birth records spread over 11 years (2006 to 2017) pertaining to Kashmir Merino sheep were used. The overall least squares means of pre-weaning (0–3 month) and post-weaning (3–6, 6–9 and 9–12 months) survivability in Kashmir Merino lambs were 88.33±1.38, 95.69±11.03, 97.96±0.56 and 98.28±0.00% respectively. The effect of year was significant (P<0.01) on all the traits. The effect of sex was significant (P<0.01) on survivability from 0–3, 3–6 months and 6–9 months with higher survivability in female lambs. The effect of parity was significant (P<0.05) only on survivability from 0–3 months and lambs born to primiparous ewes had lower survivability. The overall mean lamb mortality rate was 18.43±2.17% from birth to 12 months age. The effects of year and sex were significant (P<0.01/0.05) on all the traits under study. The effect of parity was significant (P<0.05) on mortality up to 1 and 3 months only while effects of birth type and birth weight remained non-significant for all the traits under study. The heritability estimates for cumulative mortalities from birth to 12 months were low and ranging from 0.04±0.27 to 0.25±0.22. Improvement in management of pregnant and lactating ewes will effectively decrease mortality rate in this flock and improve production of breeding rams and ewes.