Risk Factors Associated with Passive Immunity, Health, Birth Weight and Growth Performance in Lambs: III-The Relationship among Passive Immunity, Birth Weight, Gender, Birth Type, Parity, Dam's Health, and Lambing Season

This study was designed to investigate the effect of risk factors such as gender, birth type, parity, dam's health and lambing season associated with passive immunity and birth weight and to also determine interrelationship between passive immunity and birth weight. This study included 301 ewes and 347 lambs born to them on two local Akkaraman crossbred flocks in Kars. Lambs were blood sampled for serum IgG concentration at 24 hours after birth (SIgGC-24) and epidemiological parameters were recorded at birth. Parity, type of birth and gender were significantly associated with birth weight (R-2=0.339, P<0.001) on multivariable stepwise regression analysis as single born lambs (P<0.001), male (P<0.001) and lambs born to dams previously lambed (P<0.001) were significantly heavier. There was a significant (P<0.001) and positive (R-2=0.136) linear relationship between birth weight and passive immunity, but only in ill lambs during the neonatal period. In General Linear Model (GLM), lambs born with low birth weight (<= 3 kg) had significantly lower SIgGC-24 than those born with medium (>3 to <= 4) (P<0.01) or high (>4 kg) (P<0.001) birth weight. Similarly lambs born as a twin and born to unhealthy dams had significantly lower SIgGC-24 (P<0.05). In conclusion, some farm management practices and animal characteristics were associated with birth weight and passive immunity and also birth weight had affect on passive immunity. For a productive and profitable farming, producers should take these variables into account and develop appropriate management strategies.