Immunocompetence traits and their association with layer economic traits in Rhode Island Red chicken

Rhode Island Red (RIR), a brown-egger dual-purpose chicken breed, preferred by small poultry farmers for rearing in backyard and rural systems. Present investigation was carried out on single-hatched RIR chicks to assess important immunocompetence (IC) and layer traits and also their inter-relationship. Data (n=100) on IC and layer economic traits were analyzed by least square ANOVA taking sire as random effect in the model. Least-squares means of HA titre, serum lysozyme and serum IgG were 9.33±0.34, 4.42±0.18 μl/ml and 8.72±0.41 mg/ml, resp. Least square means of age at first egg (AFE), body weight at 16 weeks (BW16), egg weight at 28 (EW28), 40 (EW40) and 64 (EW64) weeks of age, egg production up to 40 (EN40) and 64 (EN64) weeks of age were 133.68±0.90days, 1220.60±21.57 g, 44.73±0.34 g, 47.62±0.41 g, 51.89±0.81 g, 118.11±1.21 eggs and 219.39±4.09 eggs, respectively. Sire effect was significant on BW16 (P≤0.05), EW64 (P≤0.02) and EP40 (P≤0.01). Heritability estimates were low to medium for IC traits, high for growth traits and low to medium for layer economic traits. HA titre showed very low phenotypic correlations with all traits except EW64 where it was low and positive. Serum lysozyme level had high negative correlation with serum IgG level, EP40 and EP64; low to moderate with EW28 and EW64, positive and high correlation with BW16 and EW28 and negative with AFE. Serum IgG concentration had high and positive correlation with body and egg weights at different ages but negative correlation with EP40 and EP64. Phenotypic correlation between IC traits and egg production traits were mostly positive and moderate to low. The results of present investigations indicated that the various immunocompetence traits are controlled by additive and non-additive genetic effects and hence indirect selection based on these traits might lead to enhancement of overall improvement of production as well as immunocompetence status in RIR chicken.