Correlation of innate immunocompetence traits with economic traits in various indigenous and exotic breeds of chicken

Abstract

Birds (433) were utilized for investigation at 7 weeks of age and at 45 weeks of age (119). The immunological traits measured included humoral response like HA, MER and MES; non-specific immune responses like CPW and APW complement and PI and CMI response. In two broiler lines, body weight at 6, 7, 8, 9 and 10 weeks of age were measured in addition to body weight at hatch and feed efficiency to 10 weeks of age. In rest of the genetic groups, the economic traits measured included day old body weight, body weight, shank length and keel length at 5, 10, 15 and 20 weeks of age, age at sexual maturity, egg production as number of eggs to 40 weeks of age, egg weight at 40 weeks of age, per cent mortality during different periods up to 20 weeks of age, feed consumption per day, and feed conversion ratio to produce a dozen of eggs or a kg of egg mass. All the traits were measured on individual birds except for per cent mortality and feed efficiency in broilers. For evaluation of humoral and nonspecific responses except PI, the birds were immunized with sheep red blood cells (SRBCS) by injecting 1 ml of 25% (v/v) SRBCs suspension in PBS intramuscularly in thigh muscle. The various components of immunocompetence parameters like humoral and nonspecific responses were measured on day 5, 12 and 19-post immunization. Natural antibodies for various immunocompetence traits were also measured on the day of SRBC injection. For evaluation of effect of age, birds of the Aseel, Kadakanath, Naked Neck and Frizzle were immunized against SRBCs at 45 weeks of age and immunocompetence traits were measured on day 0 and 7 p.i. CMI response was estimated by injecting 0.1 ml of PHA-P interdigitally (100 μg PHA-P/0.1 ml of PBS) between the 3rd and 4th toe of the right foot of each chicken as Foot index (FI) and was estimated by measuring the skin swelling. Data so collected were analyzed statistically utilizing appropriate statistical procedures to evaluate correlation coefficients among immunological and economic traits calculated as simple product moment correlation. HA was positively correlated with MER, CPW and APW and negatively correlated with FI and PI. The trend remained the same on all the days of study. The correlation of MER with CPW and APW were mostly positive and did not present any definite trend in both magnitude and direction with FI and PI. The correlations between CPW and APW were positive and highly significant. No definite trend was observed for the correlation between CPW with FI and PI. The trend remained the same for APW also. FI and PI were negatively correlated in indigenous breeds and broilers but positively correlated in Dahlem Red and White Leghorns. Irrespective of direction, all the estimates were small. HA was seen to be positively correlated with body weight, shank length, keel length, ASM and negatively correlated with egg production and mortality. MER was positively correlated with body weight, shank length, keel length and ASM and negatively correlated with egg production and mortality. The relationship of FI and PI with body weight, shank length, and keel length was negative. Relation between FI and egg production was negative. The relationship of immunocompetence traits with economic traits presented in the literature as well as realized in this study did not lead to any definite conclusion suggesting more study to quantify the magnitude and direction of relationship for their use in practical breeding programmes.