Abstract
Two-way selection for antibody titers to Leucocytozoon caulleryi was carried out using White Leghorn (WL) and Rhode Island Red (RIR) strains. The selection was conducted for five generations in WL and four generations in RIR. The antibody titer was measured under the condition of natural infection, in which the proportion of infected chickens usually being more than 90%.
The selection was effective and, with the exception of 2nd and 3rd generations in RIR, the difference between the high (H) and low (L) lines increased with each successive generation of selection. Realized heritability was as much as 0.17 in WL and 0.15 in RIR. Egg production in the summer, epidemic season of leucocytozoonosis, was better in the L line than in the H line. The proportion of chickens negative to the antibody to L. caulleryi was also higher in the L line. These results suggest that the H line is more susceptible to leucocytozoonosis and the L line more resistant.
Changes in gene frequencies at five polymorphic loci concerning blood group A, B, D. and E, and plasma alkaline phosphatase Akp were examined. The frequency of alleles only at the B locus showed consistent changes throughout the period of selection.
