Abstract
A divergent selection experiment for residual variance of litter size (Ve) has been carried out in rabbit. Increasing uniformity in litter size along all the reproductive life of females may be partially due to an improvement in immunological response to infectious diseases. After eight generations of selection, the H line exhibited higher percentage of lymphocytes, being the difference between lines D=4.11, with a probability P(D>0)=96%, and lower percentage of neutrophils (D=−4.19, (D<0)=97%). The L line presented similar percentage of lymphocytes than the H line after being
exposed to inactive RHD virus, and higher percentage of lymphocytes (D=9.22, P(D>0)= 98%) after being exposed to live attenuated myxoma virus. In conclusion,
selection for reduced Ve seems to improve immune response to pathogens; i.e., the L line appears to be more robust to diseases and more able to withstand adverse environmental conditions.
