Antibody responses and body weights of chicken lines selected for high and low humoral responsiveness to sheep red blood cells. 2. Effects of separate application of Freund's Complete and Incomplete Adjuvant and antigen.

Antibody (Ab) responses to SRBC, BSA, Mycobacterium butyricum, and Escherichia coli lipopolysaccharide (LPS) were measured in two chicken lines divergently selected for high and low Ab responses to SRBC, and in a randombred control line. Levels of Ab binding SRBC, BSA, and Mycobacterium protein, but not LPS were higher in the high Ab producing (H) line than in the control (C) and low Ab producing (L) lines (P < 0.05), and at almost every time, the L line showed significantly lower titers than the H and C lines. In the H and C lines, Ab responses to SRBC were enhanced when Complete Freund's Adjuvant (CFA) or Incomplete Freund's Adjuvant (IFA) were simultaneously administered on a separate location than SRBC. In the L line, Ab titers to SRBC and BSA were enhanced when antigen was administered emulsified in CFA. At all times until 28 d after sensitization the C and L line birds were significantly heavier than birds of the H line. Body weight, body growth, and percentage body growth were impaired in birds that received antigen emulsified in CFA, which suggested a negative relationship between BW gain and immune responses to Mycobacteria protein. Prolonged divergent selection for Ab responses to SRBC resulted into two lines that not only differ in Ab responses to T cell-dependent antigens but also in BW. In contrast to previous findings with the current lines, line differences with respect to Ab responses were not abolished by CFA treatment.