DIETARY METHIONINE AND ANTIBODY-RESPONSE IN BROILER COCKERELS

Three experiments were conducted in which commercial broiler cockerels were fed ad libitum one of three diets (A, B and C) differing in meth ionine content (4.4, 5.8 or 8.5 g methionine/kg diet, respectively). S heep erythrocytes (SRBC) were injected iv (0.1 ml doses of 0.25%, 2.5% or 25% suspensions) at 14 days of age (doa) - (Experiment One); at 14 and 21 doa (Experiment Two); and at 14, 21 and 28 doa (Experiment Thr ee). Antibody titers in response to SRBC were measured at 5 and 12 day s after injection. At the time chicks were injected with SRBC, blood s amples were obtained from 10 individuals selected at random and the ra tio of heterophils to lymphocytes were determined. The ratio increased between 14 and 21 doa for all diets. Where differences in body weight s occurred due to diet, chicks fed Diet B were generally heavier than those fed Diet A. Antibody response to SRBC increased with age from 14 to 28 doa and with increasing dose of SRBC. Throughout the three expe riments there was only one instance (at 21 doa in Experiment Two) wher e there were differences in antibody titers due to variable levels of dietary methionine.