DIET AND HUMORAL RESPONSIVENESS OF LINES OF CHICKENS DIVERGENTLY SELECTED FOR ANTIBODY-RESPONSE TO SHEEP RED-BLOOD-CELLS

Growth and humoral immune response were studied in lines of white legh orn chickens selected for high (HA) or low (LA) 5-day antibody titers to an i.v. inoculation with 0.1 ml of a 0.25% suspension of sheep red blood cells (SRBC) antigen(s). Chicks were fed either a high (E) or lo w (A) nutrient density diet from hatch onward. Chicks from each line-d iet subclass were inoculated i.v. with 0.1 mi of either 0.25% or 2.50% suspension of SRBC at either 7, 14, 21, or 28 days of age. Antibody t iters were measured 5, 10, and 20 days after inoculation. LA chicks we re heavier than HA chicks at 7 days of age and thereafter. Chicks fed diet E were heavier than those fed diet A. Feed efficiency was influen ced by diet (E > A) at 21 and 28 days of age and line (LA > HA) at 28 days of age. In all but one case, antibody titers to SRBC were higher in HA than LA chicks. Also, the frequency of nonresponders of chicks i noculated with SRBC at 7 days of age was higher for LA than HA chicks. The higher dosage elicited greater 5-day antibody responses in LA but not in HA chicks inoculated at 28 days of age. Dietary effects on SRB C antibody were generally unimportant except for occasional interactio ns of dosage and line.