Diet and Humoral Responsiveness of Lines of Chickens Divergently Selected for Antibody Response to Sheep Red Blood Cells

Abstract

Growth and humoral immune response were studied in lines of white leghorn 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 low (A) nutrient density diet from hatch onward. Chicks from each line-diet subclass were inoculated i.v. with 0.1 ml of either 0.25% or 2.50% suspension of SRBC at either 7, 14, 21, or 28 days of age. Antibody titers were measured 5, 10, and 20 days after inoculation. LA chicks were 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 influenced 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 inoculated 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 SRBC antibody were generally unimportant except for occasional interactions of dosage and line.