DIETARY-EFFECTS ON IMMUNE-RESPONSE OF FAST-GROWING CHICKS TO INOCULATION OF SHEEP ERYTHROCYTES AND ESCHERICHIA-COLI

Responses to SRBC and Escherichia coli inoculations were measured duri ng the early posthatch period in broiler cockerels fed diets differing in nutrient density. Diet A consisted of 20% protein and 2,685 kcal M E/kg and Diet B consisted of 24% protein and 3,146 kcal ME/kg. There w as no effect of diet on antibody response of chicks inoculated at 10 d of age with 0.25, 2.50, 5.00, or 25.00% suspensions of SRBC. A signif icantly larger proportion of chicks, however, produced antibody at the 25.00% than at the 0.25% dosage of SRBC. When inoculated at 15 d of a ge with 10(-6), 10(-4), or 10(-2) dosage of E. coli, there were no sig nificant diet by (Key words: nutrient density, early growth, feed dosa ge interactions for lesion scores, or relative change in BW 24, 48, an d 120 h after inoculation. There were differences among E. coli dosage s for severity of lesions and mortality, with rankings being 10(-2) > 10(-4) > 10(-6). Lesion scores and mortality were higher for the chick s fed Diet B than those fed Diet A. Also, deleterious effects of E. co li on BW 24, 48, and 120 h after inoculation were greater for chicks f ed Diet B than for chicks fed Diet A. Responses to inoculations of SRB C and E. coli of broilers fed a diet with a lower nutrient density wer e equal or superior to those of broilers fed a diet with a higher nutr ient density.