RESPONSES OF DWARF AND NORMAL CHICKENS TO FEED RESTRICTION, EIMERIA-TENELLA INFECTION, AND SHEEP RED-BLOOD-CELL ANTIGEN

Relationships among stress responses, habituation to feed restriction, resistance to Eimeria tenella, and antibody response to SRBC were stu died in dwarf and normal White Plymouth Rocks. Transfer of chicks at 2 2 days of age from starter to developer batteries resulted in an incre ase within 24 h of heterophil:lymphocyte (H:L) ratios of chicks of bot h genotypes. Restriction of feed intake from ad libitum (AL) to 60% of ad libitum reduced body weight and increased size of the crop-esophag us. As measured by H:L ratios, the effect of adapting to the 60% feed restriction dissipated between 12 and 16 days after initiation. Releas e of 60% restricted chicks to 80% of ad libitum also elicited a stress response as measured by H:L. These effects were noted in both dwarf a nd normal chicks. Time required for chicks on restriction to consume t heir daily allotment was curvilinear with a plateau occurring at a sma ller value for dwarf than for normal chicks. Neither feeding regimen n or genotype had an effect on antibody response to SRBC. Resistance to E. tenella was greater in normal than dwarf chicks and greater for res tricted than ad libitum chicks.