EFFECT OF COLD-ACCLIMATION ON THE BROILER CHICKS RESISTANCE TO ACUTE AFLATOXICOSIS

The effect of acclimation to environmental temperatures of 10 to 12, 14 to 16, or 28 to 30 C on the resistance of broiler chicks to acute aflatoxicosis was studied in a series of four experiments. Chicks acclimated to 10 to 12 C were more resistant to a single oral dose of aflatoxin (8 mg per kg of BW) after 10 and 20 days than chicks acclimated to 28 to 30 C. However, chicks acclimated to 14 to 16 C required 20 days of acclimation before an increase in resistance was observed. Acclimation to 10 to 12 C for 14 days followed by acclimation to 28 to 30 C for 7 days resulted in no increase in the resistance of the chicks to an aflatoxin dose (8 mg per kg of BW) at 21 days, indicating that the resistance conveyed by cold acclimation was temporary. Sodium-pentobarbital sleeping time was significantly decreased and the cytochrome P-450 content was significantly increased after acclimating broiler chicks to 10 to 12 C. These observations suggest that stimulation of the microsomal mono-oxygenase system after cold acclimation may be responsible for the increased resistance of the broiler chick to acute aflatoxicosis.