Influence of Age on the Temperature Response of Chickens to Escherichia coli and Salmonella typhimurium Endotoxins

Abstract

An experiment was conducted to investigate the influence of age on the temperature responses of chickens given bacterial endotoxins. Broiler cockerels 1 to 8 weeks of age received a single intravenous injection of either distilled water (controls), Escherichia coli 0127:B8, or Salmonella typhimurium endotoxins. Rectal temperatures were recorded before and after injection, the birds were placed in an environmental chamber preheated to 33 C, and thereafter rectal temperatures were taken every 30 min for 180 min. In one-week-old chicks, a significant temperature loss was found 30 min after E. coli treatment, and this was followed 60 min later by a significant increase in rectal temperature. The E. coli and S. typhimurium treatments caused a .4 and .5 C increase, respectively, in 2-week-old chicks. Birds aged 3 to 8 weeks developed fevers with maximum changes in rectal temperatures ranging from .3 to 1.6 C. Seven- and eight-week-old chicks developed the highest and most persistent fevers. The febrile response of 5 to 8 week-old chicks was of longer duration than that of younger chicks. It was concluded that the febrile response following endotoxin administration is affected by age.