Tryptophan methylester modulation of poult responses to Bordetella avium

North Carolina State University, Department of Poultry Science, Raleigh 27695-7635, USA. fwedens@mindspring.com

On the day of hatching, four groups of poults [Control, L-tryptophan methylester (LTME), Bordetella avium-infected, and B. avium-infected plus LTME] were established and placed into heated metal brooding batteries. Bordetella avium infection caused a significant depression in body temperature within 24 h after intranasal challenge with the W strain, and the hypothermia persisted through 21 d of age. L-Tryptophan methylester, a water-soluble form of tryptophan, was given by oral gavage daily in saline at a concentration of 50 mg per poult beginning 4 d after hatch. Within 2 d after initiation of LTME treatments, colonic temperature of B. avium-infected poults was elevated to the level of Controls and remained at that level throughout the experimental period. The BW of B. avium-infected poults were reduced significantly. The LTME treatment caused a significant BW increase in the B. avium-infected poults, but the increase was not to the level of Controls. The anti-sheep red blood cell antibody titers in B. avium-infected poults were not affected significantly. However, LTME treatment induced a significant increase in anti-sheep red blood cell antibody titers in both the infected and Control poults. Based upon data reported herein, it was concluded that feed intake depression associated with development of bordetellosis caused the poults to react more specifically to a mild tryptophan deficiency than to other nutrient deficiencies. The tryptophan deficiency caused a growth depression that was only partially alleviated by daily supplementation of LTME. The physiological responses to daily supplementation of LTME to B. avium-infected poults suggested that growth depression and poor performance was not limited to dietary deficiency of tryptophan.