Excess dietary L-cysteine causes lethal metabolic acidosis in chicks.
A 72-h time-course study was conducted to elucidate the physiological mechanism underlying cysteine (Cys) toxicity in chicks beginning at 8-d posthatch. Biochemical markers quantified in plasma and liver samples collected from chicks receiving 30 g/kg excess dietary Cys were compared with baseline measurements from chicks receiving an unsupplemented corn-soybean meal diet over a 72-h feeding period. Concomitant with chick mortality were indices of acute metabolic acidosis, including a rapid increase (P < 0.001) in anion gap that resulted from a reduction (P < 0.001) in plasma HCO(3)(-) of approximately 40% and a 2.8-fold increase (P < 0.001) in plasma sulfate in chicks receiving excess Cys. Additionally, provision of 30 g/kg excess Cys resulted in a 1.5-fold increase (P < 0.05) in hepatic oxidized glutathione compared with the 0-h control time-point. Excess dietary Cys did not affect plasma free Met, but plasma free Cys increased (P < 0.05) from 89 to 107 mumol/L at 12 h and remained elevated through 36 h. Strikingly, ingestion of 30 g/kg excess Cys caused more than a doubling (P < 0.001) of plasma free cystine, the oxidized form of Cys, beginning 12 h after initiating the study, and it remained elevated throughout the 72-h feeding period. Taken together, these data suggest that ingestion of 30 g/kg excess l-Cys causes both acute metabolic acidosis and oxidative stress in young chicks when fed a nutritionally adequate, corn-soybean meal diet.
Dilger
Ryan N
RN
Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. rdilger2@illinois.edu
Baker
David H
DH
D000137:Acid-Base Imbalance; D000138:Acidosis / Q000139:chemically induced / Q000662:veterinary*; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001639:Bicarbonates / Q000097:blood; D015415:Biomarkers; D002645:Chickens; D003545:Cysteine / Q000008:administration & dosage* / Q000009:adverse effects* / Q000097:blood; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D019803:Glutathione Disulfide / Q000032:analysis; D008099:Liver / Q000378:metabolism; D008297:Male; D008715:Methionine / Q000097:blood; D018384:Oxidative Stress; D011201:Poultry Diseases / Q000139:chemically induced*; D011897:Random Allocation; D013997:Time Factors
D001639:Bicarbonates; D015415:Biomarkers; D008715:Methionine; D003545:Cysteine; D019803:Glutathione Disulfide