Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/9/2006
Publication Date: 7/1/2006
Citation: Olanrewaju, H.A., Wongpichet, S., Thaxton, J.P., Dozier III, W.A., and Branton, S.L. 2006 Stress and Acid-Base Balance in Chickens. Poultry Science 85:1266-1274. Interpretive Summary: Poultry welfare concerns include understanding the full scope of physiological stress: in particular, this includes the relationship of physiological stress, acid-base balance and gluconeogenesis associated with hot summer temperatures. The results of this study indicate that chickens experiencing physiological stress show no change in their-base balance but changes in acid-balance influence gluconeogenesis. These results are important to the poultry industry in understanding the physiological importance of ventilation coupled with evaporative cooling during the hot summer months when chickens must not only maintain their acid-base balance but must also increase their red blood cell production to insure adequate oxygen to meet their metabolic needs.
Technical Abstract: Two trials were conducted to study effects of stress caused by continuous infusion of ACTH on acid-base balance in broiler chickens. Osmotic pumps delivered 8 IU ACTH/kg BW/d for 7 d or saline at 1'L/h for 7 d. Blood samples were taken on d 0 (baseline values) and on d 4, 7, and 14 after onset of infusions. The ACTH treatment caused increased blood concentrations of hematocrit (cHct), hemoglobin (ctHb); mean corpuscular hemoglobin concentration (McHc), bicarbonate ion (HCO3-) partial pressure of carbon dioxide (ptCO2), anion gap, and corticosterone (CS), along with decreased blood concentrations of partial pressure of oxygen (ptO2), sodium ion (cNa+), potassium ion (cK+), and chloride ion (cCl-). Blood pH concentrations were not changed by ACTH treatment. Results indicate that stress induced by infusion of ACTH does not prevent homeostatic regulation of acid-base balance, as indicated by constant blood pH. However, due to the increased need for O2 to support gluconeogenic energy production, the bird responded by increased erythropoiesis. This adaptive response provided both greater numbers of erythrocytes and the total amount of circulating hemoglobin to deliver O2 for metabolism.