Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2007
Publication Date: 6/25/2007
Citation: Olanrewaju, H.A., Thaxton, J.P., Dozier III, W.A., Branton, S.L. 2007. Electrolyte Diets, Stress, and Acid-Base Balance in Broiler Chickens. Poultry Science. 86:1363-1371. Interpretive Summary: Poultry welfare concerns include understanding the full scope of physiological stress, especially the relationship of physiological stress, acid-base balance and deficiency of dietary electrolyte balance (DEB) during the hot summer temperatures when their feed intake decreased and consequently their nutrient intake. Several management procedures are being implemented in an attempt to minimize the deleterious effects of stress and the concept of high DEB has also been applied for different species. The results of this study not only indicate that chickens experiencing physiological stress show no change in their acid-base balance but also high DEB increased blood oxygen content to enable bird to fulfill the required oxygen demand, resulting from hypoxemia. These results are important to the poultry industry in understanding the physiological importance of DEB under stressful condition when chickens must not only maintain their acid-base balance but must also compensate for lost electrolytes under stressful condition to enable them to meet nutrient requirement for their metabolic needs.
Technical Abstract: The aim of this study was to compare acid-base balance in broiler chickens provided diets’ containing two different dietary electrolyte balances (DEB) and administered either adrenocorticotropic hormone (ACTH) or saline. Diets were moderate (M; 174 mEq/kg) or high (H; 241 mEq/kg) DEB by altering Na-K-Cl based upon actual analysis. These diets were fed ad libitum from d 0 to 49 d of age. Osmotic pumps delivered 8 IU ACTH in saline/kg BW/d for 7 d or the same saline volume as used in ACTH at 1'L/h for 7 d. Pumps were implanted on d 35 following sample collection. Post-implantation blood samples were taken on d 42 and 49. The experiment was designed as a split plot with main unit consisting of 4 treatments with factorial treatments structure (2 ACTH treatments × 2 diets) arranged in a completely randomized design. Significant DEB × ACTH interactions (P' 0.04) were determined for pCO2 and pO2 at 49 d. These differences infer when the H DEB diet was fed to the control and ACTH groups that pCO2 and pO2 were altered, whereas when the M DEB diet was fed to the control and ACTH groups, pCO2 and pO2 were without change. Infusion of ACTH increased (P' 0.05) hematocrit, hemoglobin, pCO2, corticosterone, osmolality, mean corpuscular hemoglobin concentration (McHc), and HCO3- and reduced (P' 0.05) pO2, Na+, K+, anion gap, pH, Ca2+, BW, and Cl- compared to the control group on d 42 and 49. Birds fed the H DEB diet exhibited higher (P' 0.05) pO2 than birds provided the M DEB diet. The diet formulated to H DEB partially blocked the effect of ACTH on pO2 and pCO2. However, there was reduction of pO2 under ACTH treatment in both diets compared to saline group due to the increased need for O2 to support gluconeogenic energy production, the bird responded by increased erythropoiesis. This adaptive response provided greater numbers of erythrocytes and thus a higher amount of circulating hemoglobin to deliver O2 for metabolism. Diet formulated to the H DEB partially attenuated adaptive stress condition.