Calcium deficiency and food deprivation improve the response of chickens to acute heat stress

• Published in: The Journal of nutrition Vol. 123; no. 1; pp. 98 - 105
• Main Authors: Ait-Boulahsen, A. (North Carolina State University, Raleigh, NC), Garlich, J.D, Edens, F.W
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Nutritional Sciences 01.01.1993; American Institute of Nutrition
• Subjects: Acid-Base Equilibrium; AGOTAMIENTO POR EL CALOR; Animals; AVES DE CORRAL; Biological and medical sciences; Body Temperature; CALCIO; CALCIUM; Calcium - blood; Calcium - deficiency; CARENCE MINERALE; Chickens; COUP DE CHALEUR; DEFICIENCIA DE MINERALES; Diet; DIETA; EQUILIBRE ACIDOBASIQUE; EQUILIBRIO ACIDO-BASE; Food Deprivation - physiology; Fundamental and applied biological sciences. Psychology; Heat; Hot Temperature - adverse effects; INANICION; INANITION; Male; Phosphates - blood; Poultry; REGIME ALIMENTAIRE; Stress, Physiological - physiopathology; Thermoregulation. Hibernation. Estivation. Ecophysiology and environmental effects; Vertebrates: anatomy and physiology, studies on body, several organs or systems; VOLAILLE; Phosphatemia; Deficient diet; Nutrition; Calcium; Free ion; Body temperature; Thermoregulation; Tolerance; Environmental factor; Inorganic element; Feeding; Acid base balance; Vertebrata; Heat; Chicken; Aves; Hyperthermia; Nutritional status; Room temperature; Low calorie diet
• ISSN: 0022-3166; 1541-6100
• DOI: 10.1093/jn/123.1.98

The tolerance of chickens to acute heat stress may be modified by diet. Broiler chickens fed calcium-adequate (0.90% Ca) or -deficient (0.45% or 0.15% Ca) diets were either fed or not fed for 24 h and exposed to increasing temperatures (from 24 to 41 degrees C). Diets were fed for 7 d before heat stress in Experiment 1 and for 14 d before heat stress in Experiment 2. Body temperature, blood ionized Ca, pH, pCO2, plasma inorganic phosphate and total Ca were determined. During heat stress, Ca+2 and inorganic phosphate were depressed in all treatments. Feeding the 0.45% Ca diet for 7 d reduced hyperthermic body temperature of fed chickens but had no effect on body temperature of unfed chickens relative to the groups fed 0.90% Ca. No further improvement in body temperature response to heat stress was obtained by lowering the dietary Ca level to 0.15% or extending the feeding period to 14 d. Food deprivation was more effective in counteracting the heat-induced rise in body temperature than a dietary Ca deficiency. Heat-induced changes in body temperature, Ca+2, inorganic phosphate and blood pH were highly correlated (P 0.001). The change in Ca+2 followed a pattern similar to that of changes in body temperature, but changes in inorganic phosphate seemed to be more indicative of changes in pH. Control birds fed 0.90% Ca exhibited the highest changes in Ca+2 and body temperature values. Feeding Ca-deficient diets reduced changes in both Ca+2 and body temperature. Unfed birds, regardless of dietary Ca level, showed the lowest changes in Ca+2 and body temperature. The results suggest that during heat stress, the increase in body temperature is inversely related to the chickens' ability to maintain blood Ca+2