title: Chronic heat stress and respiratory alkalosis: occurrence and treatment in broiler chicks.
abstract: The occurrence of respiratory alkalosis and potential benefit derived from treatment were examined in thermostressed 4-week-old broiler chicks. Blood pH was greater (P less than .05) in heat-stressed (32 C) panting birds (7.395) than either nonpanting (7.28) or birds raised at 24 C (7.28). Acute thermostress, obtained by elevating ambient temperature from 32 to 41 C over a 20-min period further elevated (P less than .05) blood pH to 7.521. Chronic heat-stressed broiler chicks suffer from intermittent respiratory alkalosis during panting; with acute heat stress, chicks pant continuously and suffer from alkalosis. Including .5% sodium bicarbonate (NaHCO3) in the diet of birds subjected to chronic heat stress enhanced body weight gain by 9% even though it tended (P less than .10) to increase blood pH in nonpanting birds. Adding .3 or 1% ammonium chloride (NH4Cl) to diets decreased blood pH (P less than .01) to 7.194 and increased (P less than .05) body weight gains by 9.5 and 25%, respectively. Effects appeared linear with NH4Cl dose to 1% NH4Cl, but 3% NH4Cl elevated weight gains by only 8% and precipitated blood acidosis (pH 7.09) in nonpanting birds. Supplementing the 1% NH4Cl diet with .5% NaHCO3 increased weight gains an additional 9%. Manipulating sodium: chloride ratios by addition of calcium chloride increased body weight gain 8% and slightly reduced severity of alkalosis. Data indicate that blood alkalosis limits growth rate of broiler chicks reared under chronic thermostress and that the respiratory alkalosis and weight gain depressions attributed to thermostress can be partially alleviated dietarily.
authors.forename: R G
authors.initials: RG
authors.lastname: Teeter
authors.forename: M O
authors.initials: MO
authors.lastname: Smith
authors.forename: F N
authors.initials: FN
authors.lastname: Owens
authors.forename: S C
authors.initials: SC
authors.lastname: Arp
authors.forename: S
authors.initials: S
authors.lastname: Sangiah
authors.forename: J E
authors.initials: JE
authors.lastname: Breazile
mesh_terms: D000472:Alkalosis, Respiratory / Q000178:diet therapy / Q000453:epidemiology / Q000662:veterinary*; D000643:Ammonium Chloride / Q000627:therapeutic use; D000818:Animals; D001639:Bicarbonates / Q000097:blood / Q000627:therapeutic use; D001774:Blood Chemical Analysis / Q000662:veterinary; D001835:Body Weight; D002122:Calcium Chloride / Q000627:therapeutic use; D002245:Carbon Dioxide / Q000097:blood; D002645:Chickens; D002908:Chronic Disease; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D011201:Poultry Diseases / Q000178:diet therapy / Q000453:epidemiology* / Q000503:physiopathology; D012964:Sodium / Q000627:therapeutic use; D017693:Sodium Bicarbonate; D013312:Stress, Physiological / Q000178:diet therapy / Q000503:physiopathology / Q000662:veterinary*
chemical_list: D001639:Bicarbonates; D000643:Ammonium Chloride; D002245:Carbon Dioxide; D017693:Sodium Bicarbonate; D012964:Sodium; D002122:Calcium Chloride