Effect of acid or aluminum on growth and adrenal function in young chickens

Acid precipitation can have a harmful effect on aquatic birds, due in part to increases in aluminum availability. Young rapidly growing (broiler strain) chickens were used as a model to examine the effects of aluminum and acid on growth and circulating concentrations of adrenocorticol hormones. Two concentrations of acid (sulfuric acid) or aluminum (aluminum sulfate) or sodium sulfate were administered to a heavy (broiler) strain of chickens for 10 days (Days 4 to 14 of age). Additional treatment groups included a control diet either fed ad libitum or pair-fed relative to the chicks on the acid or aluminum diets. Compared with the chicks receiving the control diet ad libitum, growth (body weight) was reduced in chicks on the aluminum (high and low level), acid (high level), and sodium sulfate (high level) treatments and the respective pair-fed groups. Circulating concentrations of corticosterone (B) were elevated in the chicks receiving the high dose of aluminum and the respective pair-fed control when compared with the chicks which had free access to the control diet. Thus, the increase in plasma B appears to be linked to the low food intake and not to the A1 per se. Circulating concentrations of aldosterone were increased in the chicks receiving either the high dose of aluminum or the acid relative to chicks fed the control diet (both ad libitum or pair-fed controls). However, circulating concentrations of aldosterone were unaffected by either dose of sodium sulfate employed. Thus, the increase in plasma aldosterone appears to be specific to the metabolic acidosis created by A1 or acid. It is concluded that environmental acid may either directly or indirectly influence adrenocortical function. Moreover, the present study provides evidence for the independent control of circulating concentrations of corticosterone and aldosterone in the chicken.