The calcium balance in laying hens evaluated by ileal method

Abstract

The metabolism of calcium (Ca) in poultry is more intense than in mammals. Highly productive laying hens excrete with eggs during the productive cycle the amounts of Ca 20-30-fold higher than its total pool within the body. Since the evaluation of mineral exchange requires balance trials there are certain difficulties in the determination of the amounts of Ca in feces which was not absorbed in the digestive tract and which entered the feces from the water-excretory system. The aim of the study presented was the determination of Ca balance in laying hens using the method of ileal availability. The experiment was performed on six Hisex White hens (20-28 weeks of age) with ileal fistulae. The assimilation of Ca assessed using the ileal method was higher by 14.2% in compare to control treatment. At lower dietary Ca level (3.0%) the assimilation rate was lower by 31.7% in compare to the control period while increased dietary Ca level (4.6%) enhances Ca balance and improves its assimilation to 29.0%, below the optimal assimilation level. This low Ca availability in the digestive tract resulted in its higher excretion with feces. Concentration of Ca in blood serum grew by 55.0% with the increase in dietary Ca level. The decrease in the latter to 3.0% increased concentration of total protein in blood by 18.7%, glucose by 28.6% while concentration of phosphorus decreased more than 2-fold evidencing the general enhancement of mineral metabolism.