Biological availability of calcium in broiler chicks from different calcium sources found in Nigeria

An experiment was conducted to determine the biological availability of calcium (Ca) from six Ca sources available in Nigeria for broiler chicks and to investigate the effects of these sources on the performance of broiler chicks. The sources tested were calcium carbonate (428.4 g Ca/kg), bivalve shell (408.7 g Ca/kg), periwinkle shell (367.6 g Ca/kg), oyster shell (391.9 g Ca/kg), marble dust (398.5 g Ca/kg) and snail shell (360.5 g Ca/kg). One hundred and sixty eight day-old male broiler chicks were housed in electrically heated battery brooders and fed experimental diets that provided 10.0 g Ca/kg. A diet formulated without supplemental Ca that provided adequate levels of protein and energy and supplied 1.09 g Ca/kg was used as a basal. Experimental diets were balanced for Ca using different sources reduced to the same particle size using a mechanical grinder and then passed through a 500 μm sieve. Each Ca source was added in such an amount as to increase the total Ca fed to the birds to 10.0 g/kg of the diet. There was no significant effect (P>0.05) of the sources tested on feed intake, weight gain, apparent metabolizable energy, and apparent and true calcium availability. There were differences (P<0.05) in the effect of the sources on excreta soap formation. While the Ca sources tested did not affect (P>0.05) tibia bone length and diameter, this effect was significant (P<0.05) when bone ash was considered. While calcium carbonate that produced the least excreta soap is the most biologically available source for Ca, bivalve and periwinkle shells can be considered equally good Ca sources for use in poultry diets in Nigeria.