Effect of Various Dietary Calcium Sources on the Quality of Egg Shell in Summer

Abstract

Experiments were undertaken to investigate the effect of dietary calcium sources on the quality of egg shell in summer.140 cross-bred White Leghorn laying hens were housed from middle of June to first of October and fed corn-soy type diets with different calcium sources, such as oyster shell, fossil shell, calcium lactate and calcium carbonate and with 2 calcium levels, 2.75 and 3.5% Ca (as calcium additives, 0.69% Ca is dicalcium phosphate and the others are calcium carbonate and different calcium sources), respectively. Oyster shell and fossil shell diets contained 2.75% Ca, and 0.5% was administered by the corresponding calcium sources. Calcium lactate diet contained also 2.75% Ca and 0.15% was administered by calcium lactate. These calcium sources were added at the expense of calcium carbonate. Calcium carbonate diets contained 2.75% and 3.5% Ca.Fossil shell diet showed the highest values in shell thickness, egg shell strength, egg weight and plasma calcium concentration. Egg shell strength (P<0.1) and plasma calcium concentration (P<0.05) of fossil shell diet are significantly higher than other diets.Shell thickness and egg weight decreased in the hottest August and increased in October, however, egg shell strength was the weakest in the first September and improved quickly in October.There was no influence in egg production, feed consumption, feed convertion and body weight by dietary calcium sources and levels, except that calcium lactate diet showed rather lower egg production rate.