ACIDOGENIC CALCIUM SALTS AS Partial SUBSTITUTE FOR CALCIUM CARBONATE IN DIETS OF AGED LAYERS

Abstract

An experiment was conducted to investigate the effect of substituting calcium sulfate or calcium citrate for a part of dietary calcium carbonate on the performance of aged layers, eggshell quality, calcium retention, intestinal pH and blood calcium. One hundred and fifty Hy Line white (W-36) layers from 61 to 70 week of age were randomly distributed into five groups of 30 layers each. In four experimental groups each of calcium sulfate or calcium citrate was used to supply 0.3% or 0.6% of dietary calcium instead of calcium carbonate. Egg production was improved significantly by 4.1% and 3.5% due to adding 0.3% or 0.6% calcium in citrate form, while calcium sulfate had no effect. Average egg weight was not affected significantly by supplementing either calcium sulfate or calcium citrate into diets. Daily feed intake was reduced significantly by adding calcium citrate into diets while calcium sulfate had no significant effect. Feed conversion ratio significantly improved as a result of including calcium citrate into diets. The pH values of ileal content were reduced by supplementing calcium sulfate or calcium citrate into diets. Blood calcium levels of layers fed calcium citrate or calcium sulfate were slightly higher than the control. Calcium retention values of layers fed 0.3%(54.1%) or 0.6%(63%) calcium citrate were higher than that of control (49%). Egg shell quality was insignificantly improved by supplementing calcium citrate at 0.3% or 0.6% into the diets. Calcium sulfate at high level (0.6%) caused a slight impairment in egg shell quality.