BIOAVAILABILITY OF FOUR CALCIUM SOURCES IN THE SECOND CYCLE EGG-PRODUCING HEN

Summary In the second cycle of laying hens, egg production and quality decrease. This is mainly due to decreased absorption of calcium from the gastrointestinal tract. Hence, serum concentrations of calcium tend to decrease and are compensated through bone reabsorption. There are several sources of calcium with different solubilities and absorption rates. The choice of one of them may be of importance for the referred second laying-cycle in hens. Hence, relative F (Fr) of four sources of Ca were evaluated in 300 Bovans-White 85-week-old hens. Animals were randomly assigned to five groups as follows: control-group receiving base-line doses of calcium carbonate as required by this hens' linage (GC); GCca-group which received additional calcium carbonate; GFtc-group dosed with tricalcium phosphate; GLgc-group which received calcium lactate-gluconate, and GCcaCp-group which received calcium carbonate plus 10 μg of capsicum oleoresin (COr). Each hen was orally dosed with 1 g of Ca-equivalent by probe, and serum Ca was quantified at predetermined times. Ca-kinetic behavior was characterized by calculating: maximum serum concentration (CMAX); time to achieve CMAX (TMAX); area under the concentration curve vs. time (AUC0-24). Fr as compared to GCca were calculated. GLgc and GCcaCp had the greatest CMAX and Fr values i.e., 34.7 and 37.2 μg/dL for CMAX and 109.6 and 112.9 % for FR, respectively, and they were statistically indistinguishable between them (P