Influence of particle size and calcium source on production performance, egg quality, and bone parameters in laying ducks

The ininot sign,uence of calcium source (limestone and oyster shell) and particle size (< 0.1 mm; 0.85 to 2 mm) on laying performance, egg quality, and bone properties were examined in laying ducks by a 2 x 2 factorial arrangement of treatments. Longyan females (288) with similar BW at 24 wk of age were randomly allotted into 4 treatments, each with 6 replicates of 12 individually caged birds and studied over the following 12 wk. Particle size affected egg weight and feed conversion (P < 0.05). Large particle size increased shell breaking strength, albumen height, Haugh unit, and shell content of phosphorus and magnesium (P < 0.05), but had no effect on egg shape, yolk color, shell thickness, or the weight proportion of shell. There were no effects of particle size on tibial properties: dry defatted weight, calcium content, or breaking strength. Limestone increased albumen height, shell content of calcium and phosphorus, and the breaking strength of tibia (P < 0.05). It is concluded that limestone with a large particle size provided for superior productive performance, egg quality, and bone characteristics and is more suitable than oyster shell for practical applications.