Influence of dietary calcium levels on the performance and egg quality of Canela-Preta free range laying hens

This study aimed to evaluate the zootechnical performance and egg quality of Canela-Preta free-range laying hens under diets with different calcium levels, while grazing on Bahia grass (Paspalum notatum). A total of 120 laying hens were housed in an experimental laying facility with access to pasture. The experimental design used was completely randomized in a 4x3 factorial arrangement (Ca X bird age), with dietary calcium levels of 2.3, 3.0, 3.7, and 4.4%, and bird ages of 28, 32, and 36 weeks. Each treatment had five replicates, with six laying hens per experimental unit. Parameters assessed were zootechnical performance, egg quality, and bone characteristics. The 2.3% calcium level met the laying performance requirements of Canela-Preta laying hens, between 28 to 36 weeks of age, representing the age of optimal feed conversion both per dozen and egg mass. Dietary calcium levels did not affect eggshell length, specific gravity, thickness, eggshell breaking strength, egg shape index, or Haugh unit. However, from 3.03% calcium inclusion onwards, yolk percentage decreased to 4.17% and eggshell percentage declined. Bone parameters were not affected up to 4.4% of calcium inclusion in the diets of Canela-Preta laying hens during the 28 to 32-week period of life.