Effects of Vitamin D3 and Calcium on Productive Performance, Egg quality and Vitamin D3 Content in Egg of Second Production Cycle Hens

Abstract

This experiment was conducted to investigate the effect of supplementary vitamin D₃ on productive performance, internal egg quality, eggshell quality, apparent calcium digestibility and vitamin D₃ content in egg of second production cycle hens fed on different levels of calcium. A total of 140 second cycle brown-egg laying hens, aged 98 weeks, were randomly divided into 5 treatments with 4 replicates. The treatments consisted of diets containing 3.5%Ca and 2,000 IU of vitamin D₃/kg of feed (control), 3.5%Ca and 6,000 IU of vitamin D₃/kg of feed (treatment 2), 3.75%Ca and 2,000 IU of vitamin D₃/kg of feed (treatment 3), 3.75%Ca and 6,000 IU of vitamin D₃/kg of feed (treatment 4), and 4.0%Ca and 2,000 IU of vitamin D₃/kg of feed (treatment 5).  All diets were fed for 8 weeks. Thereafter, apparent calcium digestibility was studied for 5 days.  There was no significant difference in productive performance and internal egg quality among the dietary treatments (p>0.05). Thickness of eggshell increased with the addition of 6,000 IU vitamin D₃ in the diet containing 3.5%Ca or with the supplementation of calcium higher than 3.5% in the diet (p<0.05). The hens fed on 4.0%Ca in the diet produced eggs with greater specific gravity than the 3.5%Ca groups (p<0.05). Apparent calcium digestibility was not affected by the dietary treatments (p>0.05). Vitamin D₃ content in egg yolks increased with the content of vitamin D₃ in the diet (p<0.01). In conclusion, second production cycle brown-egg laying hens require dietary calcium higher than 3.5% or the addition of 6,000 IU vitamin D₃ in diet containing 3.5%Ca for eggshell quality improvement. Vitamin D₃ content in egg yolks can be increased at least 2.5 times by adding 6000 IU of vitamin D₃/kg feed to hens feed.