Effects of dietary trace element supplementation on performance of laying hens and mineral content of egg yolk

In this experiment, 320 laying hens of Hy-Line W-36 strain were used in a 2 x 2 x 2 factorial design (eight treatments and eight birds in each pen). The treatments were 0 and 400 mg/kg iron salt, 0 and 450 mg/kg iodide, and 0 and 0.1 mg/kg vitamin B12. There were five replicates of each treatment combination and the birds were from 26 to 39 weeks old. The interaction of iron salt and iodide, the use of 450 mg/kg iodide and 0 levels of iron salt increased the iodide content of yolks. In the treatments with 400 mg/kg of iron salt combined with iodide and with 400 mg/kg of iron salt with 0 levels of iodine salt this caused a sharp decrease in the iodide content of the yolk. In the interaction of treatments containing iron salt and vitamin B12, the lowest amount of cobalt and the highest level of Iodide were observed at the 0 levels of both supplements, whereas the combined use of iron salt and vitamin B12 increased the level of cobalt and decreased the yolk iodine content. In the three-way effects between these salts, yolk iron and cobalt content increased, and the highest amount of Iodine was observed in the third treatment (without vitamin B12 and iron). Overall the use of iron salt, iodine, and vitamin B12 could improve the performance of hens and the composition of egg yolk.