Effect of different levels of organic chromium on performance and egg quality characteristics of laying hens reared at high stock density

In order to study theeffects of various levels of organic chromium on performanceand egg quality characteristics oflaying hens reared at high stock density, an experiment was done using twolevels of density (three and five birds per cage) and four levels of organic chromium (0, 300, 600and 900 ppb) with 192 laying hens (Hy-line W-36) in a completely randomizeddesign with factorial arrangement of 4×2 with six replicates. The results showed that dietarysupplementation of chromium at normal and high stock density had notsignificant effect on performance of layers. Egg weight significantly increasedat levels of 600 and 900 ppb (56.96 and 56.91 g) and feed intake significantlydecreased (99.34 vs. 105.05) in birds reared at high stock densitycompared to the birds reared at normal stock density (P<0.05). In thefirst four, second, and whole periods of sampling, dietary inclusion ofchromium at normal and high stock density, increased significantly egg yolkcolor and egg shell strength compared to the control (P<0.05). Dietarysupplementation of chromium at normal and high stock density had notsignificant effect on blood parameters and tibia charachteristics of layers. Ingeneral, the results of the experiment showed that by increasing dietarysupplementation of chromium at high stock density up to 900 ppb, egg yolk colorand egg shell strength significantly increased in laying hens.