Effect of dietary iodine on production of iodine enriched eggs

AIM: Objective of this study was to investigate the effect of different levels of iodine supplementation on iodine content of eggs in laying hens. MATERIALS AND METHODS: In the experiment, 135 laying hens (White Leghorn) of 55 weeks age were randomly distributed to 5 dietary treatments; each group contained 27 laying hens distributed in three replicates of 9 birds each. Diet T(1) was control basal layer diet without iodine enrichment in which iodine content (I(2)) was as per NRC recommendation. Basal diets were supplemented with calcium iodate (Ca (IO(3))(2)) at 5, 10, 15 and 20 mg/kg in T(2), T(3), T(4) and T(5) groups, respectively. The iodine content in the calcium iodate is 65.21%, therefore, the diets T(2), T(3), T(4) and T(5) contained 3.25, 6.50, 9.75 and 13.0 ppm iodine, respectively. The laying hens were fed the respective experimental diets ad libitum during the experimental period of 10-week. The iodine content of egg yolk and albumen was analyzed at the end of 5(th) and 10(th) week of the experiment. Economics of feeding for the production of iodine enriched egg was calculated at the end of the experiment. RESULTS: Increasing iodine levels in diet of hens from 0.45 to 13.0 ppm significantly increased egg iodine concentration, the highest concentration of egg iodine was observed in the group fed diet supplemented with 13.0 ppm iodine followed by those fed 9.75, 6.50, 3.25 and 0.45 ppm iodine in diet. There was no significant difference in the iodine levels of unboiled versus boiled eggs. Therefore, the consumers are ensured to receive the optimal levels of iodine from boiled iodine-enriched eggs. Among different diets, minimum and significantly lower feeding cost (Rs. per dozen or per kg eggs) was noticed in hens allotted T(3) diet (6.50 ppm I(2)). However, feeding cost of hens receiving 3.25 and 9.25 ppm I(2) was statistically (p<0.05) similar to control group (T(1)). Further, it was noticed that feeding cost (Rs. per dozen or per kg eggs) was significantly increased due to the inclusion of higher level of iodine (13.0 ppm). CONCLUSION: It was concluded that supplementing iodine at 6.50 ppm in layers diet was economically better for the production of iodine enriched eggs followed by feed iodine supplementation at 3.25 ppm as compared to control and other treatment groups.