Effect of Different Forms of Iodine on Laying Hens

Abstract

White Leghorn hens were supplied with iodine from oyster shell, desiccated thyroid, sodium iodide, potassium iodide, iodo-salicylic acid, di-iodotyrosine and iodized olive oil. The birds were weighed at regular intervals and iodine determinations were made on samples of eggs from all the groups and on the feces and the thyroids and other tissues from some of the groups. The body weight, egg production and feed consumption was not adversely affected except in the case of the birds fed desiccated thyroid and in the case of the birds given sodium iodide when they received 16,000 γ of iodine per bird daily. The iodine content of the eggs varied from 3 to 1730 γ per egg. It differed according to the source of the iodine but corresponded only approximately to the iodine intake. Thus the iodine content of the eggs laid by birds fed potassium iodide, potassium iodate and di-iodotyrosine was significantly higher than the iodine content of the eggs laid by the birds fed iodo-salicylic acid. When iodo-salicylic acid was fed a higher percentage of the total iodine ingested was excreted then when di-iodotyrosine and potassium (or sodium) iodide was fed. These results indicate that iodine utilization by laying hens, in so far as it can be measured by the iodine content of the eggs and the excreta, depends upon the source as well as the amount of iodine given. The iodine content of the thyroid varied considerably but the differences were not statistically significant. The thymus also contained appreciable amounts with less iodine in the ovary (stripped of yolks), spleen and other tissues.