Iodine Deficiency in Goats?


 A goat owner said to me:  “This kidding season, the newborn buck kids were unusually large while the doe kids were unusually small.   I have  heard that this could be caused by a deficiency of iodine.  Have youl ever heard of anything like that?"  I had not.  

     But, I did some internet browsing and checked a couple of books on goat medicine, and could find nothing on sex related birth size disparity in newborn kids. 

     Ater reporting this to the goad keeper, she sent me a reprint entitled, “RECORDS OF NUTRITIONAL FACTORS IN FERTILITY OF GOATS” — posted to my blog site as   http://www.dochollidaysblog.com/article-index/records-of-nutritional.html

     This paper summarized over a decade of fertility records in  an Australian goat herd from the late 1960’s and 1970’s.  The herd experienced the same size disparity in newborn buck and doe kids as stated in the original question. 

     The problems were apparently associated with feeding clover or alfalfa hay along with a mineral supplement containing a generous limestone base.    It was though the phyto-estrogens in the legume hay (containing goitrogens which depress the production of the hormone thyroxin)  along with the high calcium content of the hay and mineral limited the uptake of iodine by the thyroid gland.

      The elimination of clover hay and ground limestone from the diet resulted in a remarkable improvement in fertility but the sex ratios still favored males 1.4 to 1. This ratio was improved when iodized salt and copper-cobalt licks were offered.  

      Classic signs of Iodine deficiency in newborn goats are being born dead, abnormal hair coat, and enlarged thyroid glands, located in the throat area — goiter.  Since this lady’s goats showed none of these signs, I doubt if an iodine deficiency was involved. 

     Some folks recommend giving oral doses of Lugol’s iodine as a  supplement.  I think this is a bad idea.  It is difficult to know the exact amount needed by individual animals.  Force feeding could lead to an excess of iodine, which can also cause thyroid gland problems. 

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     If you suspect your animals are low on iodine and need a supplement,  you could provide a free  - choice source of iodized salt AND a free-choice source of regular white salt.  This allows animals to match their individual needs without  over-loading them.

     In the last analysis, the best plan is to provide a full-course, cafeteria-style  mineral feeding program. 



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