Thyroprotein for Cows

T. .HE THYROID gland affects milk production. If the gland is removed from a cow, her milk decreases 75 percent. If it is put back, in the form of dried thyroid tissue or the synthetic hormone, thyroxine, her yield returns to normal. Both substances stimulate normal cows to give more milk and fat. The difficulty has been that dried thyroid tissue is too costly to feed cows, and if the total supply of the tissue were made available for feeding cows, we would have enough for only a few animals. Lately, how^ever, scientists have found a substitute. German scientists in 1938 found that the addition of iodine to proteins under certain chemical conditions makes a product that acts like dried thyroid tissue. The next step was taken by E, P. Reineke and G. W. Turner of the dairy department of the University of Missouri; they ascertained that iodine could be added to skim milk or casein, the protein contained in milk, under certain conditions, with a similar result. Further work disclosed that the actual hormone, thyroxine, w^as produced by the process. This material can be produced more cheaply and is even more active than dried thyroid. It does not lose potency in storage. It is known variously as iodinated casein, iodinated protein, thyrocasein, thyrolactin, thyroprotein, and by the trade name Protamone. Here we shall call it thyroprotein. Until recently it has been supplied only to experiment stations and similar research organizations for experimental purposes. Professors Reineke and Turner tested thyroprotein on 9 cows in their herd. When they fed 50 to 100 grams (3 to 6 ounces) of thyroprotein to each animal for 3 days, they had increases of 6.09 to 22.6 percent (an average of 8.59 percent) in milk production. In six of the nine trials in which fat analyses were made, an increase in the fat percentage was