Effect of Feeding Iodinated Casein on Production and Health of Milking Cows

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Abstract
Two feeding trials using Holstein and Jersey milking cows in which iodinated casein (thyroprotein or Protamone) was fed gave results similar to those previously reported except that certain cows showed excessive losses in body wt. and showed increases in body temps. In a reversal trial milk yields and fat % showed significant increases. The same trend was shown in a continuous trial for the first 5-6 weeks, after which the control cows excelled those receiving iodinated casein. 3 of the 6 cows used in the reversal trial (all Holsteins) showed excessive body wt. losses of 98, 106, and 154 1b. while receiving 15 gms. of the synthetic thyroprotein daily. In the continuous trial an adjustment in the initial rate of 1.5 gms. per 100 lb. of live wt., in line with live-wt. changes as detd. from weighing animals periodically, seemed to prevent the excessive losses as experienced in the reversal trial. Increases in body temp., which were apparently due to iodinated casein averaged for the 2 periods of the reversal trial 0.14[degree]F and 1.27[degree]F; in the continuous trial it was 0.68[degree]F higher. Body temps. of cows were closely correlated with atmospheric temps., with those cows receiving iodinated casein appearing to be more sensitive to atmospheric changes than were the control cows. Pulse rates of cows receiving iodinated casein excelled rates for control cows by an average of 10 and 13 beats per minute, respectively, in the 2 trials.