Effects on Economy and Efficiency of Milk Production when Thyroprotein Is Fed for a Short Period of Time to Milking Cows

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Abstract
Three expts. involving 47 cows were performed, in which thyroprotein was fed for 60 days to determine its effect on milk production, body wt, butterfat test, roughage consumption, efficiency of production, and monetary returns. Data from the exptl. and post exptl. feeding periods were combined in order to make a proper evaluation of the over-all effect of thyroprotein feeding on total milk produced, efficiency of production, and monetary returns. The avg. increase in milk production was about 20% but the response was variable between individual cows. In most cows production decreased to a lower than normal level after thyroprotein was withdrawn from the ration. When only a short post-exptl. period was included in the considerations there was an advantage in total fat corrected milk (FCM), efficiency and monetary returns for the cow fed thyroprotein, but the inclusion of a longer post-exptl. period of decreased production lessened this advantage considerably. Thyroprotein feeding caused an avg. increase in fat test and a large decrease in body wt. which was alleviated by feeding extra grain.