Thyroprotein in the Ration of Dairy Cattle. I. Its Influence on Milk Production, Fat Test, Heart Rate and Body Weight

Abstract

The daily feeding of 15 g. of thyroprotein to 8 cows resulted in an initial increase in milk production of 24.8% (7.9-36.2%). Of 7 cows in which lactation curves were projected, 4 remained above and 3 dropped below their estimated production. Thyroprotein feeding increased the fat content of the milk from 3.69 to 4.37%; fat test then decreased to 4.09% at which level it was maintained until the end of the feeding period. The solids-not-fat content of the milk increased and then decreased slightly during a 16-wk. feeding period. The avg. body wt. of 4 cows decreased from 1198 lbs. to 1126 lbs. and then steadily increased to 1175 lbs. Heart rate increased from 62 to 86 beats per min. and remained fairly constant for 12 wks.