Effect of thyroprotein feeding on dairy cows.

Abstract Sixty-three cows fed no thyroprotein averaged 7,265kg milk (308-day, mature equivalent compared to 7,237kg averaged by 63 cows fed 10g thyroprotein daily after 50 days postpartum. The maximum increase in milk production from thyroprotein feeding occurred during the first two weeks of feeding and amounted to a 7.0% increase over the control cows. From the 22nd to 42nd weeks of lactation milk production of thyroprotein-fed cows was less than that of controls. Milk fat tests were raised 0.41% (P Thyroprotein feeding resulted in marked reductions in body weight, barrel circumference, and body condition and marked increases in heart rates, respiration rates, and rectal temperatures. Cows and first-calf heifers receiving thyroprotein required more services per conception (P