The Value of Thyroprotein in Starting, Growing and Laying Rations

THREE reports have appeared in recent years which suggested that thyroprotein might be a desirable ingredient for commercial broiler rations. These previous trials were done with small numbers for each dosage level and the chicks were reared in batteries rather than under practical farm conditions. Moreover, the statistical significance of the differences in response to treatment was not determined. Thus a need was apparent for a more extensive test of these findings under commercial production conditions with the attendant crowding, contact with intestinal discharges, and other normal brooding hazards. The work reported here is an attempt to provide further information on the value of thyroprotein when fed to broiler chicks under conditions approximating those in the field. REVIEW OF LITERATURE It is difficult to evaluate the literature on the effects of feeding thyroprotein to growing chicks. Not only have different investigators used different dosages, but the thyroprotein used has varied . . .