Continuous and Non-Continuous Feeding of Thyroprotein to Finishing Steers

Forty yearling Angus steers were used in an experiment to observe the effects of feeding thyroprotein (Protamone) throughout a 180-day feeding period or for only the first 84 days of the trial. The treatment groups were: Control (C)—a basal ground ear corn diet supplemented with soybean meal to contain approximately 11% crude protein, thyroprotein (T)—basal diet containing 0.367 g thyroprotein per kilogram of feed and fed for the 180-day feeding period, and thyroprotein-control (TC)—fed the thyroprotein (T) diet for the first 84 days and the control diet (C) for the remainder of the trial. Average daily gains for the 180-day trial were (C) 1.01 kg, (T) 0.90 kg, and (TC) 1.13 kilogram. The gains made by the thyroprotein group were (P<.01) lower than that of the TC group. Daily feed intake was increased (P<.05) in both the thyroprotein and TC groups. Feed required per unit of gain was higher (P<.05) for the thyroprotein group than for the other two groups. The increased gain by the TC group during the second period (85 to 180 days) resulted in an improvement (P<.05) in feed utilization as compared with that of both the control and the continuously fed thyroprotein group. Thyroprotein intake averaged 4.1 g/day for the thyroprotein group and 4.0 g/day for the TC group during the 84 days they were fed the thyroprotein diet. The longissimusarea was significantly (P<.05) lower in the thyroprotein group than in the control group. The thyroprotein group contained less body fat, as indicated by the fat over the rib and kidney fat. The effects of treatment on serum free fatty acid, cholesterol and urea nitrogen levels were discussed.