Value of Supplemental Lysine, Methionine, Methionine Analog, and Trace Minerals on High Urea Fattening Rations for Beef Steers

The results from three experiments designed to study the effect of adding L-lysine, DL-methionine, methionine hydroxy analog and trace minerals in high urea fattening rations for beef steers are reported. Zinc bacitracin was also tested in one experiment. Lysine, added singly or in combination with DL-methionine was of no benefit when added to a 32f0 supplement containing all natural protein. The addition of lysine to 40, 48, 56, 64 and 72% supplements made them equivalent to the 32% control containing all natural protein, when fed on a protein-equivalent basis. When 10 gms. of lysine were fed per steer daily, one lb. of 64% supplement was equal to 2.0 lb. of 32% supplement in two of the three experiments. Methionine improved the 64% supplement slightly, but not to the extent of that of lysine. Methionine analog was of no benefit at the 5-gm. level and gave a significant depression in rate of gain at the 10-gm. level. Trace minerals (Mn, Fe, Cu, Co, I and Zn) were of no benefit when added to either the 32% supplement or the 64% supplement. Zinc bacitracin fed at 80 mg. per head daily gave no improvement in daily gain or feed efficiency, but seemed to improve carcass grade.