The effects of adding
copper or
methionine to low-
protein practical diets for turkeys were studied in two experiments involving an initial total of 2,496 day-old tom poults. In Experiment 1, 0 or 120 ppm
copper were added to diets providing about 75, 85, or 100% of the National Research Council (NRC, 1977) requirements for
sulfur amino acids (SAA) as supplemented by DL-
methionine. Experiment 2 involved four levels of
copper (0, 60, 120, and 240 ppm) added to diets containing three levels of SAA (75, 100, or 125%, NRC, 1977). Sixty ppm of
copper improved 8-week
body weight, while the effects of 120 and 240 ppm
copper were growth depressing but not beyond 8 weeks of age. Increasing the
methionine content of the diets to the 100% level for SAA (1977) consistently improved
weight gain of younger birds. The improved
body weight from
methionine additions for the older turkeys (16 to 24 weeks) however, was significant only in Experiment 1.
Copper did not influence the
methionine requirement in these experiments.