Primary Audience: Nutritionists, Feed Manufacturers SUMMARY

Two floor pen trials were conducted to determine the digestible methionine + cystine requirement of male turkeys for the production period of 6 to 12 wk. The first experiment was conducted using 8 treatments with 6 replicate pens of 5 birds using a randomized block design. For the second experiment, 8 treatments with 4 toms per replicate were used. Digestible sulfur amino acid (SAA) levels ranged from 0.50 to 0.82 % of the diet in the first experiment and from 0.40 to 0.66 % in the second experiment. These levels were obtained by dose response using synthetic methionine in a low-protein diet. The other synthetic amino acids were added back to the low-protein diet at levels sufficient to provide growth similar to a positive control treatment. The positive control for each period was a standard corn, soybean meal, and pork meal diet based on NRC (1994) recommendations. The data were analyzed by analysis of variance followed by splined regression analysis to estimate the requirements. The SAA requirements for the 47-to 56-d growth period were determined to be 0.65 % and 0.66 % for body weight gain and feed conversion, respectively. The digestible SAA requirements for the 67- to 78- d growth period were determined to be 0.56% for both body weight gain and feed conversion