Effects of betaine and choline on response to methionine supplementation to broiler diets formulated to industry standards

A study was conducted to evaluate the Met-sparing effects of the methyl donors, choline (CHO) and betaine (BET). Male broilers of a commercial strain were fed corn-soybean meal-based diets formulated to meet nutritional levels typical of top broiler producers. Diets were fortified with a complete vitamin premix devoid of CHO. In test diets, Met levels were as formulated, or less 0.05, 0.10, 0.15, or 0.20% Met. Within each Met level, diets received no supplemental CHO or BET or 1,000 mg of CHO/kg, 1,000 mg of BET/kg, or a combination of 500 mg each of CHO and BET/kg. This resulted in a 4 x 5 factorial arrangement with each of the 20 treatments fed to 4 pens of 60 birds for a 56-d feeding trial. Samples of birds were processed at 42, 49, and 56 d to determine parts yield and dressing percentage. Intestinal segments were evaluated for tensile strength at these same ages. The dietary Met level had no significant impact on BW at 14 or 56 d of age, but at 35, 42, and 49 d reduction of the Met content resulted in loss of BW. Feed conversion was not affected by the Met level at 14 d but was significantly affected by reducing the Met level at all other ages. Breast meat yield was reduced in a linear manner by reductions in Met supplementation. The CHO or BET supplementation had no apparent sparing effect on Met needs but did improve feed conversion at 35 and 42 d. There was a positive effect of CHO and BET on breast yield that was independent of Met levels; CHO was as effective as BET for this purpose. No effect of CHO or BET on intestinal strength was observed in the present study.