Corn Plant Maturity. II. Effect on In Vitro Cellulose Digestibility and Soluble Carbohydrate Content

Digestibility of corn plant cellulose by rumen microorganisms in vitro (IVCD) and the soluble carbohydrate content were determined on corn stalks and leaves at several stages of maturity, starting just prior to tasseling and ending just after a killing frost. IVCD of stalk cellulose declined until about 10 to 15 days after tasseling, after which it remained constant until frost. IVCD of leaf cellulose was higher than that of stalk cellulose and declined slowly but steadily throughout the entire period. The soluble carbohydrate content of corn stalk tissue increased rapidly from tasseling to a maximum in late August and thereafter declined to final maturity. The highest value found was about 500 mg. per gram of dry matter. Soluble carbohydrates in leaf tissue followed the same pattern, but were lower than in stalk tissue. Oven-dried samples had considerably less soluble carbohydrate than undried samples preserved in the frozen state. A major portion of the soluble carbohydrates disappeared in the ensiling process. Sufficient carbohydrates were present at all stages to promote proper ensiling. Ensiling did not appear to lower the IVCD.