Changes in Carbohydrate and Nitrogen Fractions and Digestibility of Forages: Maturity and Ensiling

Abstract

The effects of advancing maturity and ensiling on the carbohydrate and nitrogen fractions and in vitro digestibility were studied on freeze-ground fresh and ensiled samples of two forage sorghums (Pioneer 931 and RP-30F) and two corn varieties (Cargill 1089 silage corn and Cargill HS-50 high sugar corn) at five stages of maturity. Advancing maturity resulted in a significant (P < .01) increase in dry matter and hemicellulose and a significant (P < .01) decrease in crude protein and estimated total digestible nutrients (ETDN). The decrease in estimated digestible energy (EDE) and in vitro digestible dry matter with advancing maturity was significant (P < .05). Ensiled forage had a significantly (P < .01) lower soluble carbohydrate, EDE and EDTN content and a significantly (P < .01) higher acid detergent fiber, cellulose and lignin content than did fresh forage. The effects of advancing maturity and ensiling on composition of the structural constituents are discussed with reference to their effect on digestibility of forage plants.