Chemical Composition, in vitro digestibility and in vitro VTA concentrations of New Mexico native forages

Comparative chemical composition, in vitro digestibility, and in vitro volatile fatty acid (VFA) concentration and molar proportions of current year's growth of twelve important native New Mexico forage species were evaluated. Volatile fatty acid data were collected on forage samples subjected to 12-h in vitro digestion using two different inoculum sources. Forbs and shrubs had higher ( P <0·05) total nitrogen and total available- nitrogen concentrations than grasses; however available nitrogen as a percentage of total nitrogen did not differ ( P >0·05) among grasses forbs and shrubs. in vitro organic matter digestibility (IVOMD) was higher (PKOOS) for forbs and shrubs than grasses for all incubation periods (24, 48, 72 hours). Lucerne hay and prairie grass hay inocula gave similar IVOMD results. Based on 24-h IVOMD divided by 72-h IVOMD, forbs were digested more rapidly than grasses ( P <0·05). Total VFA concentration and molar proportion differences among grasses, forbs and shrubs were small