INFLUENCE OF FORBS AND SHRUBS ON RUMINAL FERMENTATION AND DIGESTA KINETICS IN SHEEP FED A GRASS HAY STRAW DIET/

Four ruminally cannulated, Debouillet wethers were used in a 4 x 4 lat in square experiment to evaluate the influence of a forb mix, a shrub mix and alfalfa (ALF) hay on ruminal fermentation characteristics and digesta kinetics of a basal grass hay/straw (GH/S; 1.04% N) diet. The grass hay was mostly blue grama (Bouteloua gracilis) mixed with barley (Hordeum vulgare) straw. Wethers were fed either the GH/S mix (70:30) , GH/S:ALF (29:58:13), GH/S:forbs (26:54:20), or GH/S:shrubs (26:54:20 ). The forb component consisted of equal parts of scarlet globemallow (Sphaeralcea coccinea) and leatherleaf croton (Croton corymbulosus) wh ile shrubs were composed of equal parts of fourwing saltbush (Atriplex canescens) and mountain mahogany (Cercocarpus montanus). Ruminal pH, ammonia-N, as well as total VFA concentrations and molar proportions o f individual VFA did not differ among diets. Particulate passage rates tended (P > 0.10) to be greater for diets containing ALF, forbs or sh rubs (2.5, 2.9 and 2.8% h(-1)) than the GH/S diet (2.5% h(-1)). In sit u DM and NDF disappearance of a GH/straw (50:50) mix did not differ am ong treatments at most incubation times, except at 96 h when extent of both DM and NDF disappearance were greater(P < 0.05) in sheep fed eit her forbs or shrubs than in those fed other diets.