Digestibility, N balance and blood metabolite levels in Alpine goat wethers fed either water oak or shining sumac leaves.

Eight Alpine wethers (8-9 months of age, 27.5+/-1.10kg body weight (BW)) were randomly assigned to consume, free-choice, either shining sumac (Rhus copallina) or water oak (Quercus nigra) leaves as a sole diet. Leaves were collected and dried prior to feeding. A 14-day adaptation period was followed by a 4-day total fecal and urine collection. Chemical composition (%) of the fed water oak and shining sumac leaves revealed similar levels of OM (95.9 and 94.1) and N (1.54 and 1.42) but higher concentrations of cell wall fractions, NDF (54.8 and 31.2) and ADF (34.5 and 26.4), in water oak than shining sumac. Body weight of wethers differed between treatments, although this was not reflected in DM intake. Average daily intake values were 616g DM, 589g OM and 9.3g N. NDF intake was significantly lower (P=0.002) in goats-fed shining sumac than in those that consumed water oak (192 versus 330g). Daily fecal output of all components was higher (P<0.05) in water oak than shining sumac-fed goats. Apparent digestibilities (%) of all components were significantly lower in water oak than shining sumac-fed animals (DM 41 versus 63, OM 42 versus 64, NDF 24 versus 37, and N 27 versus 38). Urinary N excretion, N balance and concentrations of protein, plasma urea nitrogen (PUN) and glucose in the blood were similar between diets, averaging 2.6g N per day, 0.45g per day, 85.5mg/ml, and 14.1mg/dl, respectively. The results of this trial suggest that shining sumac is utilized better by goats than water oak. The use of dried leaves in this experiment may have led to possible negative effects on nutrient characteristics that animals consuming fresh leaves may not experience.