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 +/- 1.10 kg body weight (BW) ) were randomly assigned to consume, free-choice, either shining sumac (Rhu s copallina) or water oak (Quercus nigra) leaves as a sole diet. Leaves wer e collected and dried prior to feeding. A 14-day adaptation period was foll owed 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 wa ll fractions, NDF (54.8 and 31.2) and ADF (34.5 and 26.4), in water oak tha n shining sumac. Body weight of wethers differed between treatments, althou gh this was not reflected in DM intake. Average daily intake values were 61 6 g DM, 589 g OM and 9.3 g N. NDF intake was significantly lower (P = 0.002 ) in goats-fed shining sumac than in those that consumed water oak (192 ver sus 330 g). Daily fecal output of all components was higher (P < 0.05) in w ater oak than shining sumac-fed goats. Apparent digestibilities (%) of all components were significantly lower in water oak than shining sumac-fed ani mals (DM 41 versus 63, OM 42 versus 64, NDF 24 versus 37, and N 27 versus 3 8). Urinary N excretion, N balance and concentrations of protein, plasma ur ea nitrogen (PUN) and glucose in the blood were similar between diets, aver aging 2.6 g N per day, 0.45 g per day, 85.5 mg/ml, and 14.1 mg/dl, respecti vely. The results of this trial suggest that shining sumac is utilized bett er by goats than water oak. The use of dried leaves in this experiment may have led to possible negative effects on nutrient characteristics that anim als consuming fresh leaves may not experience. <(c)> 2001 Elsevier Science B.V. All rights reserved.