Digestibility of Water Oak and Shining Sumac leaves fed to Alpine goat wethers

R.C. Merkel¹, C. Toerien¹, T. Sahlu¹, and C. Blanche²

¹E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK, and ²Dale Bumpers Small Farms Research Center, USDA, ARS, Booneville, AR

Eight Alpine wethers (60.6 ± 2.43 kg BW) were randomly assigned to consume, free-choice, either Shining Sumac or Water Oak leaves as a sole diet. Leaves were collected and dried prior to feeding. A 14-d adaptation period was followed by a 4-d total fecal and urine collection. Chemical composition (%) of the fed tree leaves revealed similar levels of OM and N with higher concentrations of cell wall fractions, NDF and ADF, in Water Oak (OM 94 vs 96, NDF 55 vs 31, ADF 26 vs 35, and N 1.42 vs 1.54 for Shining Sumac and Water Oak, respectively). Body weight of wethers differed between treatments although, this difference did not affect DM intake (BW 64.3 vs 55.8, P < 0.10; DMI 60 vs 66 g/kg BW^.75, P > 0.10, for Shining Sumac and Water Oak, respectively). Daily intakes of DM (1.35 vs 1.35 kg), OM (1.29 vs 1.3 kg), ADF (0.38 vs 0.43 kg), and N (18.3 vs 22.6 g) were similar between treatments (P < 0.10). However, NDF intake was lower (P = 0.002) in goats fed Shining Sumac than in those consuming Water Oak (0.42 vs 0.75 kg). Daily fecal output of all components with the exception of N was higher (P < 0.05) in Shining Sumac- than Water Oak-fed goats. Differing fecal outputs, coupled with similar intakes of DM, OM, and ADF led to lower apparent digestibilities (%) of these components in Water Oak-fed animals (DM 82 vs 71, OM 83 vs 72, ADF 75 vs 44, for Shining Sumac and Water Oak, respectively). The higher NDF intake and fecal output for the Water Oak treatment led to NDF digestibility similar to that for Shining Sumac (70 vs 63% for Shining Sumac and Water Oak, respectively). Nitrogen digestibility was similar between treatments (64 vs 56% for Shining Sumac and Water Oak, respectively). In conclusion, the higher OM digestibility by goats of Shining Sumac than Water Oak implies that goats consuming Shining Sumac would have a better ability to maintain and(or) increase BW gain or body condition.