Chemical Composition And Ruminal Fermentation Characteristics Of Tropical Fodder Trees (Cratylia Argentea, Calliandra Calothyrus And Morus Alba)

Goat production in the tropics relies on both native and or improved grass pastures. Experiences in Puerto Rico, however, indicate that nutritional constraints to improved goat production are due to a scarcity of feed supply, low feeding value of tropical grasses and reduced efficiency of utilization of available feed resources. Exploitation of fodder trees as browse plants can be an effective strategy to improve goat nutrition. Little information, however, is available on the use of fodder trees in goat feeding. The objectives of this study were to determine the chemical composition, in situ dry matter degradability (ISDMD), forage degradability rates (kd) and protein solubility fraction of three fodder trees [Calliandra calothyrus (Powderpuff; CC); Cratylia argentea (Cratylia; CA); Morus alba (Mulberry; MA)] and a tropical grass hay mixture (TGHM). Twigs of each fodder tree were clipped, oven-dried and ground in a Wiley mill to pass a 1-mm screen. Samples were analyzed for crude protein (CP), organic and inorganic matter (OM and IM), and cell wall components [NDF, ADF and hemicellulose (HC)]. Data were analyzed using the GLM procedure of SAS. The ISDMD study was conducted in a fistulated Holstein cow maintained on a grass diet utilizing the suspended nylon bag technique. Triplicates samples (5g) were incubated for 0, 6, 12, 24, and 48 hrs and analyzed for degradation rates and dry matter disappearance. Data were analyzed using a non linear regression procedure, y = a + b ( l - e ~ c l), where a = soluble fraction, b= degradable fraction, and c= rate of degradation, and t = incubation period. Protein solubility percentages were estimated by protein content difference after placing samples in nylon bags in fistulated cow. Crude protein was higher (P<0.05) for MA (21.0%) than for CC (16.27%), CA (14.65%), and TGHM (4.69%). There were a difference (P<0.05) for OM among the studied forages (CC 91.89; CA 88.49; MA 86.66 and TGHM 93.51%). The TGHM had high NDF and ADF values (74.31 and 55.59, respectively) compared to the others forages species. The NDF and ADF values were: 52.66, 40.67 (CA); 47.51, 37.26 (CC) and 28.50, 15.38 (MA). Protein solubility percentages were 25.79, 35.52, 47.72, and 19.85 % for CA, MA, CC and TGHM, respectively. After 48 hrs of ruminai fermentation in situ dry matter disappearance values were 41.85, 45.52, 91.75, and 36.56 % for CA, CC, MA and TGHM, respectively. Ruminai kd values of DM degradability were calculated for CA (.005), CC (.011), MA (.003) and TGHM (.01). The higher protein solubility was observed for MA (47.72%), and as expected the lower for TGHM (19.85). The higher CP % and ISDMD for the fodder trees evaluated compared to the TGHM indicates its potential use as supplement for small ruminants diets based on tropical grasses.