Submitted to: Tropical Grasslands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2000
Publication Date: N/A
Citation: Interpretive Summary: In many tropical countries tree legumes can provide an important feed source for ruminant production. Generally, tropical grasses are moderate to low in crude protein concentrations, which results in only moderate animal daily performance. The harvesting and feeding of leaves from tropical legumes to ruminants consuming tropical grasses can meet the daily ycrude protein requirements of the animal. This can greatly improve animal production and can be done very economically. Legume-tree species vary, however, in their content of leaf fiber and the presence of phenolic compounds. A comparison of leaves from the most available legume trees for their rate and extent of digestion is important when selecting legume trees as components of the animal diet. The crude protein concentrations ranged from 20.1 to 22.1 % in the leaves. We found the dry matter disappearance rate to be highest for gliricidia, intermediate for falcataria and lowest for calliandra. This rank was consistent with increasing soluble phenolic and proanthocyanidin concentrations. The extent of digestion was different for calliandra vs the other two, indicating that this legume tree was fermenting differently than the others. The higher dry matter residual left after 96 hours indicates that condensed tannins and phenolic compounds may have complexed with protein or cell wall carbohydrates resulting in an insoluble residue. This legume tree would not be the best choice for a nitrogen supplement in the ruminants diet.
Technical Abstract: Leaves of three tree legumes, Calliandra calothyrsus (C), Paraserianthes falcataria (f), and Gliricidia sepium (G), were harvested and divided into two portions for oven drying (OD) or freeze drying (FD) resulting in six experimental treatments COD, CFD, FOD, FFD, GOD, and GFD. The initial solubility, disappearance rate and extent (undegraded portion) of in sacco dry matter disappearance was calculated by a nonlinear model using dry mat disappearance values from ruminal incubation times of 0, 12, 24, 48, and 96 hours. Initial solubility was higher (P<0.01) in CFD than COD and lower (P<0.07) in FFD than FOD with G. sepium showing no difference. Disappearan rate was not affected by drying treatment. However, disappearance rates fo GOD (0.13 h-1) and GFD (0.14 h-1) were higher (P<0.001) than FOD (0.06 h-1) FFD (0.08 h-1). Both COD and CFD had a slow disappearance rate of (0.02 h- Freeze drying resulted in lower (P<0.001) undegraded portions in both CFD a aFFD than OD material while G. sepium was not affected by drying method. T use of oven-dried tree legume samples for digestibility estimation may underestimate their feeding value.