Apparent Digestibility, Nitrogen Balance, Ruminal Microbial Nitrogen Production and Blood Metabolites in Thai Brahman Cattle Fed a Basal Diet of Rice Straw and Supplemented with Some Tropical Protein-Rich Trees (Report‪)‬

INTRODUCTION There are several species of multipurpose trees (MPTs) in tropical areas and some of them may be suitable for improving livestock production systems. A few in vivo studies have shown that the pod of the rain tree (Samanea saman) can be used as an energy and protein supplement for animal production systems in tropical climates, due to it being highly digestible and containing high total sugar (1830%) and protein (16-30%) (Jetana et al, 2007; 2008). In Thailand, Leucaena leucocephala is used as a protein supplement for improvement of beef cattle and dairy cow production. Usually, the leucaena is cut and sun-dried for use in cut and carry feeding systems. Sun-drying helps to alleviate the high anti-nutritional compounds found in the plant and restricting intake to less than 30-35% of total dry matter intake (DMI) also minimises the effects of these compounds on animal performance (Hammond, 1995; Yami et al., 2000). Mulberry (Morus alba) leaves are highly palatable and digestible (70-90%) to herbivorous animals and can also be fed to monogastrics (Nulchuen et al., 2003). Protein content in leaves and young stems, with a good essential amino acid profile, varies from 15-28% depending on variety (Sanchez, 2000). Mineral content is high and no anti-nutritional factors or toxic compounds have been identified (Sanchez, 2000). Cassia siamea Lam. (Fabaceae) is a medium sized legume tree in the tropics. Its leaves contain high levels of protein (FAO, 1999). Cutting and drying (cut and carry; sun-dried) these leaves, as is commonly done with leucaena, and mixing with other ingredients may be another useful way improve livestock production.