Natural forages are an important part of the diet of cattle in Cambodia, but their nutrient value, particularly in terms of macro-minerals, may be inadequate, leading to potential mineral deficiencies in grazing cattle.

This thesis compared the nutrient composition of six forage types (rice bran, rice straw, para grass, cassava foliage, leucaena leaves, water hyacinth leaves) from two regions in Cambodia against faecal and urinary excretion of macro minerals by cattle. The analyses showed that Ca and P levels varied markedly between the different forages and that several of the commonly used forages in Cambodia have a mineral composition that does not cover the requirements of cattle.In an experimental study examining the effects of different levels of dietary supplementation with sun-dried cassava foliage (Manihot esculenta) total dry matter

(DM) intake and nitrogen retention in cattle was found to increase with increasing intake of cassava foliage, but DM and fibre digestibility decreased. It was concludedthat cassava foliage is a good Ca source which compensates for the low Ca content in rice straw and para grass, but P deficiency appears to be exaggerated in cattle with higher cassava intake. Two experiments to find an appropriate way of using sugar palm syrup when preserving para grass showed that applying at least 2% (fresh matter basis) sugar palm syrup to para grass at ensiling improved the fermentation quality of the resulting silage compared with a rice straw with rumen supplement diet. Rumen pH was slightly lower and feed conversion more efficient in cattle consuming silage. Para grass silage was a good source of digestible nitrogen.

Keywords: cassava foliage, para grass/silage, sugar palm syrup, macro-mineral, intake,

digestibility, retention, fermentation quality.