Effect of Elemental Sulfur Supplementation on Rumen Environment Parameters and Utilization Efficiency of Fresh Cassava Foliage and Cassava Hay in Dairy Cattle (Report‪)‬

INTRODUCTION Feeding of dairy cattle in the tropics is often difficult because of deficiencies in feed supply, in both quality and quantity (Wanapat and Devendra, 1992). The use of rice straw as a feed in the dry season, in spite of its low nutritive value, has been a common feeding system, generally practiced by dairy farmers in the tropics when green forages are often scarce (Leng and Preston, 1983; Wanapat, 1994). Chemical treatment of rice straw to improve its quality has been reported (Wanapat et al., 1990). The development and utilization of cassava hay (cassava whole crop at a young growth stage, 3-4 months, harvested about 30-45 cm above ground, and sun-dried for 1-2 days until having a final dry matter of at least 85%, Wanapat, 1999; 2003) as an on-farm feed has been recommended as a possible solution to the lack of good-quality roughages during the dry season in the tropics (Wanapat et al., 1997). The cassava hay contains high protein, 20-27% CP, and condensed tannins, 1.5-4%. The use of cassava hay at 0.56 to 1.70 kg/head/d or about 0.1 to 0.5% BW was proved to be an excellent ruminant protein feed (Wanapat, 1999; 2003; Promkot et al., 2007). The use of cassava hay has been successfully implemented in several ways by either direct feeding or as a protein source in concentrate mixtures (Wanapat et al., 2000abc; Hong et al., 2003; Kiyothong and Wanapat, 2004; Wanapat et al., 2007; Chantaprasarn and Wanapat, 2008), in combination as a pellet of cassava hay, soybean meal and urea (Wanapat et al., 2006) or inclusion in a high quality feed block (Wanapat and Khampa, 2006).