This study consisted of a series of in-vitro studies, surveys and in-vivo.The purpose of this study was to determine the use of cassava leaves as feed supplement on production performance and reproduction symptoms of milked buffaloes that reared traditionally. The material used in this study is the rumen fluid of buffaloes from Slaughterhouse Baleh Endah Bandung and feed supplements consisted of cassava leaves in pellet form. Variables measured were the characteristics of rumen fluid. The best results from this study are used for invivo studies in lactating buffalo producing of dadih with variables that, blood glucose and protein, milk production and quality , dadih production and quality and its organoleptic value, the health status of livestock by a decrease in faecal worm egg and reproduction symptoms of buffaloes. Results of in-vitro studies using 10% cassava leaf (Treatment B) as a feed supplement in pellets form on the characteristics of rumen fluid obtained normal rumen pH value is pH 6.0 -7.0 This condition can support the growth of rumen microbes work well in digesting the food fermentative and linked to the NH3, VFA, total bacteria, and KCBO KCBK that can support the fermentation process because the content is more complete nutrients. From in-vitro study was followed by the in-vivo studies.Results of in-vivo study showed that supplementation with feeding 1.5 kg / day can increase glucose and blood proteins buffaloes. The increasing of milk production is 0.96 ± 0.04 vs. 1.35 ± 0.03 kg/days with milk composition: moisture 82.90% ± 0.54, protein 5.68 ± 0.20%, fat 8.10 ± 0 , 20% and lactose 4.02 ± 0.24% and increase blood glucose and protein. The use of cassava leaves as much as 1.5 kg /day producing good quality of dadih with composition: moisture content 80.93% ± 0.38, protein 7.95 ± 0.68%, fat 9.51 ± 0.60%, Lactic Acids Bacteri 2.22 ± 0.19 (x10 5 ), acidity 1.22 ± 0019, viscosity of 2.68 ± 0.11Cpa. The use of cassava leaves on buffaloes can reduce worm eggs per gram of feces. While the use of 1.5 kg/days cassava leaves as feed supplement had no influence on the hormone prolactin, but influence the blood progesterone levels.