Dairy farmers in most countries in southeast Asiaare forced to feed low quality roughage such as ricestraw together with an expensive concentrate in the dry season to dairy cows [1]. Agriculturalcrop-residues and by-products from agro-industry such as rice straw, sugarcane tops and corn stover are an important source of feed for ruminants and commonly used in cattle and buffalo diets in Thailand [2]. Vinasses is a co- product generated by the fermentation of molasses to obtain alcohol [3].Hadalgo [4] reported that vinasses have been used as a liquid in animal feeding. Mohd Najib et al. [5] reported that fodder conservation had the main objective of ensuring feed availability during periodsof scarce feed supply. In most dairy cow feeding in Thailand, pineapple waste silage and leaves from baby-corn canning factories and sweet corn waste silage have been used for cattle feeding [6]. The objective of this experiment was to determine the
silage by-products part of roughage source for lactating dairy cows and compare with other roughage
sources on rumen fermentation.