Abstract Kittivachra, R., Sanguandeekul, R., Sakulbumrungsil, R. and Phongphanphanee, P. Sample of eighteen farms also fed their cows with one of supplements: corn stem, soybean meal, or rice straw. All cows from these farms were Holstein-Friesian Hybrid. As supplemented high fiber diets, corn stem significantly increased the lactose quantities over soybean meal and rice straw (planned comparison, pvalue = 0.044). The study concluded that some high fiber diets, specifically corn stem, significantly contributed to the lactose quantities in raw milk. Factors affecting lactose quantity in raw mil