Using 24 diarrheic dairy calves under 8 weeks old, multiple fecal samples (4-12) were collected individually during the clinical advancing (max. 10 days) to evaluate the importance of fecal ammonia, lactate and volatile fatty acid (VFA) levels. Removing 3 calves not recovered during the sampling, 21 calves were grouped into under 3 weeks (< 3 wk; n=11) and 3-8 weeks old (3-8 wk; n=10). Data were divided into diarrheic and recovered feces with averaging in individuals. Diarrheic feces showed lower VFA and n-butyrate, and higher acetate proportions than recovered feces at <3 wk, but not at 3-8 wk. Diarrhea showed higher lactate, and lower ammonia and minor VFA (i-butyrate, valerate), which might reflect insufficiency in gut flora and fermentation.