This work aims to evaluate the passage of digesta kinetics through the digestive tract and estimate the water and nitrogen balance in horses fed different levels of roughage in diets. Four crossbred yearling were used with age of 18 months, housed in individual stalls and exercised once a day. The present experiment was performed according to a 4 X 4 Latin Square design which each experimental period had 14 days for adaptation to diet and five days for fecal collection. Diets were composed by coastcross bermudagrass hay and concentrate, fed simultaneously and supplied twice a day, in proportions of 40:60, 60:40, 80:20 and 100:0. Kinetics of digesta passage was evaluated through the medium retention time (MRT), rate of passage (RP) and transit time (TT), using two external markers, mordant chromium in neutral detergent fiber (Cr-NDF) and Cobalt-EDTA (Co-EDTA). Water balance was evaluate according to water intake in natura and in diets and water excreted in urine and feces. Nitrogen balance was evaluated with daily intake and excreted nitrogen compounds. The MRT and RP of solid and liquid phases of digesta were 42.7 and 33.8 hours and 2.4 and 3.1 %/hours, respectively. Transit time had a negative linear effect in function of roughage inclusion in diets. Daily average water intake was 13.8 liters and water balance was 7.9 liters in diet with 40% of roughage and 1.8 liters in diet with 100% of roughage, showing a linear reduction with roughage inclusion in diets.
horse; nitrogen; rate of passage; water balance
