Chopping Hay Before Feeding Does Not Influence Fecal Particle Size, Blood Variables, or Water Intake in 3-Year-Old Arabians

Previous work suggested that feeding chopped roughage, rather than long-stem, may influence thermoregulation during prolonged exercise, potentially by reducing hindgut particle size, thereby influencing water dynamics. This study aimed to determine if chopping hay affects fecal particle size (FPS), packed cell volume (PCV), plasma total solids (TS), and fecal dry matter (FDM). Six 3-year-old Arabians were divided into two groups and initially, for acclimation, fed either long-stem alfalfa hay or the same hay chopped (3-6 cm length) for a week each in a cross-over design; in weeks 3 and 4, this cross-over repeated. On days 6 and 7 of weeks 3 and 4, water consumption was measured over 48 hours, feed intake time was recorded, and PCV plus TS were measured at 0, 30, 60, 90, 120, 150, and 180 minutes after feeding. Fecal samples were collected each morning during weeks 3 and 4 to determine FDM and FPS. Packed cell volume and TS increased over the 3-hour sampling period (P < .01), but chopping the hay had no effect on the hay intake time, PCV, or TS. Water consumption and FDM did not differ between treatments (P = .9; P = .24) and there was no effect of treatment on FPS (P = .50). Only 10% of the fecal particles did not pass through the largest 2.36 mm sieve and 44% passed through the 150 μm sieve, suggesting marked reduction in particle size during the digestive process regardless of original hay intake length. Chopping hay did not have an impact on measured variables including FPS.