466 A comparison of chaffhaye and alfalfa hay on digestibility and glucose metabolism in mature, stock-type horses

Objectives of this study were to evaluate the effects of Chaffhaye and alfalfa hay on digestibility and glucose metabolism in horses. Ten geldings (13.8 ± 8 yr, 553.2 ± 81 kg) were used in a cross-over design. Periods consisted of 21 d for adaptation, 1 d of blood collection and 4 d of fecal collection. Horses were fed at 1.9% of their BW/d (as fed) of either Chaffhaye (CHAF; 22.7% CP, 3.8% Crude Fat, 32.9% NDF, 25.35% ADF, DM basis) or alfalfa hay (ALF; 15.5% CP, 1.7% Crude Fat, 48.1% NDF, 40.1% ADF, DM basis). Blood collections were taken at 0, .5, 1, 2, 4, 6 h after a meal on day 22 and feces were collected every 6 h with a subsample frozen for analysis. Glucose (GLU) and insulin (INS) parameters were evaluated for area under the curve (AUC) and for the highest value (PEAK). Dry matter intake for horses receiving ALF was higher (P < 0.01) for OM, NDF, ADF, CP, NFC, WSC, and ESC. Starch and crude fat intake were higher (P < 0.02) for CHAF receiving horses. Water intake was insignificant (P = 0.41). There was a tendency for horses to have a lower insulin PEAK and AUC when fed CHAF (P < 0.11). Both GLU AUC and GLU PEAK were insignificant (P > 0.55). Wet fecal output per day was higher for horses consuming ALF (P < 0.01). Digestibility for ALF was higher for DM, OM, ADF and NDF (P < 0.01). Crude fat and CP digestibility was higher for CHAF (P < 0.02). NFC digestibility was not different (P = 0.84) between treatments. Alfalfa consuming horses had greater total tract digestibility of all measured parameters except CP and crude fat, and CHAF elicited a lower insulin response that could be helpful for metabolically-prone horses.