Evaluation of Pre-Cecal, Ileal Digestibility and Glycemic Response in Fistulated Horses Fed with Different Starch Sources

The objective of this study was to evaluate the coefficients of pre-cecal, ileal digestibility, and glycemic response in cannulated horses fed with different starch sources. Four male horses were used in a 4 × 4 Balanced Latin Square cannulated in the cecum, with 36 months of age and average weight of 350 kg. The horses were fed with hay and the following sources of starch in concentrates: 1) corn (C); 2) oats (O); 3) sorghum (S); and 4) corn/oats (CO). The experiment consisted of four periods of eighteen days each, being the first twelve days of adaptation and six days to collect samples. There was no difference in cecal and ileal digestibility of starch, CP, ADF, NDF and OM among diets evaluated. However, horses fed with oats diet had higher values of pre-cecal apparent digestibility of DM in relation at the horses fed to sorghum and corn/oats diets. The values of CF digestibility were higher for equines fed with oats and sorghum diet compared to corn/oats diet. The horses fed with corn/oats diet had lower plasma glucose concentrations 30 minutes before the supply and higher insulin concentrations 210 minutes after ingestion of the foods. The digestibility of nutrients in equine diets, in pre-cecal and pre-ileal evaluation, presents significant differences, depending on the starch source provided, oat, corn or sorghum. The plasma glucose concentrations are directly correlated with the digestibility of starch.