Exercised Ponies Fed Hay and Three Concentrate Feeds: Apparent Digestibility, Nutritive Value, Observed Versus Calculated Digestible Energy and Behavior

Four ponies were fed at 2% bodyweight as dry matter (DM) per day, hay, or a 50:50 mix of hay plus one of three complementary feeds (Spillers HDF Power Cubes, Winergy Equilibrium High Energy, and Buckeye Nutrition EQ8 Gut Health), in a 4 × 4 Latin square design. The complementary feeds contained (g/kg DM) 168-209 g starch, 57-98 g oil, 131-134 g crude protein (CP), and 300-345 g neutral detergent fiber (NDF). Corresponding hay values were trace, 16, 58, and 620. A 5-day nutrient balance period followed 18 days adaptation. Ponies were exercised for an average of 45 minutes/d according to a strict protocol. Digestibilities of DM, gross energy (GE), N, and NDF were similar for the complementary feeds, averaging (±SD) 0.74 ± 0.006, 0.74 ± 0.015, 0.76 ± 0.026, and 0.52 ± 0.079, respectively. Apart from NDF, complementary feed digestibilities were significantly higher than those of the hay which were DM, 0.43; GE, 0.40; CP, 0.45; and NDF, 0.41. Feed digestible energy (DE) contents were also calculated from their chemical composition. After adjustment for oil content, DE values of the complementary feeds were within 5.5% of observed values, indicating this was a useful method for predicting the DE of such feeds for exercised ponies. Intakes of the mixed hay:complementary feeds all exceeded the ponies requirements for DE, digestible crude protein, and CP, but the hay provided only 0.76, 0.6, and 0.74 of these requirements. There were no apparent effects of feeding any of the complementary feeds on pony behavior when either stabled or exercised.