Intakes and in vivo apparent digestibilities of four types of conserved grass forage by ponies

The intakes and in vivo apparent digestibilities (AD) of four forages: hay (H), haylage (HY), big-bale silage (BB) and clamp silage (CS), were investigated in Welsh cross pony geldings (live weight (LW) ca. 330 kg). The trial was a 4 ✕ 4 Latin-square design with diets offered at 1•65 g/kg dry matter (DM) per100 kg LW per day, in two equal meals. Food and faecal samples were analysed for DM, organic matter, crude protein (CP), gross energy, calcium (Ca), phosphorus (P), magnesium (Mg) and non-starch polysaccharide (NSP) composition and content. Significant differences (P < 0·05) in DM intakes (DMI) g/kg M0·75 were recorded between foods, where HY = BB = H > CS. For all measurements AD was significantly (P < 0·05) higher for BB and CS than for H, with HY being intermediate in all but digestibilities of Ca and Mg. Digestibility of NSP of BB and CS were significantly (P < 0·05) greater than for H and HY. The digestible energy (DE) of H, HY, BB and CS were 5·75, 9·09, 9·83 and 11·98 MJ/kg DM respectively, which coupled with the corresponding DMI resulted in all foods but H meeting the theoretical daily DE requirements of the ponies. Similarly, theoretical digestible CP requirements were met on all diets except H. NSP fractions accounted for 0·5 of daily DE in both H and BB, which were significantly (P < 0·05) higher than for CS and HY at 0·4 and 0·2 respectively. These results indicate that CS, BB and HY are readily digested by ponies and thus offer suitable high-energy alternatives to hay in horse rations.

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