Tocopherol and carotenoid levels in baled silage and haylage in relation to horse requirements

The content of α-tocopherol and β-carotene in a grass crop consisting of timothy (Phleum pratense), meadow fescue (Festuca pratensis) and couch grass (Agropyron repens) was analyzed before and after conservation as silage and haylage during 11 months in either small square (bale size 80 cm × 48 cm × 36 cm) or round bales (diameter 57 cm, height 68 cm). The purpose of the experiment was to study the effect of degree of fermentation on α-tocopherol and β-carotene content by varying dry matter (DM) levels via different wilting times. Silage wilted for 4 h to 300 g DM/kg (SIL), haylage wilted for 24 h to 500 g DM/kg (HL1) and haylage wilted for 34 h to 600 g DM/kg (HL2), all harvested as long stemmed forage, were made from the same field. Tocopherols and carotenoids were analyzed by high performance liquid chromatography (HPLC). Generally HL1 contained less α-tocopherol and β-carotene than SIL or HL2. There were no general effect of bale type on α-tocopherol and β-carotene content. SIL square bales and HL2 round and square bales contained 0.60 of initial α-tocopherol content and 0.86 of initial β-carotene content after ensiling, which were higher than SIL round bales and HL1 round and square bales containing 0.39 of initial α-tocopherol content and 0.33 of initial β-carotene content. Thus, there was no clear relation between degree of fermentation and content of α-tocopherol or β-carotene. The strongest correlation was found between lactic acid and β-carotene (0.44) and lactic acid and α-tocopherol (0.41), indicating that a good conservation process (lactic acid fermentation) may favour the preservation of α-tocopherol and β-carotene in conserved forage.