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

Abstract

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.