Variations an α-Tocopherol and β-Carotene Concentrations in Forage Legumes and Grasses Harvested at Different Sites and Maturity Stages

Variations an α-Tocopherol and β-Carotene Concentrations in Forage Legumes and Grasses Harvested at Different Sites and Maturity Stages

Forage is a major source of natural α-tocopherol and β-carotene for dairy cows. This study examined vitamin concentrations of birdsfoot trefoil (Bft), red clover (Rc), timothy (Ti) and meadow fescue (Mf) at different sites, years and cutting dates. Mixtures of Bft+Ti, Rc+Ti and Rc+Mf were established at Skara (58°21’N; 13°08’E) and Umeå (63°45’N; 20°17’E) in Sweden. First-year leys were cut on three occasions in spring (Umeå 2005, Skara 2005 and 2007); one week before heading of timothy, at heading and one week after heading. Birdsfoot trefoil had higher α-tocopherol concentration at Skara than at Umeå in the first two cuts in 2005 (66 vs. 27 and 50 vs. 36 mg/kg DM, respectively) and had generally higher concentration than Rc. α-Tocopherol concentrations of Bft and Rc were 32 vs. 17 and 50 vs. 25 mg/kg DM at Umeå and Skara 2005, respectively, averaged over cuts. At Skara, α-tocopherol concentration decreased with later cutting date of Bft and grasses (P < 0.01). Birdsfoot trefoil had higher β-carotene concentration at Skara than at Umeå in 2005 (70 vs. 55 mg/kg DM) and higher concentration than Rc at Skara, when averaged over cuts (70 vs. 46 mg/kg DM in 2005 and 82 vs. 52 in 2007; P = 0.037). Grasses had higher α-tocopherol and β-carotene concentrations at Skara than at Umeå in 2005, when averaged over cuts (56 vs. 33 and 46 vs. 23 mg/kg DM; P < 0.001). Interactions between site, species and cutting date affected α-tocopherol and β-carotene concentrations in forages.