Use of high pressure liquid chromatography (HPLC) for the determination ofcda-tocopherol levels in forage (silage/grass) samples collected from different regions in Ireland

First, second and third cut grass silage samples were collected from eight regions around Ireland (184 samples in total) and analysed for vitamin E co ntent. Fresh grass samples were also collected at one site in Co. Cork and analysed for alpha -tocopherol content. The concentration of alpha -tocophe rol [mug/g dry matter (DM)] was determined using high performance liquid ch romatography analysis. A wide variation in alpha -tocopherol levels in sila ge samples was found, alpha -Tocopherol levels in first, second and third c ut silage samples ranged from 4.9 to 20.8, 4.4 to 13.0 and 1.3 to 3.9 mug/g DM, respectively. The mean Values of alpha -tocopherol in first, second an d third cut silage samples were 11.3+/-0.9, 9.7+/-0.7 and 2.3+/-0.5 mug/g D M, respectively. There was no significant difference in a-tocopherol levels between first and second cut silage samples. However, third cut silage sam ples had significantly (P<0.05) less <alpha>-tocopherol compared to first a nd second cut samples. There was no decrease in alpha -tocopherol levels in silage samples following storage at -20 degreesC for 2 months. Fresh grass samples were classified as pasture grass, meadow grass (consisting of 20% Bromus spp and 80% Holcus spp, hedgerow grasses (predominately Dactylis glo merata L.) and white or red clover. Pasture grass had significantly (P<0.05 ) higher <alpha>-tocopherol levels than other grass types analysed. Meadow grass had significantly (P<0.05) higher <alpha>-tocopherol levels than clov er or hedgerow grasses. alpha -Tocopherol concentration in the different gr ass types decreased in the order: pasture grass > meadow grass > hedgerow > white clover > red clover. (C) 2001 Elsevier Science Ltd. All rights reser ved.