Development of a method to determine carotenoid composition of fresh forages

Abstract

Due to the limited interest in carotenoids in ruminant diets until recently, analyses of forages are often incomplete, focusing mainly on β-carotene and lutein. Carotenoid composition of green forage from middle mountain meadow was analyzed by HPLC after extraction and elimination of chlorophylls by mild saponification. This method of analysis uses two C 18 columns in series with a quaternary gradient system. Our method allowed, for the first time, the identification and quantification of several xanthophylls other than lutein (i.e., violaxanthin, antheraxanthin, epilutein) in chlorophyll-free extracts from carotenoid-rich forage. The intra-day (3.5-7.5%) and inter-day (1.2-3.5%) coefficients of variation are suitable for routine determination of carotenoids in green forage. This method could also be used in metabolic studies of these micronutrients in ruminants.