PS8-1. Effect of Genotype, Harvest Date and Plant Anatomy on Nutrient and Phytochemical Profiles of Fenugreek Forage.

Abstract Fenugreek (Trigonella foenum-graecum L; FG) has shown potential as a high nutritive value forage. Recent research found that phytochemicals in FG have the potential to reduce enteric methane production and promote animal health. Therefore, it is important to understand the temporal and spatial distribution of nutrients and phytochemical compounds in FG to support the sustainability of the forage and cattle industries. The objective of this study was to determine the nutrient and phytochemical composition of different plant components at different growth stages under Western Canadian conditions. Two FG varieties (Tristar & Amber) were harvested by cutting whole plants to a stubble height of 5 cm at 7, 9 and 15 wks post sowing. Harvested plants were manually dissected to leaves, stems and seedpods with each fraction freeze-dried and analyzed for dry matter (DM), organic matter, crude proteins (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF) and water-soluble carbohydrates. Subsamples were also analyzed for fatty acid methyl esters (FAMEs), phytosterols, saponins, phenolics and alkaloids using GC-MS and HPLC. Overall, the two varieties did not differ in nutrient or phytochemical content. Leaves had the highest CP followed by seedpods and stems (p < 0.01), whereas stems contained the highest NDF and ADF followed by seedpods and leaves (p < 0.01). For both varieties, the leaf:stem ratio and CP content decreased (p < 0.01), while NDF and ADF increased (p < 0.01) in leaves, stems and seedpods from 7 to 15 wk. A total of 12 FAMEs, 8 phytosterols, 4 saponins, 9 phenolic compounds and 1 alkaloid were detected in FG, with the majority of these phytochemicals being present in all plant components. At 7 and 9 wks, leaves contained a higher (p < 0.001) concentration of these compounds than stems and/or seedpods. In contrast, at 15 wk, concentrations of saponins and the majorities of FAMEs, phytosterols and phenolics were higher (p < 0.05) in seedpods than in leaves and stems. All phytochemicals in leaves and stems decreased (p < 0.01) from 7 to 15 wk, whilst the majority of FAMEs, phytosterols and saponins in seedpods were higher (p < 0.05) at 15 than at 9 wk. Leaves are the primary site of phytochemical deposition in FG, with levels in seedpods increasing at maturity. Based on yield, nutritive value and the presence of bioactive compounds, optimal harvest time of FG for forage would be 7 – 9 wks after sowing.