Fatty acid composition and nutritive value of twelve cultivars of perennial ryegrass

A comparison was made of the fatty acid composition and nutritive value of twelve cultivars of perennial ryegrass (Lolium perenne L.) differing in heading date and ploidy level. The cultivars were sown in triplicate plots and three sequential cuts of herbage were taken at 20-d intervals during the late spring and early summer to describe the fatty acid composition and other measurements of nutritive value. Differences between cultivars were recorded for DM content (P < 0·01) and concentrations of gross energy, neutral-detergent fibre (NDF) and ash (P < 0·05). Diploid cultivars had a higher DM content and concentration of NDF (P < 0·01) than tetraploid cultivars whilst late-heading date cultivars had the lower NDF (P < 0·05), ADF and ash (P < 0·01) concentrations. There was variation between cultivars in fatty acid composition. Diploid cultivars had a higher concentration of C18:0 (P < 0·01) and C18:1 (P < 0·05) than tetraploid cultivars and late-heading date cultivars had the highest concentrations of total fatty acids, C16:0, C18:2 and C18:3 (P < 0·05). This was predominantly due to the cultivar Tyrella which is a diploid, late-heading cultivar. The study showed that some variation exists between perennial ryegrass cultivars in concentrations of polyunsaturated fatty acids, which may present opportunities to select for this trait, but further research on the developmental stages and degree of leafiness of cultivars is first required.