Phenotypic Variation and Relationships Between Fatty Acid Concentrations and Feed Value of Perennial Ryegrass Genotypes from a Breeding Population

Fatty acid (FA) concentration and composition of forage has recently gained interest due to potential opportunities for improving FA profile of ruminant products (meat and milk). Twenty perennial ryegrass genotypes from an experimental breeding population and four genotypes from an experimental mapping population were used to assess (1) genotypic variation, and (2) associations between FAs and other important chemical constituents (i.e., protein, carbohydrate and fibre). Mean total FA (TFA) concentration was 23.8 g kg−1 DM, ranging from 14.5 to 33.8 g kg−1 DM; 89% to 95% of which was comprised of six individual FAs, namely, palmitic acid (C16:0), trans-3-hexadecenoic acid (C16:1Δt3), stearic acid (C18:0), oleic acid (C18:1Δc9), linoleic acid (C18:2Δc9,12) and α-linolenic acid (C18:3Δc9,12,15). Mean crude protein (CP), water-soluble carbohydrate (WSC), neutral detergent fibre (NDF) and acid detergent fibre (ADF) concentrations were: 133, 188, 447 and 240 g kg−1 DM, respectively. Genotypes from the mapping population differed for: WSC (p = 0.015), C16:0 (p = 0.034), C18:0 (p < 0.001), C18:3Δc9,12,15 (p = 0.012) and TFA (p = 0.025). Genotypes from the breeding population differed (p < 0.001) for all measured components except CP (p = 0.078). Higher FA concentration was generally associated with higher CP concentration and lower WSC, NDF and ADF. Selectively breeding for higher FA concentrations may alter the overall feed value of perennial ryegrass, however further investigation is needed to fully understand the relationship between FA concentration and feed value and the possible implications for ruminant nutrition.