Effect of selected plant species within biodiverse pasture on in vitro fatty acid biohydrogenation and tissue fatty acid composition of lamb

The effect of botanical diversity on supply of polyunsaturated fatty acids (PUFA) to ruminants in vitro, and the fatty acid (FA) composition of muscle in lambs was investigated. Six plant species, commonly grown as part of UK herbal ley mixtures (Trifolium pratense, Lotus corniculatus, Achillea millefolium, Centaurea nigra, Plantago lanceolata and Prunella vulgaris), were assessed for FA profile, and in vitro biohydrogenation of constituent PUFA, to estimate intestinal supply of PUFA available for absorption by ruminants. Modelling the in vitro data suggested that L. Corniculatus and P. Vulgaris had the greatest potential to increase 18:3 n-3 supply to ruminants, having the highest amounts escaping in vitro biohydrogenation . Biodiverse pastures were established using the six selected species, under-sown in a perennial ryegrass-based sward. Lambs were grazed (~50 days) on biodiverse or control pastures and the effects on the FA composition of m. longissimus thoracis (lean and subcutaneous fat) and m. semimembranosus (lean) were determined. Biodiverse pasture increased 18:2 n-6 and 18:3 n-3 contents of m. semimembranosus (+14.8 and +7.2 mg/100g tissue respectively) and the subcutaneous fat of m. l. thoracis (+158 and +166 mg/100g tissue respectively) relative to feeding a perennial ryegrass pasture. However, there was no effect on total concentrations of saturated FA in the tissues studied. It was concluded that enhancing biodiversity had a positive impact on muscle FA profile reflected by increased levels of total PUFA.