Effect of substitution of a proportion of the concentrate in grass silage/concentrate-based diets with extruded linseed on performance and meat quality of dairy bulls

While meat from ruminants (beef and lamb) has been shown to have high levels of saturated and low levels of polyunsaturated fatty acids (PUFA) (Wood et al 1999), the beneficial properties of beef include the lower n-6:n-3 ratio, particularly under grass-fed systems, relative to pork or poultry and the presence of appreciable quantities of α linolenic acid, eicosapentaenoic and docosapentaenoic acid. The latter have been shown to reduce the incidence of cardio-vascular disease in humans. While feeding whole linseed has been shown to enhance the fatty acid composition of muscle (Scollan et al 2001), whole linseed is subject to significant levels of biohydrogenation in the rumen. Extruded linseed (Valomega) is promoted as increasing conjugated linoleic acid and α linolenic acid in meat through improving the efficiency of fatty acid metabolism in the rumen and intestine. The objective of the current study was to evaluate the effect of level of inclusion of extruded linseed in diets of dairy bulls on fatty acid composition of meat and instrumental meat quality.