Colour of fat, and colour, fatty acid composition and sensory characteristics of muscle from heifers offered alternative forages to grass silage in a finishing ration.

The effect of type of silage offered to beef heifers during the finishing period on aspects of beef quality was determined. In two experiments, a diet based on grass silage (GS) was compared with a diet based on maize silage (MS) or whole-crop wheat silage (WCW). Compared to the GS-based diet, increasing the amount of MS linearly increased fat whiteness while the increase in fat whiteness due to WCW was dependent on the stage of crop maturity at harvesting. There was no effect of diet on muscle colour or on muscle pH measured at 48h post-mortem, drip loss, taste panel traits after 14days ageing or shear force values at 2, 7 or 14days ageing. The alternative silages decreased the n-3 polyunsaturated fatty acid proportion and increased the linoleic:linolenic acid ratio in intramuscular lipid. It is concluded that type of silage affects fat colour and fatty acid composition of muscle but not the other muscle characteristics examined.