Replacing barley with oats in the supplement to grass silage-fed beef cattle: intake, feed efficiency, carcass traits, and beef colour, fatty acid composition and sensory characteristics

Context Within grass-based beef production systems in temperate climates, cattle are generally housed during winter and offered grass silage ad libitum with sufficient supplementary concentrates to reach commercial target growth rates. The concentrate is generally cereal-based with barley and wheat predominating but there is growing interest in oats due to it’s agronomic suitability and role in tillage production systems. Aims This study compared the effect of replacing barley with oats in a concentrate supplement on feed intake, growth, carcass and selected meat quality traits of beef cattle offered grass silage ad libitum. Methods Twenty-four late-maturing breed steers were assigned to either: (1) barley-based (862 g rolled barley/kg fresh weight) or (2) oats-based (853 g rolled oats/kg fresh weight), supplementary concentrate treatments. Concentrates were prepared as coarse mixtures and formulated to have similar levels of metabolisable protein. Steers were individually offered 4.0 kg dry matter of the respective concentrates daily, as a supplement to Lolium perenne-dominant grass silage (dry matter digestibility, 713 g/kg) for 124 days prior to slaughter. Key results Replacement of barley with oats in the concentrate supplement had no effect on grass silage or total dry matter intake, final live weight, daily live weight gain or feed conversion ratio. Ultrasonographic measurements of rib fat and lumbar muscle gain were greater for barley compared to oats, but there was no difference between the two cereal-based concentrates for lumbar and rump fat gain. Carcass weight, fat and conformation score, subcutaneous fat depth and estimated carcass composition did not differ between the two concentrate types. Replacing barley with oats in the concentrate supplement had no effect on subcutaneous fat colour, or M. longissimus dorsi muscle pH, drip loss, colour or sensory characteristics but increased the polyunsaturated to saturated fatty acid ratio in muscle lipid. Conclusion Rolled oats can replace rolled barley in a concentrate supplement to moderately-high digestibility grass silage without negatively affecting intake and performance or selected meat quality traits of beef cattle. Implications The findings of this study will assist producers when selecting the most attractive supplement composition for grass-silage finished beef cattle.