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Every nutritionist has a moment when a familiar assumption suddenly looks different. For me, that moment came not in a dairy barn, but recently while reviewing beef research that underscored a truth we sometimes underestimate in dairy: excess protein quietly drains energy. And that drain matters more than many realize.
One study from Jennings et al. (2018) caught my attention. Beef cattle fed poorly balanced protein sources saw more than a 5% increase in maintenance energy use, simply to break down and excrete unused nitrogen. Nothing about that extra energy went toward performance. It was all metabolic housekeeping.
