Document anglais sur la productivité des vaches de boucherie. Which type and size of cattle are most efficient; large ones or small ones? Perhaps fast growing ones are. Or is it slow growing ones? Though currently a hot topic in the cattle industry, the efficiency question is not new and has in fact been debated by cattlemen since the early days of the business. While efficient cattle production has been researched for over a century, it remains remarkably widely misunderstood. This misunderstanding can be costly for the industry as well as individual cattle operations, because important and expensive management decisions are erroneously made based on misinformation or lack of understanding. However, a more productive way to frame the efficiency question is “which cattle are most efficient in a specific environment and production system?” In nature, different breeds of the same species can appear markedly different because they have adapted differently to best fit their specific environment. Similarly, different cattle are efficient in different environments and production systems. Gaining a better understanding of the puzzle pieces of efficiency is critical for cattlemen to maximize profit in their specific operations.