How Protein Source Affects Protein Metabolism in Ruminants

Jul 01, 2025

By Warren Rusche and Madeliene Nichols

Distillers grains have become the standard supplemental protein source for growing and finishing beef cattle. They are readily available in the Midwest, usually priced attractively, and contain appreciable amounts of crude protein. While it is common to balance beef cattle diets based on the crude protein system, it does not paint an accurate picture of what is occurring inside the animal, leading to gaps in nutrition and economic losses. To overcome these issues, many producers and nutritionists have adopted the metabolizable protein system, which partitions the protein requirements into those of the ruminal microorganisms and the host.

Rumen microorganisms require peptides, amino acids, and ammonia to grow and to break down feed nutrients. These inputs can be supplied by ruminally degradable protein (RDP) from feedstuffs or ammonia from non-protein nitrogen (NPN) can also be used by the rumen microbes. Most cattle diets meet or exceed microbial RDP requirements, but in instances where RDP is low, the rumen microorganisms will recycle urea to meet their requirements.

Source : sdstate.edu

Video: Evolution of Beef Cattle Farming

The Clear Conversations podcast took to the road for a special episode recorded in Nashville during CattleCon, bringing listeners straight into the heart of the cattle industry. Host Tracy Sellers welcomed rancher Steve Wooten of Beatty Canyon Ranch in Colorado for a wide-ranging discussion that blended family history and sustainability, particularly as it relates to the future of beef production.

Sustainability emerged as a central theme of the conversation, a word that Wooten acknowledges can mean very different things depending on who you ask. For him, sustainability starts with the soil. Healthy soil produces healthy grass, which supports efficient cattle capable of producing year after year with minimal external inputs. It’s an approach that equally considers vegetation, animal efficiency, and long-term profitability.

That philosophy aligned naturally with Wooten’s involvement in the U.S. Roundtable for Sustainable Beef, where he served as a representative for the Colorado Cattlemen’s Association. The roundtable brings together the entire beef supply chain—from producers to retailers—along with universities, NGOs, and allied industries. Its goal is not regulation, Wooten emphasized, but collaboration, shared learning, and continuous improvement.