Study models more usable protein measures in equine feedstuffs

A new study in the Journal of Equine Veterinary Science adds momentum to a growing rethink of how horse diets are evaluated for protein. The May 2025 paper, led by R.W. Springer and colleagues, modeled equine pre-cecal digestible crude protein from feedstuff crude protein and fiber composition, aiming to better estimate the protein fraction actually available before hindgut fermentation. The project was also presented at the 2025 Equine Science Society Symposium, underscoring that it’s part of an active research conversation, not a one-off finding. (researchgate.net)

That matters because equine protein recommendations still largely trace back to crude protein-based systems. The National Research Council framework remains the reference point used by many nutritionists and veterinarians, and current educational materials still describe requirements in crude protein grams or percentage of diet. But crude protein is fundamentally a nitrogen estimate, not a direct measure of digestible or biologically useful amino acid supply. Researchers and clinicians have increasingly argued that this can oversimplify ration quality, especially when feeds differ substantially in fiber content, forage maturity, or protein binding within plant cell walls. (thehorse.com)

The newer framework centers on protein fractionation. Earlier published work in Animals described how horse feeds can be divided into neutral detergent soluble crude protein, or NDSCP, and neutral detergent insoluble crude protein, or NDICP. NDSCP is treated as the readily available fraction for foregut digestion, while NDICP is associated with cell-wall-bound protein that may be less accessible in the small intestine. That same paper reported estimated pre-cecal digestible crude protein values across 71 feedstuffs and test diets, illustrating how feeds with similar crude protein totals can differ meaningfully in predicted usable protein supply. (mdpi.com)

Springer and colleagues’ 2025 modeling study appears to extend that concept by asking a practical question: can routine feed composition data, especially crude protein and fiber measures, help predict the soluble protein fraction and therefore pre-cecal digestible crude protein? Even without the full article text publicly available in the sources reviewed here, the title, conference listing, and related literature point to the same goal: making protein fractionation more usable in everyday ration formulation, where direct fractionation assays may not always be available. That’s potentially useful for hay testing, commercial feed assessment, and field ration balancing. This is an inference based on the study title, symposium abstract listing, and the authors’ earlier published work. (researchgate.net)

Industry and expert commentary around equine protein has been moving in a similar direction. Coverage from The Horse quoting equine nutrition researchers, including Kristine Urschel, PhD, and Caroline Loos, PhD, emphasizes that crude protein alone does not describe digestibility or amino acid quality, and that small-intestinal availability is a key part of protein value. Extension and practitioner-facing resources also continue to note that feed tags and hay tests can miss important differences in how well a horse can actually use the protein present. (thehorse.com)

Why it matters: For veterinary professionals, this is less about changing a label number and more about improving clinical nutrition decisions. Horses with higher demands, including growing horses, broodmares, performance horses, and some clinical cases, may need rations optimized for digestible protein quality, not just crude protein quantity. A model that estimates soluble protein from routine feed analysis could help practitioners identify when a ration that looks adequate on paper may still underdeliver at the small intestine, or when higher crude protein is simply coming from less available fractions. That could sharpen forage recommendations, support more precise supplementation, and improve communication with pet parents who often equate a higher protein percentage with a better feed. (mdpi.com)

There’s also a systems-level angle. Better matching protein supply to actual pre-cecal digestible needs could reduce overfeeding of protein, which is common in some mature horses and adds cost without necessarily improving outcomes. More precise formulation may also have implications for nitrogen excretion, an issue that has started to draw research attention in horses as well as other species. A recent pilot study cited in the literature suggests protein partitioning may influence fecal nitrogen profiles, pointing to a possible environmental and manure-management dimension over time. (horses.extension.org)

What to watch: The next step is whether these models are validated broadly enough to move from research settings into commercial forage labs, feed company formulation tools, and practitioner ration software. Watch, too, for follow-on work linking predicted soluble protein fractions to clinical outcomes, performance, growth, or manure nitrogen measures, because that’s what would make this more than a useful analytical refinement. (equinescience.org)