Protein Evaluation of Feedstuffs for Horses.
Authors: Bockisch Franziska, Taubert Johannes, Coenen Manfred, Vervuert Ingrid
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Protein Evaluation of Feedstuffs for Horses The German Society of Nutrition Physiology has recently introduced a new protein evaluation system for equine feeds designed to predict pre-cecally digestible crude protein and amino acids from feed chemistry—a significant step towards more precise nutritional formulation for horses. Researchers chemically analysed 71 commercial feedstuffs and validated the system through a feeding trial in which eight horses received four iso-nitrogenous diets varying in lysine source: a low-lysine control, the control supplemented with synthetic amino acids, the control supplemented with soybean meal, and lucerne pellets, with postprandial plasma lysine kinetics measured to assess bioavailability. The new system correlated well with crude protein content, neutral detergent soluble crude protein, and fibre composition across the feed panel (all p < 0.001), yet the feeding trial revealed important functional differences: soybean meal and synthetic amino acid supplementation produced significantly different plasma lysine responses compared to the control, with synthetic amino acids yielding superior absorption kinetics. Notably, the system appears to underestimate lysine availability from forage-based sources such as lucerne pellets, suggesting that plant-based proteins may behave differently in vivo than the model predicts. For practitioners, this highlights both the utility of the new system for standardised feed comparison and the need for ongoing refinement, particularly regarding forage contributions and individual feed matrix effects on amino acid bioavailability—information that could refine supplementation strategies, especially for performance horses requiring precise amino acid balance.
Read the full abstract on PubMed
Practical Takeaways
- •Feed sources differ substantially in amino acid bioavailability to horses—synthetic amino acids and soybean meal deliver lysine more effectively than lucerne pellets at equivalent dietary concentrations
- •The new protein evaluation system based on chemical analysis (crude protein, NDSCP, NDF) provides a practical tool for comparing commercial feeds, but should be interpreted cautiously for forage-based diets
- •Consider chewing patterns, hindgut microbiota activity, and forage type when selecting protein sources, as laboratory predictions may not fully capture in vivo amino acid availability
Key Findings
- •A new German protein evaluation system estimates pre-cecally digestible crude protein (pcdCP) and amino acids from chemical properties in horse feeds
- •Post-prandial plasma lysine concentrations differed significantly by feed source: CTRL < soybean meal diet (p < 0.01) < synthetic amino acid diet (p < 0.05) when lysine intake was increased from 1.02 to 3.02 g/100 kg BW
- •Estimated pcdCP correlated strongly with crude protein content, neutral detergent soluble CP, and ash-free neutral detergent fiber across 71 feed samples (p < 0.001)
- •Lucerne pellets showed apparent lysine bioavailability that may be underestimated by the new protein evaluation system, suggesting the model requires refinement for forage sources