Caecal fermentation characteristics of commonly used feed ingredients.
Authors: Ochonski Patricia, Drouillard James S, Douthit Teresa L, Vahl Christopher, Lattimer James M
Journal: Equine veterinary journal
Summary
# Editorial Summary Feed ingredient selection remains a practical concern for horse owners and nutritionists, yet comparative data on how common grains and by-products influence caecal fermentation are limited. Ochonski and colleagues used six cannulated Quarter horses in a Latin square design to measure caecal pH and volatile fatty acid (VFA) concentrations across six feed treatments: beet pulp, maize, dehydrated alfalfa, oats, soybean hulls, and wheat middlings, each fed at 0.25% bodyweight daily alongside bromegrass hay; digesta samples were collected at two-hourly intervals seven days into each treatment period to allow adaptation under realistic management conditions. Surprisingly, no significant differences emerged between treatments for overall pH or VFA concentration (all P ≥ 0.3), though time-of-day effects and ingredient-by-time interactions did occur, confirming the expected post-prandial shifts in caecal metabolism regardless of which ingredient was fed. Caecal pH remained within normal limits across all treatments, suggesting that individual grain or by-product inclusion at modest levels poses minimal risk to hindgut fermentation stability—a reassuring finding for practitioners formulating concentrates. The authors acknowledge that their short adaptation period mimics field practice but note that ingredient interactions within mixed concentrate formulations remain unexplored, indicating scope for further investigation before drawing firm conclusions about more complex feed combinations.
Read the full abstract on PubMed
Practical Takeaways
- •Individual feed ingredients tested here have minimal impact on caecal fermentation parameters when fed separately at moderate inclusion rates, suggesting ingredient choice alone is unlikely to destabilise the caecum in healthy horses
- •Beet pulp pellets may present choking risk in some horses; consider soaking or alternative forms if choke history exists
- •The short 7-day adaptation period reflects real farm conditions but may mask effects of longer-term dietary shifts—monitor horses during feed changes and observe for post-feeding metabolic patterns
Key Findings
- •No significant main effects of feed ingredient type (beet pulp, maize, dehydrated alfalfa, oats, soybean hulls, wheat middlings) on caecal pH or VFA concentration when fed at 0.25% BW/d
- •Caecal pH remained within normal limits across all treatments regardless of ingredient type
- •Significant hour × treatment interactions (P ≤ 0.04) detected for all response variables, indicating post-prandial shifts in caecal metabolites vary by ingredient
- •Three horses exhibited oesophageal choke with beet pulp pellets, highlighting a practical risk with this ingredient form