Why traditional bran mashes are falling out of favor in horses: full analysis

A new The Horse commentary is pushing back on one of the most persistent traditions in equine feeding: the weekly wheat bran mash. Clair Thunes, PhD, an equine nutritionist and consultant, writes that the practice may do the opposite of what many barns intend, because a novel bran meal can disrupt the gastrointestinal tract rather than gently support it. She also points to wheat bran’s high phosphorus and low calcium content as a longstanding nutritional drawback. (thehorse.com)

The practice has deep roots in horse management, especially in winter, after hard work, or when a horse seems off feed. Bran mash has long been treated as a comfort feed, a way to “warm” horses up, encourage manure passage, or coax appetite. But modern equine nutrition guidance has steadily moved away from that advice. Merck Veterinary Manual now explicitly says wheat bran is not laxative and recommends avoiding periodic bran mashes because irregular supplementation can cause digestive upset that may be mistaken for a beneficial effect. (merckvetmanual.com)

In her article, Thunes says the main issue is consistency. Horse diets are usually managed carefully to avoid abrupt feed changes, yet the once-weekly bran mash breaks that rule. She writes that any apparent “laxative effect” may actually reflect digestive disturbance. The second issue is mineral balance: wheat bran contains roughly 1% phosphorus and about 0.15% calcium, creating an inverted calcium-to-phosphorus ratio. In horses fed poorly balanced rations over time, that imbalance has historically been associated with nutritional secondary hyperparathyroidism, sometimes called “bran disease” or “big head,” though Thunes notes an occasional mash alone is unlikely to cause that outcome. (thehorse.com)

The broader literature and professional guidance are largely in step with that view. Merck advises that if bran is included at all, it should be a small, regular part of a balanced daily ration, supported by added calcium from sources such as legume forage, beet pulp, or a ration balancer. University of Minnesota Extension likewise cautions against adding ingredients such as wheat bran to a commercial grain mix without understanding how the mineral profile changes. (merckvetmanual.com)

Industry commentary adds nuance rather than much disagreement. Horse & Hound reported that veterinary and nutrition experts still see bran mash used as a traditional tool, particularly when trying to tempt a horse to eat or increase water intake, but they also emphasize caution around mineral balance and sudden dietary change. Kentucky Equine Research has similarly noted that bran mash may still be used in select situations, such as convalescence or for older horses, while rejecting older claims that it meaningfully warms horses in cold weather. (horseandhound.co.uk)

Why it matters: For equine veterinarians, technicians, and nutrition consultants, this is less about one ingredient than about client communication. Bran mash is a good example of a well-intentioned barn practice that survives because it feels gentle and familiar. The practical message for veterinary teams is to redirect the goal, not just reject the tradition: if the aim is hydration, palatability, electrolyte delivery, or a warm meal for a horse that’s gone off feed, those needs can often be met with soaked complete feeds, hay pellets, beet pulp, or other balanced mash products instead of a novel wheat-bran-heavy meal. That framing is more likely to resonate with horse-owning clients and pet parents than simply calling the practice outdated. (thehorse.com)

There’s also a preventive medicine angle. Conversations about bran mash open the door to broader counseling on ration consistency, forage-first feeding, mineral balance, and when to involve a qualified equine nutritionist. For practices managing performance horses, seniors, or horses recovering from illness, those discussions can help reduce avoidable GI upset and improve adherence to feeding plans that are safer over the long term. (merckvetmanual.com)

What to watch: The next step is likely not regulation or a formal guideline change, but continued replacement of traditional bran mashes with formulated mash products and individualized feeding strategies, especially as more veterinarians, nutritionists, and feed manufacturers align around hydration-focused, mineral-balanced alternatives. (thehorse.com)