Further along the digestive tract, just past the small intestine, lies the hindgut, composed of the cecum and colon. Within these structures resides a population of microbes that aids in the fermentation of forages. Microbes work best when their environment, including the pH, remains fairly constant.
Though pH can rise and fall due to the quality and quantity of feed in the hindgut, explained Whitehouse, the primary reason for a precipitous drop in pH involves the overfeeding of concentrates. “When too much feed is given in a meal, the sheer bulk overwhelms the foregut (stomach and small intestine) and passes hurriedly and only partially digested to the hindgut,” she said.
“Problem is, the hindgut is not equipped to efficiently digest the primary energy sources in feed; its specialty is fibre processing. As fermentation of grain occurs, the microbial population changes when certain microorganisms die off and others thrive. These changes cause the pH of the hindgut to drop.”
Whereas a normal hindgut pH may be in the 6.5-7 range, an acidic hindgut might be as low as 5, which can bring about acidosis. Hindgut acidosis can be problematic on many levels, as horses with this condition tend to have subclinical symptoms, such as a take-it-or-leave attitude toward feed, weight loss, recurrent mild colic, unusually soft manure, or behavioural changes.
Though researchers are not completely united on the best way to measure pH of the hindgut, faecal pH is a suitable representation of what is going on in the hindgut. Commercial pH kits designed for horses are available, but consultation with a veterinarian and nutritionist are best bets.
If consultation and clinical signs point to acidosis, a hindgut buffer can be fed. EquiShure, a product developed by Kentucky Equine Research, is a time-released buffer that moderates the pH of the hindgut, making it more hospitable for beneficial microbes. EQ
YOU MIGHT ALSO LIKE TO READ THE FOLLOWING BY KENTUCKY EQUINE RESEARCH:
Equine Digestive Health: Omeprazole and the Microbiome – Equestrian Life, April 2021
New EO-3 Passes the Taste Test – Equestrian Life, February 2021