This study aimed to quantitatively evaluate the acid resistance and slow-release properties of two commercial lipid-coated sodium bicarbonate buffers (buffer I and II) designed for equine hindgut supplementation using validated in vitro models. The ability of buffers to resist reacting with acid was evaluated by measuring the gas produced from the incubation of buffers with an acid. Furthermore, the disappearance of the fat coat and the release of sodium bicarbonate were assessed using an in vitro enzymatic digestion method to simulate small intestine digestibility. The results showed that gas production from buffers I and II followed a linear manner. After 30 minutes of incubation in acid, gas production was approximately 16% of that observed in the uncoated. The lipid coating of buffer II was digested to a significantly greater extent than that of buffer I (P<0.001). This consequently led to a significantly greater release of sodium bicarbonate from buffer II (P<0.001). Accordingly, the final buffering capacity of the digesta was significantly higher in the bottle containing buffer II compared to the bottle containing buffer I (P<0.001). In vivo studies involving animals challenged with hindgut acidosis demonstrate the efficacy of equine buffers in supporting gut health.

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