Straight from the horse's mouth: The effect of different feedstuffs on oral pH in horses and ponies

Feedstuffs, especially ensiled forage, may be detrimental to equid oral health by exposing the oral cavity to low pH. This study aimed to identify if salivary pH was altered by 1) a range of different feedstuffs and (2) specifically by feeding haylages with differing nutrient profiles. Two studies were conducted. The first measured oral pH following five feedstuffs, (hay, haylage, unmolassed sugarbeet pulp, unmolassed alfalfa chaff and rolled oats), tested individually over five days. Saliva (≥1 ml) was collected in triplicate, prior to feeding, directly after ingesting 500 g of each feedstuff, then 15 min and 30 min post-prandially. Oral pH was determined (pH meter) within 10 min of collection. In study two, eight ponies, were fed as their total diet, four different haylages over four 15-day periods. Saliva was collected, prior to feeding and immediately after ingesting 500 g of forage on day 1, day 6, and day 12 of each period. Samples were collected and analysed as per study one. All data were analysed by repeated measures ANOVA, and in study two linear regression was used to attempt to predict nutrients that influenced oral pH. All statistics were conducted in Genstat 20 th Ed. Only feeding unmolassed sugarbeet caused a reduction (p<0.001) in oral pH. There were differences in oral pH depending on the type of haylage fed in study two but at all times oral pH post-feeding was the same or greater than basal pH. These studies suggest any feed associated modulation of oral pH in horses may only be short-lived and quickly buffered by saliva. However, these studies only reflect oral pH within the oral cavity around the feeding occasion and may not reflect gingival pH or the effects of different feeds over longer time periods.