During chewing, feed is mixed with saliva, which is secreted in copious amounts (Table 4). Horses may secrete 40-90 ml saliva per minute, ponies comparatively less (20-60 ml). The jaw movements, and the taste and the smell of feed stimulate salivary secretion. The structure of the feed will affect the amounts of saliva which are produced. Both the chewing time and salivary secretion are much greater when roughages are fed because of their much higher fibre content (Table 4).
Salivary secretion whilst chewing different feeds:
|Feed type||Saliva production|
|Hay and straw||3 - 4|
The saliva of horses does not contain digestive enzymes, but provides minerals and a buffer (sodium bicarbonate) which neutralises acids produced during the fermentation of carbohydrates which may occur in the upper part of the stomach.
Saliva is required for lubricating food before it is swallowed. When eating, balls of saliva and food of between 30 and 70 grams form, these are swallowed about every 30 seconds. The dry matter content of these balls varies with the type of feed and the chewing time. Typical values for concentrates are 40-50% and for roughage 20-30% (Meyer 1986).