Abstract
High roughage diet (HRD) and high concentrate diet (HCD) were given to sheep to study their effects on the secretion rate of parotid saliva and on the sodium, potassium and phosphorus levels of parotid saliva and of blood. Parotid secretion rate was higher in HRD feeding than in HCD feeding, except in the early period of eating. The start of eating caused an abrupt increase in parotid secretion. Secretion rate was lower in 2-hour post-eating period than in the 2-hour pre-eating period in both types of feeding. The sodium level of parotid saliva was higher in HCD feeding than in HRD feeding, except in the early period of eating, though the daily intake of sodium was nearly the same in both types of feeding. Plasma sodium level was little influenced by the types of the diet, except in the post-eating period. The potassium level of parotid saliva was little influenced by the type of diet in the pre-eating period. It was higher in HRD feeding than in HCD feeding in the eating period. Plasma potassium level was influenced neither by the type of diet nor by eating. In response to the daily intake of phosphorus and the parotid secretion rate, the inorganic phosphorus level of parotid saliva and that of plasma were always higher in HCD feeding than in HRD feeding. The hay to concentrate ratio affected the parotid secretion rate and its sodium and phosphorus levels, but not always influenced potassium level of parotid saliva.
