Effects of an intravenous replenishment of salivary components on feed intake in large-bodied goats fed on crushed alfalfa [Medicago sativa] hay cubes

The present research investigated whether or not a feeding-induced hypovolemia (decrease in plasma volume) actually depresses feed intake in large-bodied goats fed on crushed alfalfa hay cubes. The present experiment consisted of three treatments. In the control treatment (NI), a solution was not replenished intravenously. In the ASI treatment, an i.v. infusion of artificial saliva was initiated 1 h before feeding and continued throughout the 2 h feeding period in order to replenish water and NaHCO3 lost from the blood in the form of saliva during the initial stages of feeding. In the MI treatment, mannitol solution with the same osmolality of artificial saliva was infused to replenish only the water lost from the blood in the form of saliva. In the NI treatment, a decrease in plasma volume, estimated by increases in hematocrit and plasma total protein concentrations, was apparent within 15 min of the commencement of feeding. In comparison to the NI treatment, the level of increase in hematocrit and plasma total protein concentrations was decreased by the ASI and MI treatments. In comparison with the NI control, the ASI and MI treatments decreased water intake by 26.1 and 29.3% respectively in large-bodied goats fed on alfalfa hay cubes. The cumulative feed intake in the ASI and the MI treatments for the 2 h feeding period were 44.7% and 31.2% higher respectively than the NI control. The results indicate that the remarkably small amount of feed consumed during the initial stages of the feeding period in large-bodied goats fed crushed alfalfa hay cubes was partly due to a dry forage feeding-induced hypovolemia.