Feed Intake of Goats During Volatile Fatty Acid Injections into Four Gastric Areas

Previous experiments indicate that changes in rumen fluid concentration of volatile fatty acids may be factors in the control of feed intake of ruminants.The present experiment was designed to test the sensitivity of different areas of the stomachs to volatile fatty acids.Water (control) or 1.0 fatty acid solutions (pit = 6.5) (2 days each) were injected into the dorsal rumen, ventral rumen, ventral reticuhnn, or abomasum of goats during spontaneous meals.Acetate (.75 and .65 moles per day) injected into the dorsal rumen or abomasum decreased feed intake 30 and 20% (P < .01).Propionate (approximately .80mole per day) injected into each of the gastric areas decreased feed intake approximately 34% (P < .05).Similarly, a fatty acid mixture (55% acetate, 30% propionate, and 15% butyrate) injected into each gastric area decreased feed intake 23 to 49% (P < .02).We conclude that the dorsal rumen probably contains receptors for acetate and propionate, but the propionate response may be due, in addition, to receptors in the gastric veins.Injections into the abomasum, in contrast to those in the ruminoreticulum, probably result in unphysiologieal concentration changes although there is a similar decrease in feed intake.