Physiological Factors Depressing Feed Intake and Saliva Secretion in Goats Fed on Dry Forage



Sunagawa, K.;Ooshiro, T.;Nakamura, N.;Ishii, Y.;Nagamine, I.;Shinjo, A

  • 투고 : 2005.08.12
  • 심사 : 2006.01.19
  • Published : 2007.01.01


Ruminants eating dry forage secrete large volumes of saliva which results in decreased plasma volume (hypovolemia) and the loss of $NaHCO_3$ from the blood. The present research investigated whether or not hypovolemia and the loss of $NaHCO_3$ from the blood in goats brought about by dry forage feeding actually depresses feed intake and saliva secretion, respectively. The present experiment consisted of three treatments (NI, ASI, MI). In the control treatment (NI), a solution was not infused. In the ASI treatment, i.v. infusion of artificial parotid saliva was initiated 1 h before feeding and continued for the entire 2 h feeding period. In the MI treatment, iso-osmotic mannitol solution was infused. The NI treatment showed that hematocrit and plasma total protein concentration were increased due to decreased circulating plasma volume brought about by feeding. In the ASI treatment, the fluid and $NaHCO_3$ that were lost from the blood because of a feeding-induced acceleration of saliva secretion was replenished with an intravenous infusion of artificial parotid saliva. This replenishment lessened the levels of suppression on both feeding and parotid saliva secretion. When only the lost fluid was replenished with an intravenous infusion of iso-osmotic mannitol solution in the MI treatment, the degree of feeding suppression was lessened but the level of saliva secretion suppression was not affected. These results indicate that the marked suppression of feed intake during the initial stages of dry forage feeding was caused by a feeding-induced hypovolemia while the suppression of saliva secretion was brought about by the loss of $NaHCO_3$ from the blood due to increased saliva secretion during the initial stages of feeding.


Dry Forage Intake;Saliva Secretion;Feeding Induced Hypovolemia;Goats


  1. Sunagawa, K., Y. Nakatsu, Y. Nishikubo, T. Ooshiro, K. Naitou and I. Nagamine. 2002a. Effects of intraruminal saliva flow on feed intake in goats fed on alfalfa hay cubes. Asian-Aust. J. Anim. Sci. 15:1738-1746.
  2. Sunagawa, K., R. S. Weisinger, M. J. McKinley, B. S. Purcell, C. Thomson and P. L. Burns. 2002b. Effect of intracerebroventricular infusion of urocortin on feed and salt intake in parotid fistulated sheep. Anim. Sci. J. 73:35-40.
  3. Stacy, B. D. and A. C. I. Warner. 1966. Balances of water and sodium in the rumen during feeding: osmotic stimulation of sodium absorption in the sheep. Q. J. Exp. Physiol. 51:65-78.
  4. Sunagawa, K., R. S. Weisinger, M. J. McKinley, B. S. Purcell, C. Thomson and P. L. Burns. 2001. The role of angiotensin II in the central regulation of feed intake in sheep. Asian-Aust. J. Anim. Sci. 14:215-221.
  5. Sasaki, Y., S. Watanabe, Y. Satoh and S. Kato. 1975. Effect of intravenous infusion of artificial saliva on changes in acid-base status of sheep during eating. Jpn. J. Zootech Sci. 46:449-453.
  6. Sato, Y. 1975. The relationship between saliva secretion and body fluid balance during feeding. Ph. D. Thesis Tohoku University, Sendai, Japan.
  7. Prasetiyono, B. W. H. E., K. Sunagawa, A. Shinjo and S. Shiroma. 2000. Physiological relationship between thirst level and feed intake in goats fed on alfalfa hay cubes. Asian-Aust. J. Anim. Sci. 13:1536-1541.
  8. Sasaki, Y., S. Watanabe, Y. Satoh, S Kato and T. Tsuda. 1974. Changes in acid-base status of sheep during eating. Jpn. J. Zootech Sci. 45:8-13.
  9. McKinley, M. J., D. A. Denton, S. Hatzikostas and R. S. Weisinger. 1979. Effect of angiotensin II on parotid saliva secretion in conscious sheep. Am. J. Physiol. 237:E56-E60.
  10. Meyer, A. H., W. Langhans and E. Scharrer. 1989. Vasopressin reduces food intake in goats. Q. J. Exp Physiol. Cogn. Med. Sci. 74:465-473.
  11. Kato, Y. 1988. Analysis of chemical components of feed. Shiryo Bunseki Kijun Tyukai, Japanese Feed Association, Tokyo, Japan, pp. 1-16.
  12. Kay, R. N. B. 1960. The rate of flow and composition of various salivary secretions in Sheep and calves. J. Physiol (Lond.). 150:515-537.
  13. Mathai, M., M. D. Evered and M. J. McKinley. 1997. Intracerebroventricular losartan inhibits postprandial drinking in sheep. Am. J. Physiol. 272:R1055-R1059.
  14. Hidari, H. 1981. The relationships between rumen load and diurnal eating pattern of sheep fed on various time of access to feed. Jpn J. Zootech. Sci. 52:219-226.
  15. Kato, S. 1977. Experimental studies with regard to factors controlling feed intake in sheep. Ph.D. Thesis, Tohoku University, Sendai, Japan.
  16. Warner, A. C. and B. D. Stacy. 1977. Influence of ruminal and plasma osmotic pressure on salivary secretion in sheep. Q. J. Exp. Physiol. 57:103-119.
  17. Van Soest, P. J., J. B. Robertson and B. A. Lewis. 1991. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74:358-3597.
  18. Warner, A. C. and B. D. Stacy. 1972. Water, sodium and potassium movements across the rumen wall of sheep. Q. J. Exp. Physiol. 57:103-119.
  19. Sunagawa, K., Y. Nakatsu, Y. Nishikubo, T. Ooshiro, K. Naitou and I. Nagamine. 2003. Effect of parotid saliva secretion on dry forage intake in goats. Asian-Aust. J. Anim. Sci. 16:1118-1125.
  20. Tsuda, T. 1994. Digestion and absorption. In: Animal Physiology, Youkendo, Tokyo, Japan, p. 149.
  21. Denton, D. A. 1956. The effect of $Na^+$ depletion on the $Na^+$: $K^+$ ratio of the parotid saliva of the sheep. J. Physiol. 131:516-525.
  22. Fitzsimons, J. T. 1979. The physiology of thirst and sodium appetite. Cambridge University Press, Cambridge, UK.
  23. Forbes, J. M. and J. P. Barrio. 1992. Abdominal chemo- and mechano-sensitivity in ruminants and its role in the control of food intake. Exp. Physiol. 77:27-50.
  24. Grovum, W. L. 1995. Mechanisms explaining the effects of short chain fatty acids on feed intake in ruminants-osmotic pressure, insulin and glucagons. Ruminant Physiology: Digestion, Metabolism, Growth and Reproduction. Proceedings of the 8th International Symposium on Ruminant Physiology, (Ed. W. V. Engelhardt, S. Leonhard-Marek, G. Breves and D. Giesecke). Ferdinand Enke Verlag, Stuttgart. pp. 137-197.
  25. Campling, R. C. and C. C. Balch. 1961. Factors affecting the voluntary feed intake of the cow. 1. Preliminary observations on the effect, on the voluntary intake of hay, of changes in the amount of the reticulo-ruminal contents. Br. J. Nutr. 15:523-530.
  26. Carter, R. R. and W. L. Grovum. 1990. A review of the physiological significance of hypertonic body fluids on feed intake and ruminal function: salivation, motility and microbes. J. Anim. Sci. 68:2811-2832.
  27. Blair-West, J. R. and A. H. Brook. 1969. Circulatory changes and renin secretion in sheep in response to feeding. J. Physiol. 204:15-30.
  28. Baile, C. A., J. Mayer and C. L. McLaughlin. 1969. Feeding behavior of goats: ruminal distention, ingesta dilution and acetate concentration. Am. J. Physiol. 217:397-402.
  29. Anil, M. H., J. N. Mbanya, H. W. Symonds and J. M. Forbes. 1993. Responses in the voluntary intake of hay or silage by lactating cows to intraruminal infusions of sodium acetate, sodium propionate or rumen distension. Br. J. Nutr. 69:699-712.
  30. AOAC. 1990. Official Methods of Analysis. 15th ed. Assoc. Off. Anal. Chem. Arlington, VA.
  31. Kato, S., Y. Sasaki and T. Tsuda. 1979. Food intake and rumen osmolality in the sheep. Annales de Recherches Veterinaire. 10:229-230.
  32. Bailey, C. B. 1961. Saliva secretion and its relation to feeding in cattle. 3. The rate of secretion of mixed saliva in the cow during eating, with an estimate of the magnitude of the total daily secretion of mixed saliva. Br. J. Nutr. 15:443-451.