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Controlling Factors of Feed Intake and Salivary Secretion in Goats Fed on Dry Forage

  • Sunagawa, K. (Faculty of Agriculture, University of the Ryukyus) ;
  • Ooshiro, T. (Faculty of Agriculture, University of the Ryukyus) ;
  • Nakamura, N. (Faculty of Agriculture, University of the Ryukyus) ;
  • Nagamine, I. (Faculty of Agriculture, University of the Ryukyus) ;
  • Shiroma, S. (Faculty of Agriculture, University of the Ryukyus) ;
  • Shinjo, A. (Faculty of Agriculture, University of the Ryukyus)
  • Received : 2004.10.07
  • Accepted : 2005.03.25
  • Published : 2005.10.01

Abstract

The purpose of this research was to determine whether or not feeding induced hypovolemia (decreases in plasma volume) and decreases in plasma bicarbonate concentration caused by loss of $NaHCO_3$ from the blood, act to suppress feed intake and saliva secretion volumes during the initial stages of feeding in goats fed on dry forage. The animals were fed twice a day at 10:30 and at 16:00 for 2 h each time. Prior to the morning feeding, the collected saliva (3-5 kg) was infused into the rumen. During the morning 2 h feeding period (10:30 to 12:30), the animals were fed 2-3 kg of roughly crushed alfalfa hay cubes. At 16:00, the animals were fed again with 0.8 kg of alfalfa hay cubes, 200 g of commercial ground concentrate and 20 g of sodium bicarbonate. In order to compensate for water or $NaHCO_3$ lost through saliva during initial stages of feeding, a 3 h intravenous infusion (17-19 ml/min) of artificial mixed saliva (ASI) or mannitol solution (MI) was begun 1 h prior to the morning feeding and continued until the conclusion of the 2 h feeding period. The physiological state of the goats in the present experiment remained unchanged after parotid gland fistulation. Circulating plasma volume decreases caused by feeding (estimated by increases in plasma total protein concentration) were significantly suppressed by the ASI and MI treatments. During the first 1 h of the 2 h feeding period, plasma osmolality in the ASI treatment was the same as the NI (non-infusion control) treatment, while plasma osmolality in the MI treatment was significantly higher. In comparison to the NI treatment, cumulative feed intake levels for the duration of the 2 h feeding period in the ASI and MI treatments increased markedly by 56.6 and 88.3%, respectively. On the other hand, unilateral cumulative parotid saliva secretion volume following the termination of the 2 h feeding period in the ASI treatment was 50.7% higher than that in the NI treatment. MI treatment showed the same level as the NI treatment. The results of the present experiment proved that the humoral factors involved in the suppression of feeding and saliva secretion during the initial stages of feeding in goats fed on dry forage, are feeding induced hypovolemia and decrease in plasma $HCO_3^-$ concentration caused by loss of $NaHCO_3$ from the blood.

Keywords

Hay;Saliva Secretion;Hypovolemia;Plasma Bicarbonate;Goats

Acknowledgement

Supported by : Exploratory Research of the Ministry of Education, Science, Sports and Culture in Japan

References

  1. Guyton, A. C. and J. E. Hall. 1996. Central nervous system centers for thirst. p. 361 in Textbook of Medical Physiology. W.B. Saunders Company, Philadelphia. PA.
  2. Kato, Y. 1988. Analysis of chemical components of feed. Page 1-16. in Shiryo Bunseki Kijun Kyoukai. Tokyo, Japan.
  3. 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.
  4. Sato, Y. 1975. The relationship between saliva secretion and body fluid balance during feeding. Ph. D. Thesis Tohoku University, Sendai, Japan.
  5. Sunagawa, K., R. S. Weisinger, M. J. McKinley, B. S. Purcell, C. Thomson and P. L. Burns. 2001. The effect of water deprivation on cerebrospinal fluid constituents during feeding in sheep. Asian-Aust. J. Anim. Sci. 14:467-473.
  6. Sunagawa, K., Y. Nakatsu, Y. Nishikubo, T. Ooshiro, K. Naitou and I. Nagamine. 2002b. Effects of intraruminal saliva flow on feed intake in goats fed on alfalfa hay cubes. Asian-Aust. J. Anim. Sci. 15:1738-1746.
  7. 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.
  8. 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.
  9. 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.
  10. Tsuda, T. 1994. Digestion and absorption. Page 149 in Animal Physiology. Youkendo, Tokyo, Japan.
  11. 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.
  12. 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.
  13. 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.
  14. Sunagawa, K., R. S. Weisinger, M. J. McKinley, B. S. Purcell, C. Thomson and P. L. Burns. 2002a. Effect of intracerebroventricular infusion of urocortin on feed and salt intake in parotid fistulated sheep. Anim. Sci. J. 73:35-40.