Effect of nitrate administration on rumen fluid and blood composition of sheep
1988
Yoon, C. | Park, J.M. | Chun, W.B. (Chonnam National Univ., Kwangju (Korea R.). College of Agriculture)
An experiment was conducted to investigate the influence of the level of nitrate on the nitrate metabolism including methemoglobin formation in blood. 12 corriedale wethers fed on concentrates and Italian ryegrass hay were administered intraruminally three different levels of sodium nitrate (0.34g, 0.45g and 0.56g per kg of body weight) as 30% (w/v) aqueous solution via rumen fistula. Rumen fluid and blood samples were taken at 1, 2 or 3hrs intervals, and time courses of ruminal pH and nitrite concentration in the rumen, and PVC, hemoglobin and methemoglobin content in blood were determined. The concentration of nitrite in rumen fluid after administration of sodium nitrate into the rumen was highest in the 0.56g sodium nitrate lot, in which the highest methemoglobin formation was found. No appreciable difference was observed in the changing pattern of ruminal pH by the different levels of sodium nitrate application. The concentration of hemoglobin and PVC in blood were increased when the test animals were ingested 0.5g sodium nitrate per kg of body weight. Sodium nitrate (0.34g, 0.45g and 0.56g per kg of body weight) administered in the rumen resulted in a methemoglobin formation corresponding to 19.2%, 22.0% and 47.0% conversion of the total hemoglobin. The individual difference in the capacity of methemoglobin formation and NO ** (-2) concentration in blood plasma after administration of sodium nitrate seemed to be mainly due to the individual difference in the concentration of nitrite in the rumen fluid. Three wethers died, and their maximum methemoglobin values recorded were 67.0%, 80.8% and 87.8% respectively
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