Effect of Abomasal Infusion of Saliva on Reticular Motility and Ruminal Liquid Contents of Steers

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Abstract
Two Holstein and two Jersey steers with ruminal and abomasal cannulas were used in a 4 x 4 Latin square experiment to test the effects of abomasal infusion of saliva on reticular contractions and on contents of the reticulorumen. Steers were fed a ration based on sorghum silage (58.3% DM) at 2-h intervals in 12 equal amounts at 1.25 times the maintenance requirement. Saliva was collected from eight esophageally fistulated steers, pooled, and stored frozen at -20 degrees C. Saliva was mixed with McDougall's buffer (0, 33.3, 66.7, or 100% saliva) and infused abomasally at a rate of 1.5 L/h for 3 h. Abomasal infusion of saliva resulted in linear decreases in ruminal liquid and DM contents. Ruminal dilution rate tended to be faster for infused steers as concentration of saliva increased. Frequency of reticular contractions increased linearly as saliva infusion increased. The influence of saliva infusion on duration of reticular contractions was complicated by inverse patterns of response for each separate phase of the reticular contraction. The first phase of the contraction was influenced by saliva infusion in a negative, quadratic manner; the second phase exhibited an opposite response pattern. A quadratic effect was evident for both amplitude and area of contractions, indicating that the contraction strength was decreased at the intermediate salivary infusion. Postruminal passage of saliva may influence ruminal digestive function by regulating reticular motility and digesta passage.