Effects of Sodium Bicarbonate, Sodium Chloride, Limestone, and Monensin on Rumen Fermentation, Rumen Fluid Dilution Rate, and Nutrient Utilization in Ruminants

201 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.Four experiments were conducted to determine the ability of mineral salts and monesin to alter the rumen environment and the efficiency of nutrient utilization in ruminants.In the first experiments, a constant intraruminal infusion of 8 liters of water was compared with the same infusions containing either 288 grams sodium bicarbonate, 200 grams solid chloride, or 600 grams solid chloride in a four x four Latin square design using four rumen fistulated Holstein steers. Dry matter intake was 7.7 kilograms for the high concentrate diet (75% grain mix and 25% corn silage) and 9.9 kilograms per day for the high roughage diet (64% alfalfa hay, 18% corn silage and 18% grain mix). During these experiments oral water intake was increased by the infusion of mineral salts which resulted in an increase in total rumen fluid outflow. In the steers fed the high concentrate diets the molar proportion of rumen acetate increased while the molar proportion of rumen propionate decreased with salt infusions reflecting a net decrease in the production of propionate. In contrast the molar proportion of rumen acetate and propionate were not altered by mineral salt infusions in steers fed the high roughage diet although production rates of the volatile fatty acids were increased. Sodium bicarbonate increased ruminal pH thereby potentially improving the rumen environment for cellulose utilization.In the third experiment four rumen fistulated dairy cows were fed ad libitum a high concentrate diet (75% grain mix and 25% corn silage on a dry matter basis) in a 4 x 4 Latin square design. The treatments were sodium bicarbonate, sodium chloride, and limestone added to the total mixed ration at 2.0, 2.0, and 2.4% respectively. Sodium bicarbonate increased milk fat synthesis which was modulated through changes in the rumen environment. The changes included increase in ruminal pH and rumen fluid dilution rate which led to a decrease in the molar proportion of rumen propionate. Sodium chloride also increased rumen fluid rate but was not as effective as sodium bicarbonate in altering the rumen environment and thus had little effect on the synthesis of milk fat. Limestone was totally ineffective in altering ruminal pH, rumen fluid dilution rate, the molar proportion of rumen propionate, and the synthesis of milk fat. However, limestone supplementation improved the digestibility of starch and decreased the overall digestibility of nitrogen.In the final study dairy calves were fed a high concentrate diet (50% grain mix and 50% corn silage) at an ad libitum level of feed intake. A four x four Latin square design with a two x two factorial arrangement of treatments were used to compare the dietary supplementation of sodium bicarbonate and monensin fed singly or in combination. It was hypothesized that monensin feeding would decrease proteolysis and deamination of amino acids in the rumen and lead to increased amounts of peptides and amino acids reaching the lower gastrointestinal tract via increased water flux through the rumen brought about by feeding sodium bicarbonate. Sodium bicarbonate increased water intake, increased rumen fluid dilution rate and decreased both the molar proportion and production rate of propionate in the rumen. Monensin in contrast, did not affect rumen fluid dilution rate but increased the molar proportion and production of propionate in the rumen. Acetate production was also increased with the monensin treatment. The increase in production of volatile fatty acids per kilogram of dry matter consumed upon monensin supplementation is thought to reflect an increase in retention time or digesta in the rumen resulting from a lower feed intake. The combination of sodium bicarbonate and monensin did not appear to improve the efficiency of nitrogen utilization.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD