Ruminants and glucose

Ruminants do not absorb much glucose from the feed. Yet, productive functions and maintenance are highly reliant on glucose supply. During the lactation period, the demand from the milk synthesis process makes glucose a very important substance for ruminants. Ruminants absorb glucose precursors from fermentation and digestion processes: through glucose synthesis in the liver, these precursors are transformed into glucose and consumed in the ruminants’ metabolism process. As the milk yield continues to increase nowadays, dairy cows’ demand for glucose has also increased. A cow that produces 60kg of milk on a daily basis requires over 4kg per day of mammary glucose (Hanigan et al., 1992). Multiple studies have shown that the requirements of the mammary gland during the milk synthesis process dominates the glucose requirements of dairy cows. The metabolism system provides glucose from the glucose synthesis process in the liver. We need to note that the rumen bypass rate of starch is low. Also, only a limited amount of glucose is absorbed in abomasum or duodenum. Intestinal starch absorption also increases starch fermentation in the hindgut. And that is the reason we want to use rumen bypass glucose (RBG) for dairy cattle. In early lactation, rumen bypass glucose increases blood glucose and peak milk yield. An increase in milk yield during lactation helps the cattle to achieve higher peak milk yield. Rumen bypass glucose can also improve cattle health in early lactation. RBG decreases DMI which affects the propionic acid production. RBG also decreases glucose synthesis in the liver which leads to hypoglycemia. Subclinical ketosis can also be prevented.