Nutritional management of dairy cows to enhance gut functions

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The objective of the proposed research is to evaluate novel nutritional management approaches to enhance gut functions. I have been working to mitigate sub-acute rumen acidosis (SARA) in dairy cows with the support of my NSERC Discovery Grant. The SARA is a metabolic disorder that negatively affects the health and productivity of ruminants. Feeding high grain diets often causes excess fermentation that results in the accumulation of fermentation acids in the rumen (the first stomach of ruminants), leading to systemic inflammation, feed intake reduction, liver abscesses, lameness, and other metabolic disorders. However, it is noteworthy that some animals maintain high feed intake and milk production even with low rumen pH (i.e., SARA). The variable tolerance observed among animals to this condition is not well understood, and the underlying factors warrant investigation. For the current proposal, I hypothesize that glucagon-like peptide 2 (GLP-2), a hormone released from the distal intestine, plays an important role in enhancing gut functions and mitigates the negative consequences of SARA. Because rumen acidosis and excess hind-gut fermentation often increases the entry of lipopolysaccharide, an endotoxin, into blood circulation, enhancing gut barrier function is considered very important to minimize the negative consequences of excess fermentation in the gut. It is well established that GLP-2 plays an important role in gut development and sound gut function, but it is not known how it is involved in minimizing problems related to SARA. I plan to use an acidosis challenge model, where 5 kg of ground grain will be fed after a 2-d 50% feed restriction, to determine if negative effects of SARA would be reduced by continuous administration of a GLP-2 analogue. Furthermore, I will evaluate several nutritional management approaches to potentially enhance plasma GLP-2 concentration, such as butyrate supplementation. I hypothesize that enhancing GLP-2 secretion will minimize systemic inflammation indicated by the serum concentration of acute phase proteins. The proposed research will also investigate the role of supplemental zinc on gut integrity and evaluate if it would minimize systemic inflammation caused by SARA. The proposed research is expected to contribute to sustainable dairy production in Canada by minimizing systemic metabolic problems caused by SARA.