Using Condensed Tannins to Improve Efficiency of Ruminant Production and Minimize Environmental Impact
Condensed tannins are plant-produced chemicals that demonstrate interesting biological activities in livestock that consume them. Some of these activities include binding to minerals, carbohydrates, proteins and lipids, as well as altered digestion (fermentation). I focus on identifying and understanding the factors that affect CT concentrations, biological activity, and their effects on animal production and the environment. Including CT-producing plants into livestock diets will 1) improve efficiency of nutrient utilization in ruminants (cattle, sheep, goats), leading to improved animal performance and production of animal products; and 2) reduce production and emission of greenhouse gases (carbon dioxide and methane) and other pollutants (ammonia) by ruminants. My overall objective is to use CT to improve the production of ruminant animals and minimize the impact of livestock production on the environment. To accomplish this requires understanding how CT differ across different plant species grown in various environments under different management practices and how these difference subsequently affect livestock production. My three areas of focus are increasing energy intake by reducing methane production, increasing protein utilization which decreases ammonia production, and mitigating intestinal parasite infections.
Condensed tannins and ruminal methane emissions
The production of methane by ruminant livestock represents an inefficiency of animal production. Methane is a waste of carbon that could instead be used as a source of energy to the animal. Methane is also recognized as a potent greenhouse gas. Livestock contribution to greenhouse gas production is estimated to be 14.5% of all anthropogenic greenhouse gas emissions, and in the U.S., represents 23% of emissions from the agriculture sector.
Condensed tannins are naturally occurring chemical compounds produced by many plants and some have the ability to suppressmethane emissions from livestock. I have identified several plant sources of CT that decrease ruminal methane production. I am evaluating relationships among concentration, source and chemical structure of CT related to greenhouse gas production by ruminants. A key output of this work involved the creation of a model to predict ruminal methane inhibition by CT using non-linear exponential decay regression analysis. Our model predicts a reduction in ruminal methane emissions by 50% when including CT at a concentration of 4% of the diet. This work led to an invitation to present at the International Meeting of Advances in Animal Science in Brazil.
I initiated a collaboration among MU, a Forage Chemist at the USDA-ARS Dairy Forage Research Center and a Tannin Biochemist at the University of Miami, Ohio to elucidate the structure-function relationships associated with CT. A recent discovery from this work is that the antioxidant activity of the CT is highly correlated with methane production(J18). However, methane reduction may also be related to changes in rumen microbial population due to the compounds’ selective toxicity towards methane-producing microbes. I am working to determine the dose-response effect of dietary CT on 1) ruminal methane production and overall animal energy use, and 2) changes in rumen-microbial populations associated with methane production.
Condensed tannins and protein utilization
Inefficient protein utilization by ruminants results in urea excretion, which breaks down to volatile ammonia, a precursor to the harmful greenhouse gases known as nitrous oxides. Condensed tannins characteristically bind to proteins. Altering protein digestion with CT will increase protein utilization and meat and milk production by ruminant animals, while decreasing environmental impact. Increasing CT concentration in ruminant diets decreases the extent of ruminal protein degradation and ammonia production.
Condensed tannin-mineral interactions
Condensed tannins bind to minerals, especially iron. Some animals, such as African Black Rhinoceros commonly accumulate iron to the point of toxicity. Increasing dietary CT increases the iron-binding capacity of diets formulated for rhinos and can prevent iron toxicity. This is especially important for captive rhinos (zoo animals).
I have determined that plant mineral nutrition is another factor affecting CT. Specifically calcium, a potential cofactor for enzymes involved in CT biosynthesis, impacts CT production in Illinois bundleflower. My research suggests that availability of Ca impacts the concentration and bioacivity of CT and that Illinois bundleflower responds to calcium deficiency by increasing CT production and protein binding ability.
Condensed tannins and gastrointestinal parasite infections
Intestinal parasite resistance to commercial antiparasite drugs is widespread in sheep and goat production. The use of CT to combat parasites is not well understood. As a member of the American Consortium for Small Ruminant Parasite Control, I have explored the use of CT in ruminant diets to control intestinal parasites. I collaborated with Drs. James Caldwell and Bruce Shanks (Lincoln U.) to explore using CT from wine production for intestinal parasite control in sheep and goats. We researched the use of Pinot Noir and Chambourcin grape extracts as natural dewormers. Pinot Noir was an effective strategy for controlling parasites in lambs.
Using condensed tannins as part of sustainable livestock production systems is a viable means of improving animal nutrition and increasing animal production and efficiency while decreasing contribution of harmful pollutants and greenhouse gases to the atomosphere.