Super Legumes: The Benefits of Condensed Tannins in Pasture Forage
Whether you’re establishing a new pasture or renovating an existing pasture, incorporating legumes into your grazing system is one of the best decisions you can make. Grass/legume pastures consistently produce higher yields with better nutrient content. For livestock grazing, legumes are important because they offer rich amounts of digestible protein, calcium and minerals. Legumes also help increase soil fertility thanks to their unique nitrogen fixing capabilities. However, not all legumes are created equal. There are some types of legumes that contain chemical compounds known as condensed tannins. These “super legumes” offer even greater benefits for ruminants such as cattle, goats, sheep, llamas, alpacas, deer and other animals.
Eliminates Bloat Risk
Perhaps the biggest limitation when using legumes as pasture forage is bloat risk. Bloat is caused by the formation of foam in the rumen. This foam traps the gases that are produced as a normal result of the fermentation process inside the rumen. The trapped gas, which would normally be belched out by the animal, can lead to discomfort and even death. Bloat is most common in pure legume stands. It’s for this reason that generally only 10-25 percent of a pasture should be composed of legumes with the rest being composed of grass species. On the other hand, legumes that contain condensed tannins don’t cause bloat thanks to their ability to bind to proteins in the rumen. This chemical reaction between proteins and condensed tannins in the rumen halts the formation of bloat-causing foam.
Suppresses Internal Parasites
Legumes containing condensed tannins have also been shown to suppress internal parasites, especially in sheep and goats. This is great news for producers who are starting to see traditional chemical dewormers lose their effectiveness. While the exact mechanism is still being explored, numerous studies have shown that condensed tannins reduce parasite numbers, prevent the adult worms from laying eggs and hinder the development of parasite larvae.
Reduces Agricultural Emissions
Diets high in condensed tannins are also easier on the environment. Studies are just now revealing that when ruminants are grazed on forages high in condensed tannins, the amount of ammonia volatilized from their manure is reduced. Other studies have suggested that condensed tannins also decrease methane emissions. Ammonia and methane contribute to poor air quality, and every effort to reduce these emissions within agriculture should be considered.
Meet the "Super Legumes"
The legumes best known for their condensed tannins are birdsfoot trefoil, sainfoin, and purple prairie clover. Forage chicory also contains high levels of condensed tannins and, while not a legume, still provides the same benefits as the other species when used in a pasture setting. Cicer milkvetch contains a small amount of condensed tannins, but is still considered a bloat-free legume.
Pasture Blends Developed Using the Latest Research
Here at Nature’s Seed, we’ve taken into account the latest research on condensed tannins and put together sheep and goat pasture blends containing these forage materials. When incorporating these “super legumes” into a pasture setting, it’s possible to graze animals on a much higher percentage of legumes than normal. In fact, it’s common to see cattle and other ruminates grazing on pure stands of sainfoin and birdsfoot trefoil with no problem at all.