Cause of bloating
The high nutrition value of legumes such as white clover and alfalfa means they are used extensively in the dairy and red meat industries. But these legumes can cause bloat, a problem that costs up to $150 million a year in Canada.
Bloat is caused by production of a stable foam in the rumen during the initial rapid fermentation of proteins in fresh legume forage. Legumes with condensed tannins do not cause bloat. That’s because the tannins protect protein from microbial breakdown in the rumen. Native pasture is normally a rich source of condensed tannins.
Read Also
VIDEO: Green Lightning and Nytro Ag win sustainability innovation award
Nytro Ag Corp and Green Lightning recieved an innovation award at Ag in Motion 2025 for the Green Lightning Nitrogen Machine, which converts atmospheric nitrogen into a plant-usable form.
White clover and alfalfa are high in protein but don’t have condensed tannins. There is considerable interest in developing, through cross-species genetic manipulation, alfalfa and white clover cultivars with condensed tannins.
The genes needed to create non-bloating alfalfa and white clover might come from tropical plants. Condensed tannins are more common in forage plants originating from warmer regions and are widespread in tropical trees, shrubs and herbaceous plants.
Tannin-containing tropical forages are under study in many parts of the world, but not because they prevent bloat. The same property that protects against bloat in temperate regions causes nutritional deficiencies in livestock grazing in the tropics.
Dry grasses used as feed in the tropics may contain only three to five percent crude protein compared to 15 to 30 percent in temperate forages. In other words, condensed tannins rob the animal of some protein that forage provides.
Tannins will be discussed at the International Grassland Congress in Winnipeg June 8-12 and Saskatoon June 15-19. Held once every four years, the congress is the largest gathering of scientists and researchers involved in the study of grassland issues.
To date, 24 titles under the theme Tannins: Plant Breeding and Animal Effects have been submitted to the congress. They represent research from around the world For more information on the congress call 403-244-2340.
– International Grassland Congress ’97
