You know how it works. You’ve got heartburn caused by acid in your stomach, so to fix the problem, you eat something that will neutralize the acid. So what if there was a food that livestock could eat that would offset the effects of grazing endophyte-infected tall fescue? Scientists have been looking at chemicals in plants, and they’ve discovered that some of them can help animals so they can graze more endophyte-infected tall fescue.
This new information comes to us from researcher Tiffany Jensen out of Utah State University as part of her doctoral research. She knew endophyte-infected tall fescue contains alkaloids, which are steroidal or protein-like. Tannins and saponins tend to bind with proteins and lipids in the gastrointestinal tract of animals, causing them to be excreted from the body. So it made sense to Jensen that these same toxins might bind with the protein-like parts of the alkaloids in the fescue. If that were the case, the alkaloids would be excreted so that animals would be able to eat more fescue without suffering negative effects.
Researchers also know that different toxins spend different amounts of time in the gastrointestinal tract. Some move through quickly, and others more slowly That means that not only would Jensen have to ask the animals IF the tannin and saponin foods helped, but she’d also have to test for the best order for animals to eat the foods.
Researchers Head to the Pasture
In the summer of 2007, Tiffany Jensen, working with Dr. Fred Provenza at Utah State University, asked animals in pasture what they thought of grazing birdsfoot trefoil (a forage with tannins), alfalfa (a forage with saponins) and endophyte-infected tall fescue and in what order it worked best for them. For her project she planted pastures of each of the forages, so that she would be able to give foodHere’s what she learned:
• When cattle grazed fescue first and then trefoil and alfalfa, they spent less time actively grazing tall fescue.
• If cattle ate trefoil and alfalfa first, the same group of cattle spent from 15 to 50% more time grazing fescue.
• The amount of time spent grazing trefoil and alfalfa was the same whether cattle ate fescue first or second. What this tells us is that animals can eat more endophyte-infected tall fescue if they already have tannins and saponins in their rumens.
In 2008, Jensen returned to her pastures with her cattle to find out more about how the two different legumes affected cattle’s willingness to graze endophyte-infected tall fescue. In one study the animals ate combinations of birdsfoot trefoil and tall fescue. In another, they ate combinations of alfalfa and tall fescue. Here’s what she learned from these tests:
• When cattle ate tall fescue first followed by birdsfoot trefoil the time they spent grazing tall fescue rose and fell from day to day. This is a pattern that researchers have found when an animal is offered a food high in both nutrients and toxinsIt wants the nutrients, so it may eat a great deal, then suffer the effects from the toxins, and subsequently eat much less the next day. When they were allowed to eat birdsfoot trefoil first, they ate more tall fescue and without the swings in the amount eaten.
• Cattle grazing alfalfa first spent 58% of their time grazing tall fescue. But when they ate tall fescue first followed by alfalfa, they spent only 28% of their time grazing it. In fact, they would even lay down and refuse to graze (as shown in the photo to the right), but would start grazing again when they were turned into the alfalfa pastures later in the morning.
• Cattle grazing alfalfa in combination with tall fescue ate more tall fescue regardless of whether they got alfalfa first or second.
Jensen also conducted a pen trial with cattle to see if adding tannins to their water would affect how much freshly cut, endophyte-infected tall fescue they would eat. She found that water with tannins limited both water and forage intake, so this solution is not likely to work for producers in pasture.
What About Sheep?
Jensen’s pen trials with sheep showed that their intake of endophyte-infected forages increased when they were given foods with tannins and saponins, but their intake was not as dramatically influenced by whether they ate the tannins and saponins first or second.
What Can We Do With This Information?
Jensen’s work shows that if your pastures are dominated by endophyte-infected tall fescue, you can increase your livestock’s productivity by adding legumes like alfalfa or birdsfoot trefoil to them. It seems like a fairly simple and cost-effective way to overcome a problem that has caused serious harm to many producers and their herds.
Dr. Jensen’s thesis and dissertation are available on line if you’d like to read them in full:
Lyman, Tiffanny. 2008. Livestock Foraging Behavior in Response to Interactions among Alkaloids, Tannins, and Saponins. Thesis Utah State University All Graduate Theses and Dissertations. Paper 79.http://digitalcommons.usu.edu/etd/79
Jensen, Tiffanny L. 2012. Livestock Foraging Behavior In Response To Sequence and Interactions Among Alkaloids, Tannins, and Saponins. Dissertation Utah State University All Graduate Theses and Dissertations. Paper 1217.http://digitalcommons.usu.edu/etd/1217
