Spring Time Pastures and Grass Tetany

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Let’s not lie, we all get a little excited when spring comes rolling around. Temperatures are rising and our cool season pastures start to rapidly grow. There is something that you need to be thinking about before you turn your cows and calves out on these lush green pastures. When grass starts growing rapidly, they have a high-water content, which dilutes the amount of nutrients that are in them. This makes forages hard for your animals to eat enough dry matter to meet their nutrient requirements. It occurs mostly during the spring, but can occur in the fall and winter months.

The biggest issue with these high moisture, diluted nutrient grass is a condition called grass tetany. This is a metabolic disorder of cattle when they are deficient in magnesium (Mg). Cows that are in early lactation, or cows that are older are more susceptible to get this than first or second time calves. Grass tetany has occurred on orchard grass, perennial ryegrass, timothy, tall fescue, crested wheatgrass, bromegrass, Kentucky bluegrass, annual ryegrass and small grain (wheat, oats, barley, triticale and rye) pastures. It also can occur when animals are fed hay during the winter months that contains low magnesium (good reason to get your hay tested). One of the greatest potentials for grass tetany is when the soil is low in available magnesium and high in potassium and nitrogen. Putting out too much manure or fertilizer can create this mineral imbalance (good reason to do a soil test).

Probably the worst thing about grass tetany is the symptoms. In most cases the first sign you will see is a dead cow. If you do notice symptoms, it will probably be a mild case. You might notice that the cow is nervous, she will stop grazing and be uncomfortable, showing unusually signs of alertness, such as staring and keeping their head and ears erect, staggering, or their skin will twitch. If you notice any signs that could be related to grass tetany, you need to call the vet immediately.

Like anything else, the best way to avoid this problem is by prevention. The best way thing to do is to feed minerals, but not just any minerals, look for a free choice mineral that contains at least 8-12 percent magnesium. Most of the minerals will be labeled on the bag High Mag or High Magnesium. It should be pretty obvious but if you have any doubt just look at the tag. Also avoid using mineral or salt blocks. Livestock need to have free choice loose minerals. They simply cannot get enough trace minerals by licking a block.

Alternative methods of prevention would be to use a Magnesium supplement. This can be added to a protein supplement, grain mix or a liquid supplement. Also, research has also showed that the risk of grass tetany decreases on pastures that contain over 30% legumes or fed hay that is mixed with some legumes.

In conclusion, the take home message I want you to understand is to utilize what sources are available to you, not only to help increase your production but to also better your herd health. Trying to save a few dollars here and there will not help pay for a dead cow because of a management issue. Minerals are a higher cost, but getting those minerals in your herd will greatly improve their performance. Animals eat minerals when they need them, so if they eat the first bag in a day or so don’t worry. Just keep it free choice and when they get the nutrients, they need they will show down and eat as needed. A forage analysis is just $10 dollars a sample (hay as well as fresh grass) and it can tell you exactly what nutrients are available and if you need to supplement with other feed sources. Lastly, soil samples are free from April to December, during the peak season they are only $4. Soil samples can save you costs on fertilizer because you will know if you are putting out too much or not enough. Wheat