With springtime getting ready to make its appearance, many farmers are eagerly looking forward to feeding the livestock nice green grass rather than hay. Once the grass greens up, our cows are likewise excited about eating sweet field grasses. However, one problem that farmers must be aware of in the spring is a condition called grass tetany.
Grass tetany, also named winter tetany, lactation tetany, wheat pasture poisoning, and grass staggers, is caused by a deficiency of magnesium in the blood of affected animals. Cattle cannot store much magnesium in their bodies; they generally rely on a steady source of this important mineral from their feed.
The lush, green grasses of spring, while loaded with some important minerals and vitamins, are often deficient in magnesium. Especially if the fields were recently fertilized with nitrogen, the grasses won't supply the cattle with adequate magnesium. If you add in a warm weather period followed by a cool, rainy period, this problem may be magnified.
Fully-grown cows are the most likely animals to end up with grass tetany. Additionally, if a cow is near to giving birth or has given birth in the past 8 to 10 weeks, she is much more likely to have grass tetany. This is because of the demands that late pregnancy and lactation place on her body. Young heifers and steers have been known to get grass tetany, but it is fairly unusual for this to occur.
Symptoms of Grass Tetany
Sometimes, farmers will actually find an animal lying on its side convulsing. However, most of the time, a dead animal is found and that tips them off that they have a problem. The animal will be lying on its side with its head kinked back. The ground may show evidence that the feet were paddling furiously before the animal died. The duration between the first symptoms of grass tetany and the death of the animal can be as short as 4-8 hours. Before the cow goes down, she may be over-excited, froth at the mouth, and exhibit twitching. However, these symptoms are of the acute stage of grass tetany.
In the sub-acute form of grass tetany, the symptoms may be missed. The animal may remain on its feet, but it may walk with an abnormal gait, blink more often than normal and go off-feed. Eventually, the cow will lose weight and her milk supply will suffer. Sub-acute grass tetany may not be as obvious, but it will eventually result in the death of the cow. Some animals can also exhibit chronic grass tetany. They will be unsteady and clumsy, exhibiting twitching, dullness and suppressed appetite.
Grass tetany can strike your herd quite unexpectedly. Grass tetany is one of those problems that is better to prevent than to treat. In part 2 of grass tetany, treatment and prevention of this metabolic problem will be presented.