The sick Red Angus calf says it all. It's been a rough spring for cattle -- long, cold, and wet. She ended up in the vet clinic "hot box" last night with an IV.
Bob says this has been the worst spring calving season he's seen in 25 years. He's treated many calves for pneumonia and other conditions. It's been a steady stream of farmers bringing cold calves into the clinic.
A farmer called last night about a cow down, possibly from grass tetany. Spring rains came quickly, so pastures are greening up fast. Bob is seeing more problems with this deadly condition caused by low amounts of magnesium in the blood serum after livestock graze young, succulent, cool season grasses. The recent drought can be playing a part, according to this report from Montana State University. Older animals, cows that have recently given birth, those nursing, high milk producers, and fat animals are more susceptible to grass tetany.
Early symptoms include uncoordinated gait, staggering, nervousness, excitability, and muscle spasms. There is only a four- to eight-hour interval between the onset of symptoms and death.
Montana State gives these tips to decrease the likelihood of grass tetany in your herd:
- Graze animals that are less susceptible to grass tetany on tetany-prone pastures (i.e., steers, heifers, stocker calves, cows with calves older than four months).
- Delay spring grazing until grass is 4 to 6 inches tall.
- Graze pastures that have residual standing dead forage present before grazing pastures without.
- Feed animals roughage for 10 to 14 days at the beginning of the grazing season before turning them out on lush, green pastures.
- Feed legumes, which are higher in Mg than grasses, or graze legume pastures first in the spring.
- Do not fertilize pastures with nitrogen (N) or potassium (K) before spring grazing.
- Check animals grazing lush, succulent pastures periodically throughout the day for symptoms of grass tetany.
- Supplement animals with a legume hay.
- Supplement animals with a mineral or protein-energy supplement, using a form that will ensure that every animal will receive 1 to 2 ounces of magnesium oxide per day, for 30 days before spring grazing and for 30 days after the initiation of spring grazing.
- Supplement animals by treating controlled water sources with soluble Mg salt.
- Cull or develop alternative management strategies for animals that develop grass tetany because they will be prone to develop it in the future.
Call your veterinarian if you see signs of grass tetany. A sterile solution containing Mg and Ca (e.g., 200-500 ml calcium magnesium gluconate) can be given slowly to the animal intravenously. Enemas of 60 grams of magnesium chloride dissolved in 200 ml of water, placed in a collapsible, plastic bottle can be administered.