Pasture season is an opportunity to relax a little due to a lessening of feeding chores, but it is not time to relax about our livestock’s nutrition. For most beef cattle this is a time to replenish their vitamin and mineral stores after a long winter on dry feed. It is also a time when the new production cycle is beginning.
It is also the start of a new production cycle for our grasses — all that lush spring growth just waiting for the livestock to eat it. With spring taking so long to come, accompanied by fast growth of grasses, there is reason to be watchful for grass tetany.
Grass tetany symptoms include depressed appetite, reduced weight gain, nervousness, staggering, stiff gait, convulsions and paralysis, usually in mature cattle. Tetany is caused by low blood magnesium (Mg). Symptoms are similar to milk fever, which is caused by a low blood calcium level and both conditions are often seen in mature cows in late pregnancy (about six weeks before calving) or soon after calving. Either of these conditions can occur anytime during lactation if the circumstances are right.
- More Grainews: Proper mineral supplement can prevent grass tetany
Watch for signs
Often the first sign is a dead animal. It can be difficult to tell whether the cow died from milk fever or tetany. Check around the cow’s body for signs of struggling (marks on the ground) or paddling on the ground around her head and legs. If these signs are present the cow likely died from tetany. Cows affected by the symptoms of grass tetany are often excitable, or “flighty,” appear unco-ordinated, have a stiff gait, tremble, stagger or may be down. Once an animal is down their death is imminent. Producers should contact their veterinarian immediately if their cattle show any of these symptoms.
There are several theories about what triggers this condition. It is thought that high levels of potassium in forages can decrease absorption of magnesium and most lush, immature forages are high in potassium. High levels of nitrogen fertilization have also been shown to increase the incidence of tetany although feeding protein supplements has not. Other factors such as the presence of certain organic acids in tetany-causing forages have been linked with tetany.
Salt is important
Veterinary pathologist Thomas Swerczek found that livestock simply must have access to a good-quality loose salt in order to maintain a proper balance. Without adequate sodium in the blood, the body grabs onto the most available cation, which would be magnesium, followed by calcium. This is characterized by what happens when livestock succumbs to grass tetany after a frost. When the cow consumes frost-damaged forage, particularly alfalfa, and the spike of nitrate occurs, her body accesses magnesium in the blood to eliminate the nitrate. During cool, wet conditions or regrowth after frost or drought, sodium levels in certain forages plummet, while nitrogen and potassium levels spike. It is likely that combinations of factors, all related to characteristics of lush forage are involved. This depletes the body and the cow goes down.
There are other problems that can occur due to a lack of nutritional balance. Grass tetany is an example of a dramatic result. A nutrient imbalance can lead to less obvious conditions such as sporadic calving. And a higher than normal occurrence of illness in young stock due to a lower-than-optimal immune system can also be linked to a poor nutritional balance during pasture season.
What I hear from many producers though is that livestock should only need to have salt licks on pasture for the summer. Cost of minerals is prohibitive. If a beef cow eats four ounces of mineral a day (which ours never do) it would require two 50-pound bags of mineral a year. We buy mineral for approximately $35 a bag and mix it 50 per cent with blue iodized cobalt salt, which is about $10 a bag. So, we’d be running about $80 per year per cow for salt and minerals if this high-consumption rate were maintained.
- From the Canadian Cattlemen: Supplementing Vitamins A, D, and E to beef cattle
On top of this we administer selenium/vitamin E to our babies at birth, as per veterinarian’s instructions, for pennies an animal. The result of spending this money has been a dramatic reduction in sick young stock. The hidden benefit to supplying salt/mineral to pasture animals is that it provides motivation to visit them more often. Many a health problem has been caught early during these visits.
Before we started doing this almost every calf born got pneumonia or scours. After two years of this protocol we now only treat sporadically. This year’s biggest issue was a viral pneumonia. Our veterinarian assured us our best chance of combatting it was through immune system support (vitamin therapy of dam and baby). We are still fighting with sporadic calving, though our sheep and goats have definitely responded with tighter baby seasons. Mineral mixes high in vitamin A can also improve reproduction and reduce cases of pinkeye and ringworm. These conditions have been almost eliminated on our farm since we got aggressive with minerals.
The biggest saving, which is very hard to put a price on, is human stress. There isn’t a farmer out there that doesn’t find treating sick/dying stock very emotionally/physically hard. Add financial strain to that and it is a recipe for a very depressed place to be.
Thomas Swerczek didn’t guarantee that constant supply of high-quality livestock salt would be a magic remedy, but his research does show it is a very good start to maintain good herd health.