This spring beef producers will be faced with the annual problem of either Milk Fever or Grass Tetany. These problems can typically be handled with some proper mineral supplementation.

Grass Tetany is typically a disorder associated with inadequate levels of magnesium in the blood. It commonly occurs in lactating animals consuming lush green forages with magnesium levels less that .2% and potassium levels greater than 3% and crude protein greater than 25%. If calcium is low in the forage and the pasture has been fertilized, this may contribute to the problem as well. This scenario typically occurs in the first 2-3 weeks of the grazing season. Small grain pastures (wheat/oats/barley/rye) can also be potential problems. Factors such as temperature changes, prolonged cloudy weather, energy intake, and stress can add to the problem.

The following formula should help determine if the forage is prone to cause Grass Tetany:

% Potassium / (% Calcium + % Magnesium)

If the number is greater than 2.2 then the forage is prone to cause Grass Tetany.

Example of actual Barley Hay sample:

Calcium = .48%

Magnesium = .19%

Potassium = 2.67%

2.67/(.48 + .19) = 3.99 This Forage Will Probably Cause Grass Tetany

The initial signs of a magnesium deficiency include nervousness, decreased milk yield, and attentive ears, staggering, twitching skin. Older cows and high milk production cows are more susceptible because they may have decreased body stores of magnesium.

Treatment can be very successful if given early (within 8-12 hours of symptoms) and with limited handling of the animals. Immediate treatment of 200 cc of magnesium sulfate (Epsom Salts) injected under the skin places high levels of magnesium in the system within 15 minutes. Make sure you don not give more than 50 cc in one injection site. Oral magnesium is not as effective because of the time it takes to get into the system. Additionally, cattle should consume 30 g of magnesium daily for 1-2 weeks after treatment.

Prevention mechanisms consist of starting a high magnesium mineral about 30 days prior to pasture turnout. The beef animal needs 20-30 grams/day of magnesium to avoid this problem. The forage will provide some; therefore the mineral needs to provide about 10-25 grams of supplemental magnesium/day. The ProPhos or BosBuilder Hi-Mag minerals if consumed at 4 oz/day will provide about 15 g of magnesium/day.  A caution should be stated with high mag minerals, there might be a palatability problem with these products so consumption needs to be monitored.  We have added highly palatable ingredients to these Land O'Lakes Farmland minerals to alleviate this problem.

Milk Fever is a metabolic disorder that is caused by low blood calcium levels. Initiation of lactation puts a severe strain on the cows due to the calcium levels in milk. Symptoms commonly occur within 3-5 days of calving. The first signs are loss of appetite, constipation, and depression. Nervousness and collapse follow this, and finally unconsciousness with the head usually turned back towards the flank.

The standard treatment is an IV infusion of calcium borogluconate as soon as signs appear. Follow veterinarian recommendations, because and overdose on calcium salts may cause heart damage. Down cows will usually stand within 1-2 hours of treatment.

Prevention of Milk Fever deals with providing the correct amount of calcium prior to calving. Typically what happens is, a producer feeds excess calcium prior to calving, which causes the body to decrease its absorption process. Then when calving occurs and the high calcium demand kicks in, the animal can’t absorb enough and she gets Milk Fever. Therefore the key is to limit the amount of calcium during the entire dry period or feed only 15-20 g/day of calcium 2 weeks prior to calving. This creates a mild calcium deficiency, which in turn stimulates the production of vitamin D, which aids in calcium absorption. Also, maintain at least a 2:1 calcium:phosphorous ratio in the diet, this will help maintain adequate calcium absorption. They main problem occurs when high calcium legumes (alfalfa and clover) are fed in rather high amounts prior to calving. So a key would be to limit alfalfa intake to about 8-10 lbs. 2-3 weeks prior to calving.

Your Land O'Lakes Farmland Cooperative System is here to help you with your spring mineral needs.  Please contact your local cooperative and ask your Livestock Specialist or Beef Specialist for mineral management tips specific to your operation.