With the rise of mineral cost over the past several months, I am concerned about either the use of no minerals or using the wrong mineral as a way to cut cost. There are several nutritional disorders like grass tetney and milk fever that can be traced to an insufficient or wrong mineral program. I am concerned this practice could lead to increases in milk fever (hypocalcaemia) cases in Alabama beef cattle. While most producers focus their attention on grass tetney during the spring, we should not ignore milk fever as another nutritional disorder in beef cattle during this time of the year.
What milk fever is, how to prevent it, its common signs and whether you can treat the disorder are all common questions that need to be addressed. While milk fever is most common in dairy cattle, beef cattle can also be affected. Milk fever is a condition caused by low blood calcium and is characterized by general muscular weakness, circulatory collapse, terminal coma and death. The condition usually occurs in cows at calving or within three to four days post calving in high-producing cows. Cold, wet conditions only elevate the incidence of milk fever. The frequency also increases as the cow gets older and if the cow is fed heavy amounts of grain before calving.
Signs of the disease are common and can be often confused with grass tetney. The cows will be excited, have stiff legs and a staggery gait. It will become drowsy and unable to rise. An affected animal will turn her head into her flank and will have a dry muzzle. Untreated, the cow will go into lateral recumbancy, become bloated and often dies.
Treatment for this disorder must be prompt. Calcium injection applied slowly either intravenously or subcutaneously should correct the problem, but not the cause. Be aware that rapid intravenous injection may lead to cardiac arrest, so a combination of intravenous and subcutaneous injections is useful. Also, realize under dosing is often the cause for a relapse. Cattle will respond rapidly and will get back on their feet rather quickly with this treatment. A producer needs to make sure an adequate dosage is provided according to the directions on the product.
The best way to prevent a case of milk fever is to understand the causes and prevent the problem from occurring. As mentioned earlier, milk fever is caused by low blood calcium. Calcium rich milk is needed for the development of bone in the young calf along with other functions like muscle contraction and transmission of nerve signals. When milk production increases the cow’s calcium demand, her body must be prepared to supply the extra calcium. This calcium must come from her diet and from a process pulling some of the calcium from her bones. Milk fever will develop from her inability to pull the calcium from her bones.
Milk fever can occur in one of the following situations:
Phosphorous within a poorly-balanced mineral program can lead to a mineral imbalance in your cowherd. Phosphorous is a common mineral that will bind to calcium making it unavailable to the cow for utilization. Therefore, a diet with a higher percentage of phosphorous over calcium could lead to milk fever because the cow cannot use the calcium in the diet.
How do you correct this situation? You must first run nutrient analysis on your forage, feed ingredients and soils. Then adjust your mineral program based on this information to prevent disorders. Pay very close attention to your forage and soil information if you use chicken litter as fertilizer. Over 90 percent of the reported cases have occurred in fields fertilized with litter or cattle consuming hay fertilized with chicken litter. Chicken litter has a high percentage of both calcium and phosphorous which could lead to an imbalance.
Calcium levels - A second cause is from either depressed or excess calcium levels in the diet. I do not believe you will have a problem with depressed calcium levels unless it’s from being tied up by phosphorous. Most commercial minerals will provide a high percentage of calcium in their product for cow utilization therefore making low calcium levels in the diet very rare. Excess calcium in the diet can be a major problem and is usually the number one cause for milk fever in beef cattle. This is especially a concern this year due to the use of higher calcium, lower cost minerals. Excess dietary calcium can cause the cow to use dietary calcium less efficiently. Therefore, when the demand for calcium increases at calving, the cow’s body is not prepared to start the process of supplying the additional calcium. This will lead to low blood calcium levels and milk fever. The cause of excess calcium is usually found in a nutrition program utilizing several products high in calcium. The use of chicken litter as a fertilizer source seems to be a common thread in excess calcium levels being found in cattle. This along with a complete mineral that is over 16 percent calcium and/or in combination with cattle being fed a product like soyhulls, also high in calcium, can lead to excess calcium in the diet of cattle.
If you have cows exposed to two of the three situations listed above, you should be very aware of the possibility of milk fever occurring as they prepare to calf.
Prevention is always the easiest to incorporate into your program. Be aware of the calcium and phosphorous levels of your total feeding program, including soil composition. Regulate the amount and the number of times you utilize chicken litter as a fertilizer source. Provide cattle with a complete mineral and vitamin supplement in the proper ratios that meets all of the needs of the animal. Know the mineral composition of any feed ingredients provided to your cattle. While milk fever is not a disorder beef producers are familiar with, it is increasing in frequency and can cost you a lot of money in cattle losses.
Jimmy Hughes is AFC’s animal nutritionist.