While cases in some years are more prevalent than others, I expect an increase in milk fever (hypocalcaemia) cases in Alabama beef cattle this year. A conversation with a local veterinarian indicated he also expects increased cases this spring. 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.
Some common questions about milk fever are: What is milk fever? What are its common signs? How do you treat it? Can you prevent the disorder?
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-production cows. Cold, wet conditions elevate the incidence of milk fever. The frequency also increases as the cow gets older and is being fed heavy amounts of grain before calving. While milk fever is most common in dairy cattle, beef cattle can also be affected.
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. The cow will become drowsy and will be unable to rise. An affected animal will turn her head into her flank and 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, either slowly intravenously or subcutaneously, should correct the problem, but not the cause. Be aware rapid intravenous injection may lead to cardiac arrest, so a combination of intravenous and subcutaneous injections is useful. Cattle will respond rapidly and will get back on their feet rather quickly when treated in this manner. Realize that under-dosing is often the cause for a relapse.
The best way not to have 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 increases and her body must be prepared to supply the extra calcium. This calcium must come from her diet and from a process that pulls some of the calcium from her bones. Milk fever will develop from her inability to pull the calcium from her bones.
One cause of milk fever is a poorly balanced mineral program leading to a mineral imbalance. 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 its 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 upon this information.
Pay very close attention to your forage and soil information if using chicken litter as fertilizer. Chicken litter has a high percentage of both calcium and phosphorous which could lead to an imbalance.
I realize a lot of producers utilized chicken litter as fertilizer this past year due to the high cost of commercial fertilizer. A large percentage of reported cases this spring will occur when cows are grazing in fields fertilized with litter or where they were consuming hay fertilized with litter.
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 their diet very rare.
Although it may sound contradictory, excess calcium in the diet can be a major problem and is usually the number one cause for milk fever in beef cattle. Excess 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 from her body. 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 the common thread in excess calcium levels being found in cattle. This along with a complete mineral over 16 percent calcium and or in combination with cattle being fed a product like soyhulls that is also high in calcium can lead to excess calcium. If you have cattle exposed to two of the three situations previously listed, you should be very aware of the possibility of milk fever occurring in cows 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 and that meets all of their nutritional needs. 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 a lot of money in cattle loss.