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Identifying nutritional health deficiencies in calving season

Melinda Ellison for Progressive Cattleman Published on 24 January 2019
Watch for grass tetany

As calving season approaches, we all try to make sure our cows have enough good-quality feed to get through gestation and lactation. Often, there are no problems meeting energy and protein requirements, but vitamins and minerals can easily be overlooked.

These are the most difficult to account for because they can be picked up by the animal through soil, water, feed and supplements. However, correct levels of vitamins and minerals are essential for development and performance of cattle, especially for young, growing calves.

To avoid vitamin and mineral deficiencies or toxicities, we can first get an understanding of our local soil, plant and water mineral composition by visiting the local extension office or Natural Resources Conservation Service (NRCS) office. This will give you an idea of what types of local or regional mineral deficiencies or toxicities you should keep an eye out for.

Second, send water from each of the cattle water sources for testing to get an idea of the mineral components in the water. Finally, each type of feed offered to the cattle should be analyzed for nutrient content. The results from a nutrient analysis will not only give us an idea of the vitamin and mineral content of each feed, but also provide information like protein, energy and fiber levels, which can help ensure we are meeting the dietary needs of our animals. Be sure to test for calcium, phosphorus, magnesium, potassium, sodium, sulfur and chloride.

Unfortunately, dietary input is only one piece of the puzzle. Individual animals require different things, and nature tends to work against us on occasion. No matter how hard we work to make sure we are doing the right thing when feeding our animals, there is always a chance we will encounter an issue here and there. The following list will help identify a few common vitamin and mineral deficiencies or toxicities that occur around calving time.

Milk fever is low blood calcium that can occur hours, days, or sometimes weeks before or after calving and is associated with using calcium for milk production (especially colostrum production) and depleting calcium levels needed for things like muscle function. Milk fever is most common in cows with high milk production. Calcium interacts with phosphorus and vitamin D, so an imbalance of either of these may also be to blame for symptoms of milk fever. Initial milk fever symptoms are muscle weakness and tremors.

The cow will have difficulty moving and walking. As the condition progresses, the cow will go down and will usually have a visible kink in her neck. Eventually, she will lie flat on her side. From the beginning, she will be drowsy, have a rapid but weak heartbeat and low temperature. Ultimately, milk fever will cause cardiac failure and death. Long-term calcium deficiency can present as abnormal bone growth or bone weakness.

Because phosphorus is tied closely to calcium, deficiency often mimics symptoms of calcium deficiency. However, phosphorus also plays a role in skeletal and muscular development, and can also present as diminished growth and poor reproductive ability. It is not only important to meet requirements, but to also balance the ratio of calcium to phosphorus intake at approximately 2 parts calcium to 1 part phosphorus.

Grass tetany is a magnesium deficiency in cattle that occurs when lush forages grow quickly, and the nutrients are diluted by the high moisture content. Adult cattle cannot easily access magnesium stored in their bones; therefore, magnesium must be provided to them in their diet. Grass tetany is most common in the spring, but can happen at any time during the growing season, such as during regrowth periods.

Keep an eye out for grass tetany when spring green-up occursFurthermore, grass tetany often occurs during calving and lactation, and may also be associated with a calcium deficiency, making it difficult to distinguish from milk fever. Early stages of grass tetany cause the animal to appear uncomfortable and stagger around. They often lay down and stand up repeatedly. In later stages, the animal will go down and lie flat on one side, exhibiting stiffness of muscles and convulsions with the head pulled back. If not treated, animals with grass tetany will likely die.

White muscle disease is associated with selenium or vitamin E deficiency. This deficiency causes muscle breakdown and affects young, rapidly growing calves. It can affect either the cardiac muscles or the skeletal muscles. The cardiac form of white muscle disease will come on rapidly, and the calf will exhibit a rapid heartbeat and difficulty breathing.

Typically, this form of the disease will end in death within 24 hours. Onset of the skeletal form is slower, and calves will exhibit stiffness and weakness of the muscles, causing them to only stand for short periods of time. They may also have difficulty breathing and swallowing feed.

While this list is not all-inclusive of the vitamin and mineral deficiencies (or toxicities) that may occur in cattle, these are some of the most common nutritional deficiencies that emerge during calving and lactation. If you encounter one of these vitamin or mineral deficiencies in your herd, act quickly and consult your veterinarian to ensure you have correctly identified the problem and treatment or prevention options.

If you notice overall poor performance, decreased reproductive ability or reduced growth within your herd, consult your veterinarian or extension educator to determine if it may be attributed to underlying nutritional imbalances. Administering a simple injection or supplying a feed supplement may improve your overall herd health and performance considerably. It is important to take time to make sure they are getting the nutrients they need. Here’s wishing you a quick and painless calving season.   end mark

PHOTO 1: Dietary input is only one piece of the puzzle when identifying nutritional health issues around calving time.

PHOTO 2: Keep an eye out for grass tetany when spring green-up occurs, and when calving and lactation season kicks in. Staff photos.

Melinda Ellison is the range livestock extension specialist at the Nancy M. Cummings Research, Extension and Education Center in the animal and veterinary science department at the University of Idaho. Email Melinda Ellison.

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