Vet's perspective

Feb 24, 2012
by WLJ

Nutritional requirements for your cowherd


As some herds approach the calving season, producers are preparing for the calf crop as well as the next season. However, how many ranchers are considering the importance of vitamins and minerals in their herds’ daily rations?

Are your cattle prepared for the spring calving season? With all of the efforts that are put forth during basic cattle management, it can be easy to forget the small stuff. One of the “small” but very important aspects of nutrition involves adequate mineral intake. Minerals are solid chemical compounds that, when given in proper amounts, will interact with normal biological processes in the body in order to maintain nerve function, digestion, hormone control, and several other pathways. The minerals of utmost concern for successful reproduction are: phosphorus, calcium, copper, cobalt, iodine, selenium, zinc and manganese.

Both vitamins and minerals are crucial role-players in the physiological balance of nutritional pathways in regards to fetal development and growth, immunity and adequate weight management. The following vitamins and minerals are critical components of a healthy diet balance.

One of the first minerals any efficient producer will consider is calcium. The power-mineral aids in muscle and bone development and function, as well as helps prevent calving difficulty, the incidence of retained placentas and prolapses, and milk production. A cow’s calcium requirement can increase by over 20 percent during the last half of gestation, and by 40 percent after calving takes place.

A second important macro-mineral is phosphorus.

Calcium works in close connection with phosphorus for bone and tissue development as well as milk production. Aim for approximately 5 percent phosphorus in supplement minerals. Keep in mind that minerals can have normal interactions that affect their absorption in the intestinal tract. It is very important to have a calcium to phosphorus balance of 1.5:1 for best results.

Potassium is the third most abundant mineral in the body and is involved with acid-base balance, nerve conduction, water balance, and oxygen transport, to name a few of the important roles. Potassium is not stored in the body in large quantities, but most cattle are able to receive adequate amounts of the mineral through forage. If your pasture is ‘less than lush,’ then supplementation may be a good part of the nutrition program.

Minerals that play a part in enzyme activation and function as well as energy metabolism, such as copper, selenium and zinc, are critical in reproductive aged cattle. Nutritionists recommend adding these minerals into a ration in their ‘chelated’ form for the best absorption within the intestinal tract.

Both zinc and vitamin A have demonstrated a positive impact on fetal brain development and prevention of weak, blind, unthrifty calves due to deficiencies during gestation.

Along with vitamin A, its cohort vitamin E works in disease resistance and immunity enhancement. Selenium adds a role as well with its antioxidant abilities. Deficiencies in selenium and vitamin E may be demonstrated in young calves as the form of White Muscle Disease, with marked muscle weakness. Selenium is a trace mineral that can be deficient as well as toxic, due to its narrow safety margin. A deficiency of this important mineral (along with its cohort, vitamin E) can result in early embryonic death, weak calves, cystic ovaries and an increased incidence of retained placentas.

One of the more notable minerals associated with reproductive parameters, as well as growth and immune function, is copper.

This particular mineral plays a very important role as a co-factor for numerous enzymes functioning throughout the body. Research has demonstrated decreased conception rates, altered embryo survival, lower gestation rates, abnormal semen quality, and decreased ovulation all to be associated with improper copper utilization. Often, copper is deficient due to increased sulfate and molybdenum levels; these minerals interact with copper and tie up the ability for absorption within the animal’s system.

Another easily missed mineral is manganese. Deficiencies are also associated with decreased enzyme function and can present as suppressed conception rates, delayed estrus cycles, and even abortions and malformed calves.

Manganese has also reportedly been associated with altered estrogen and progesterone levels, possibly leading to cystic ovaries.

In addition, expert recommendations are to feed minerals and supplements that are no older than six months since purchase. If you are unsure of whether a product is suitable, check for an expiration date on the label.

Bioavailability, or the ability for a body to digest and utilize minerals, is very dependent upon the geographic region. Consult your local extension agent or veterinarian in order to analyze nutrition needs for your livestock as well as test water and feed for increased or decreased nutritional value. Cattle growth and performance can be compromised if a quality nutrition program is not in place.—Dr. Genevieve Grammer [Dr. Genevieve Grammer is a mixed-species veterinarian practicing in eastern Colorado. Please direct correspondence to drgigi19@]