by: Stephen B. Blezinger
Ph.D., PAS

Most cattle producers will tell you they have some type of mineral program. This might range from a “white salt block and a yellow salt block” on to a full blown, custom-designed mineral with all the bells and whistles and then some. In general, when selecting a mineral program the typical producer does so with the cow in mind. We know that minerals are involved in a long list of performance parameters including health, reproduction, milk production, weight gains in calves, etc. The better the program is designed the less likely the herd is to encounter production or health problems.

One of the most critical components of the breeding program, the herd bull, is often neglected when considering mineral nutrition on the ranch. It's generally assumed that if a program is meeting the cow's requirements it should do the same for the bull. A large part of this is because outside of the actual breeding season when bulls are with the cows and have a specific job to do, we tend to ignore these guys. That is, as long as they are not tearing down fences or destroying feeders or fighting and hurting each other. But the bull makes up 50 percent of each calf. And getting the cow bred is dependent on the bull being fully functional. In many cases, the functionality of the bull can be dependent on his mineral status.

Let's take a few minutes and review mineral nutrition as it affects this important member of your breeding program. Then we can define some steps for the producer to take to insure the bulls are “locked and loaded.”

Mineral Basics

All cattle, including bulls, have requirements for key minerals in their diet. To review briefly, the areas of necessity include:

Calcium (Ca): Formation/ maintenance of bones and teeth, nerve transmission/activity, muscle integrity, involved with P and Vitamin D to maintain blood Ca levels.

Phosphorus (P): Formation/ maintenance of bones and teeth, component of DNA, energy metabolism (component of ATP, ADP), reproduction, growth.

Potassium (K): Muscle integrity, nerve transmission, water balance, organ function, appetite, growth.

Magnesium (Mg): Enzymatic activity related to a wide range of reactions in the body ranging from the metabolism of glucose for energy needs to the replication of DNA, nerve transmission and integrity, bone development, appetite.

Sulfur (S): Required for protein, vitamin and enzyme synthesis in the body and in the rumen by the bacterial population, muscle development.

Chlorine (Cl): Functions with Na to maintain balance of fluids (water) in the body, production of hydrochloric acid in the abomasums, CO2 transport.

Sodium (Na): Functions with CL to maintain balance of fluids (water) in the body, muscle and nerve function, transport of key nutrients into the cells.

Cobalt (Co): Required in the rumen for Vitamin B-12 production. B-12 is required for energy metabolism in the animal, appetite.

Copper (Cu): Enzymatic synthesis and activity, cellular energy production, bone development, immune system function, reproduction, skin and hoof health, hair coat coloration.

Iodine (I): Production of thyroxin which regulates metabolic rate, reproduction, skin and hoof health.

Iron (Fe): Enzyme systems involved in energy metabolism, oxygen carrying capacity of red blood cells, feed intake.

Manganese (Mn): Enzyme synthesis and activity, structural development, cartilage production and development, bone development, immune system function, skin and hoof health.

Selenium (Se): Enzyme synthesis and activity, fertility, immune system function, hair coat, muscle development and integrity, Vitamin E metabolism and function.

Zinc (Zn): Enzymatic synthesis and activity, muscle development, immune system function, male reproductive tissue development and function, spermatozoa production and integrity, appetite, immune system function, skin, hoof and hair coat health.

While this list is not comprehensive it does provide an idea of the extensive and critical roles minerals play in growth, development and performance of the bull. Extensive data since the late 80's has shown that the importance of proper mineral availability extends back to the point of conception and its developmental stages in the uterus, particularly embryonic and fetal reproductive tissues.

Through gestation, birth and early developmental stages, synthesis of muscle and bone are obviously important as well as genetic and phenotypic expression. These are all highly dependent on mineral status in the bull calf. So initially, the producer needs to insure that the dam is properly supplemented. The producer needs to recognize that milk is actually a poor source of some minerals, particularly trace minerals such as Cu, Mn and Zn. When the calf is born whatever his mineral status is will need to hold him until he can begin consuming supplemental sources. If he is born in a low or deficient status his performance will suffer at some point and at some level before he can begin replenishing these stores. Adequate levels of critical minerals, especially the trace minerals are needed during the first few months of life to support growth and development (especially reproductive tissues) and immune response.

As the bull calf reaches weaning and puberty it is important that a well designed mineral program be in place. Good management practices and provision of balanced nutrients are critical to developing and maintaining bull fertility. In addition to protein, energy and macro minerals such as Ca, P, K and Mg, adequate trace mineral intake and absorption is required for reproduction. Reproductive performance may be greatly affected if zinc, copper, manganese or selenium levels are marginal or deficient.

As mentioned, we regularly focus on mineral deficiency effects on the female. Common Cu deficiency symptoms in cows include delayed estrus, decreased conception rates, infertility and early embryonic death resulting in more open cows in the fall. Inadequate Zn levels are associated with decreased fertility, increased dystocia and retained placentas.

In bulls, zinc deficiency causes lower fertility due to poor sperm quality and quantity and reduced scrotal circumference. Male reproductive performance is also affected by low Mn status which can inhibit libido and lowers spermatozoa numbers. Another consideration for bull fertility is bone soundness and the ability to travel. Zinc, copper and manganese are needed for skeletal development and maintenance as well as hoof integrity. A bull suffering from lameness or joint problems will breed fewer cows. Selenium deficiency in bulls decreases spermatogenesis, the development and maturation process for sperm.

Planning and Managing the Mineral Program for Bulls

Aside from Ca and P, there are no specific mineral requirements documented for bulls outside of those for beef cattle in general (Beef NRC 2000). Mineral requirements are based, for the most part, on bodyweight but there are multipliers related to breed type, production stage, dry matter intake or environmental factors.

Here are some guidelines for planning and managing a mineral program for bulls:

As with all cattle, base mineral programs on the forages of your operation. Take periodic samples of pastures, hays and silages to determine the mineral content. The forages provide the foundation levels. Knowing what is already there helps determine what else is needed to provide a balanced mineral supply. Once you have your forage assays, work with a qualified nutritionist to formulate a mineral supplement for your cattle herd.

Insure that the supplement is palatable and readily consumed. Typical mineral consumption may range from 2 to 4 ounces per head per day although mature bulls, which are commonly larger in frame and body weight, may consume more, potentially 6 or more ounces per day. Keep product available consistently year-round and keep a log of consumption. If intake changes, look for reasons why. Mineral intake commonly is a reflection of pasture or forage quality and quantity. Availability of other supplements can also affect mineral intake. These need to be taken into account.

Manage the feeders. Use a feeder that protects the supplement from the elements. Place the feeders near travel paths, resting areas or water sources. If consumption is too high move feeders farther away from these areas. Feeders used in bull pastures need to be strong and tolerant of abuse. If possible, anchor the feeder to the ground to prevent it being knocked over.

The supplement itself should be formulated to balance the forage base and take into account any other mineral sources that are fed including tubs, liquids, etc. About 60 days prior to turning bulls in with females, it is recommended to add, as part of the trace mineral component, organic or chelated sources of C, Zn, Mn and Se. These sources improve the availability of these nutrients which are particularly important during this period. It takes 60 to 90 days for spermatozoa to fully develop in the bull. Insuring adequate or better levels of trace minerals, especially Zn helps promote proper sperm quality and quantity.

Use of an injectable trace mineral prior to the breeding season has been shown to improve reproductive performance in bulls. Providing injections 60 to 90 days prior to the breeding season and two or three more times during the year helps maintain status of Cu, Mn, Se and Zn in the animal, all of which play a role in reproductive function.


Breeding performance in your bulls is critical. Giving proper attention to the mineral component of their nutritional program helps insure their growth and development when they are young and optimal performance during the breeding season. This discussion is not suggesting that bulls need a different mineral supplement or program than the cows. However, the mineral needs of the bull are also of significant concern and need to be properly balanced. And as mentioned, given that the bull is 50 percent of every calf, particular attention should be given to his mineral and overall nutrient requirements.

Copyright 2014 – Dr. Stephen B. Blezinger. Dr. Steve Blezinger is a management and nutritional consultant with an office in Sulphur Springs, TX. He can be reached at or at (903) 352-3475. For more information please visit us on at www.facebook/reveillelivestockconcepts.

As an aside, given the focus of this issue, it makes sense to comment on some of the idiosyncrasies relevant to Brahman cattle and particularly Brahman bulls:

There are a few factors that may play a role in the mineral requirements for Brahman cattle. First, Brahman or Bos Indicus cattle in general, have skin that is characterized by the presence of sweat glands as opposed to English and European breeds, which do not. The presence of the sweat glands is one primary factor contributing to the animal's heat tolerance.

However, the ability to sweat and dissipate heat also would suggest that the Brahman animal may also lose greater amounts of electrolytes such as K, Na and Cl. During periods of high temperatures it would make sense to supplement these minerals to a greater extent for Brahman cattle.

Secondly, there is research that suggests that Brahman cattle may have a greater sensitivity to Cu. As such, it would make sense to take care when supplementing Cu and not provide this trace mineral in excess.

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