published in


June 2013

Free Choice Intake of Salt-Based Trace Mineral Supplements

Ona Report - Dr., John Arthington

For questions or comments regarding this publication contact: John Arthington 

Cattle have a nutritional need for sodium and chlorine.  This requirement has been realized for centuries due to picture of Indicus Cows consuming salta natural craving for common salt.  Collectively, these elements function as electrolytes in body fluids and are essential for nutrient metabolism.  Early signs of sodium and chlorine deficiency include a craving for salt, demonstrated by the licking of wood, soil, and sweat from other animals.  A prolonged deficiency causes loss of appetite, decreased growth, unthrifty appearance, reduced milk production, and loss of weight.  Sodium is the most limiting of the two minerals in typical cattle diets, so supplementation is almost always required.  Common salt is the most widely utilized source for sodium supplementation.
As the summer approaches our Florida beef cows begin to increase their voluntary consumption of free-choice mineral (see Figure1, below).  A common misconception is that cattle will consume free-choice mineral at the amount needed to meet their requirements, thus if cattle are consuming more mineral than usual, it must be due to an increased need.  This is not true.  Cattle only have a nutritional wisdom to consume salt at or above the amount of nutritional requirement.  Because salt is used as a carrier for most of our free-choice mineral supplements, the increased summer intake is only a reflection of an increased craving for salt.  This seasonal change in mineral intake pattern is related to, 1) an increased salt requirement during the summer months, and 2) an unexplained craving for salt.  If allowed free choice access, grazing cows will often consume mineral supplement in far excess of their requirement during these summer months.  This increased intake will not hurt the cowherd; however, it is also important to understand that it also will not improve production.  It is a costly waste that can be lessened by a couple different management strategies. 

Line graph showing percent of weekly refusal of free-choice minerals over 3 consecutive years.

Diluting free-choice mineral supplements with straight stock salt.   White stock salt is not free, but it is much less expensive than a fully fortified mineral supplement.  So, if you are feeding a supplement formulated for a 2 oz/d intake and the cows are actually consuming 4 to 6 oz/d (typical for many summer month situations), then consider mixing your mineral supplement with salt at a 50:50 ratio.  Thus, a 4 oz/d intake of the blended mixture will result in the originally targeted consumption rate of 2 oz/d of the complete mineral premix.  This management option can greatly reduce your annual cowherd mineral costs without impacting production.  Remember, when using this management strategy; do not feed the white stock salt and mineral supplement separately - instead, hand-mix the two together.  Also, it is important to continually monitor intake.  As voluntary intake declines, you will need to reduce the inclusion of white stock salt with the goal of regulating the intake of your mineral supplement as close as possible to the formulation’s feeding instructions.  By monitoring and recording mineral intake each week, a record can be obtained that will fairly repeatable on an annual basis with the same pastures and herd of cows. 

Controlled feeding of minerals.  This management strategy involves the formulation of a palatable, grain-based supplement fortified with essential minerals.  This method of mineral feeding can be particularly useful when cattle are not attracted to supplemental salt, which can be observed in areas with saltwater intrusion into drinking water.  Under these situations, cattle may not adequately consume free-choice mineral supplements, and thus, lack essential minerals such as copper, cobalt and zinc.  When offered a minimum of twice weekly, this mineral-fortified supplement can be an effective, efficient tool for delivering supplemental minerals to the cowherd.  For best results, the supplement should be formulated into a range cube or pellet and fed on the ground, or as a loose mix supplement offered in feed bunks.  Molasses-based liquid formulations are also available.  Maximum intake should be limited to ¼ to ½ lb per cow at each feeding for the dry supplements and less than 1 lb per day for the liquid supplements.  The mineral specifications can vary greatly depending on the amount of product being consumed and the frequency of feeding.  Free choice white stock salt should be offered to the cowherd at all times.