Free-Choice or Loose Mineral Supplementation
Free-choice or loose mineral supplementation is a commonly used method to provide supplemental minerals to cattle on pastures. This method provides a complete mineral supplement that is available to cattle at all times, including both macro- and microminerals and necessary vitamins such as vitamins A and E. For more information on vitamins, see the UK Cooperative Extension Service publication Vitamin Supplementation for Beef Cattle (ASC-248). Free-choice minerals are usually granular products designed to be fed in covered mineral feeders (Figure 1). It is important to carefully read the mineral tag on a free-choice mineral product to understand the quantity and quality of minerals being provided in the product. For more information on how to read a mineral tag, refer to the UK Cooperative Extension Service publication Reading the Fine Print: Understanding Mineral Tags (ASC-249). Free-choice minerals are typically formulated for a target intake of three to four ounces per head per day and contain 15 to 25 percent salt. The salt is included to meet cattle's desire to consume salt and meet sodium requirements, but it also helps to limit intake of the mineral product.
Free-choice minerals should be offered in a covered feeder to protect the mineral from precipitation, as many mineral sources
are in a salt form that may dissolve in water. These feeders should not be higher than 24 inches from the ground to allow calves adequate access to the mineral. It is a common misconception that calves do not require mineral supplementation; however, research shows that cow's milk is deficient in one or more minerals. There should be one mineral feeder for every 25 to 35 head. Mineral feeders should be placed in high-traffic areas where the herd is likely to visit routinely. A common suggestion is to locate mineral feeders near the water source or shade.
It is essential to monitor the intake of free-choice minerals. Table 5 shows how long a 50-pound bag of minerals should last, based on herd size and formulated target intake. It is important to note that mineral intake can vary based on several factors, including the weather, location, and number of mineral feeders. If mineral intake is lower than expected, consider adding a feeder, moving the feeder closer to a high-traffic area or closer to water, or trying a different product that may be more palatable. If mineral intake is too high, consider offering a salt block for 24 hours or adding five pounds of loose salt per 50 pounds of free-choice product for a short period of time. This can allow the herd to satisfy its craving for salt without overconsuming minerals, which can be expensive.
Salt-Based Blocks
Another common method of mineral supplementation is the use of salt-based blocks. However, this method does not provide
adequate concentrations of required macro- and microminerals and does not provide vitamins. These products are typically 95 to
99 percent salt. Even when a block product contains trace minerals, the low daily intake combined with the mineral concentrations included in the block place cattle at risk of developing mineral deficiencies. For these reasons, it is not typically recommended to utilize salt-based blocks for mineral supplementation. Another common mistake is providing a salt block along with a free-choice mineral supplement. When a salt block is provided, cattle may meet their desire to consume salt from the block and fail to visit or adequately consume minerals from a mineral feeder. This can also put cattle at risk of developing mineral deficiencies. An exception to this recommendation would be when providing salt to limit overconsumption of a free-choice mineral product, as mentioned previously.
Cafeteria-Style Mineral Supplementation
Although sometimes referred to as free-choice minerals, this style of mineral intake relies on placing individual minerals, or mixes containing two or three minerals, in their own containers or compartments within a feeder, versus putting a formulated mixed-mineral product into a single feeder. This style of mineral supplementation has been made popular through popular press articles and social media. No research has shown that this supplementation method is advantageous compared to feeding a formulated mix. This style of mineral supplementation is not recommended for several reasons. Cattle lack nutritional wisdom, which means they do not make nutritional decisions based on what is healthy for them or what their diet is lacking, but rather feed intake is driven solely by palatability. When cafeteria-style minerals are offered, those deemed more palatable will be the first to be consumed, and the herd will avoid consuming less palatable minerals that may be needed, such as magnesium oxide. Additionally, many minerals have complex interactions with one another, often referred to as antagonisms. When too much of one mineral is consumed, a deficiency of a second or third mineral can be induced, even if intake of that mineral is adequate. Figure 2 shows the complexity of these mineral antagonisms. A cafeteria-style program for providing minerals is not recommended due to the risk of developing mineral deficiencies because of poor mineral intake or mineral antagonisms.