Mineral Nutrition In The Cow: Reading The Mineral Tag & Bioavailability

Apr 18, 2016

By Adele Harty

SDSU Extension Cow/Calf Field Specialist

Mineral nutrition is vital to overall cow performance. Without an appropriate balance of minerals, cows may not perform as expected or could exhibit detrimental effects.

Two recent articles on iGrow have discussed macrominerals and trace minerals and the roles they play in cattle nutrition. This article will focus on reading the mineral tag to ensure that the supplement you are providing your cattle is meeting their nutritional needs. Not all mineral supplements are created equal and it is important to know what to look for in a mineral supplement and what you might want to avoid.

Identifying Mineral Needs

The first challenge with a mineral program is knowing what your cows need. This is driven by the feeds they eat as well as the water they drink and it changes throughout the year. Oftentimes, we may not think about the mineral contribution of the water to the diet, but it is very important, especially when water could be high in salt and sulfates. Ideally all feeds and water should be tested for mineral content to determine deficiencies, toxicities and interactions that may exist. Once this is determined, then mineral supplements can be sourced. Many companies have formulated minerals for specific regions or are willing to develop custom formulations for ranches. If you choose to use a mineral that has been formulated for a region, reading and understanding the feed tag becomes more critical.

Analyzing the Mineral Tag

As you analyze the mineral tag, there are a few key items to look at initially. How much salt does the product contain? Products that contain 10% salt or more don’t need additional salt and will result in an adequate daily intake of 3 to 4 oz. Mineral supplements that contain less than 5% salt are considered mineral concentrates with cattle consuming approximately the recommended 2 oz. per day. If using a mineral concentrate, free choice salt must be provided.

Next, take a look at the ingredient list to determine the type of mineral used in the supplement. Not all sources of minerals have the same bioavailability to the animal. For example, you could be spending extra money for a high copper mineral, but the copper is being provided by copper oxide, which is only 15% bioavailable. Therefore, the mineral tag may show that the supplement has 5000 ppm Cu, but the cattle will only utilize 750 ppm (15%) because it is supplied as copper oxide. On the other hand, if tribasic copper chloride is a source of Cu, its relative bioavailability is 115 which means Cu is 15% more available to the animal than that in copper sulfate, which is used as the standard (100%). A product with tribasic copper chloride will provide more Cu to the animal than a product with copper oxide or copper sulfate.

Inorganic & Organic Mineral Sources

Mineral sources are divided into two groups: inorganic and organic. Inorganic will be less expensive mineral sources, but are also typically less bioavailable than their organic counterparts. Generally speaking inorganic sulfates and chlorides are more available than oxides and carbonates. The exceptions to this are zinc oxide and magnesium oxide, both of which have a bioavailability of 100. Chelated minerals are those that are bound to an amino acid or other organic molecule, and their bioavailability exceeds 100. If animals are stressed or mineral antagonists are present in large amounts the extra price paid for chelated minerals may be justified. Chelated minerals will provide more value to cattle during weaning or other stressful periods, but their cost will likely exceed the benefits in a standard mineral program. See Table 1. below for a sample of mineral supplements, mineral concentration, bioavailability and mineral availability.

Table 1. Mineral concentrations and relative bioavailabilities of common mineral sources.

Supplement	Mineral concentration (MC, %)	Relative Bioavailability* (RV, %)	Mineral Availability (MC x RV)
Calcium
Calcium carbonate	38	100	38.0
Calcium chloride	31	125	38.75
Dicalcium phosphate	20	110	22.00
Limestone	36	90	32.40
Monocalcium phosphate	17	130	22.10
Cobalt
Cobaltous sulfate	21	100	21.00
Cobaltic oxide	73	20	14.60
Cobaltous carbonate	47	110	51.70
Cobaltous oxide	70	55	38.50
Copper
Cupric sulfate	25	100	25.00
Cupric chloride (tribasic)	58	115	66.70
Cupric oxide	75	15	11.25
Copper (organic form)	?	130	?
Iodine
Potassium iodate	69	100	69.00
Calcium iodate	64	95	60.80
Ethylenediamine (EDDI)	80	105	84.00
Magnesium
Magnesium sulfate	20	100	20.00
Magnesium oxide	55	100	55.00
Manganese
Manganese sulfate	30	100	30.00
Manganese carbonate	46	30	13.80
Manganese (organic form)	?	176	?
Phosphorus
Defluorinated phosphate	12	80	9.60
Dicalcium phosphate	18	85	15.30
Selenium
Sodium selenite	45	100	45.00
Sodium
Sodium chloride	40	100	40.00
Sodium bicarbonate	27	95	25.65
Zinc
Zinc sulfate	36	100	36.00
Zinc carbonate	56	60	33.60
Zinc oxide	72	100	72.00
Zinc (organic form)	?	159 to 206	?