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Magnesium (Mg) in Powdered Milk Replacers



Dietary considerations


Magnesium is an abundant mineral in the body, and needed for 300+ biochemical reactions. Magnesium plays an integral part of providing bone structure and firmness, and also helps make teeth harder. At least 60% of the magnesium in the body is located in the bones and about 26% is in muscles. Additionally, it helps maintain normal muscle and nerve function, supports a healthy immune system, and is essential for many cellular functions (e.g., energy and protein production, cellular replication).


Magnesium concentration imbalances


Magnesium works closely with other minerals, such as calcium and phosphorus. Research continues on understanding the role, amount and balance of Magnesium. For example, some researchers reported that an increase of calcium supplements can lead to an increase in magnesium loss - unless they are balanced. Some also report that the use of calcium supplements concurrent with a magnesium deficiency may contribute to calcium deposits in the kidney and soft tissues, including joints. The role of magnesium is considered essential – even though there are many unknowns.


Milk replacer analysis


Magnesium concentrations are shown below by product. The average value for all samples of each product is shown, as well as the range of high and low values for all of the samples for that product. Most of the products are supplemented by magnesium sulfate as indicated on the package labeling. 


Since these concentrations are very small in absolute terms, the general variability should be considered in percentage terms. For example, Fox Valley 40/25, for the lots tested, has a range of +63% to -27% from its average concentration value. Another example is Esbilac® with a range of +75% to -63%.


Since the correct range of concentration values for all species are different, and since wild species milk composition is very limited, reference values for whole and lowfat dry milk are provided in the chart.


Products can be compared in absolute terms as well, such those with similar protein/fat concentrations. For example, Esbilac®, GME® and Zoologic®33/40, all similar in their 33/40 construct, show average concentrations, for the lots tested, of .08%, .05% and .04%, respectively.

Magnesium concentration chart2.jpg

Since averages can at times be misleading, a closer look at a few of the products where multiple test values are available between time periods, can reveal how the concentration values may have changed over time. Then if those changes are significant, either increase or decrease, the reader may want to focus on the most recent profile of the product. 


Even though some of the changes reflected below may be significant over time, simply trying to adjust with supplements requires considerable knowledge and has the potential to worsen an adverse situation. Please review the section on mineral supplementation in the minerals overview.

Magnesium change over time.jpg

References and further reading (not intended as an exhaustive list)


Brown, Susan. 2014. Key Minerals for Bone Health. Bone Nutrition. July.


Cashman, Kevin and Albert Flynn. 1999. Optimum Nutrition: Calcium, Manganese, and Phosphorus. Proceedings of the Nutrition Society. V. 58, pp. 477-487.


Castiglioni, Sara, et al. 2013. Magnesium and Osteoporosis: Current State of Knowledge and Future Research Directions. August; 5 (8), pp. 3022-33.


Nieves. 2005. Osteoporosis: the role of micronutrients. American Journal of Clinical Nutrition. V 81 (5), pp. 1232S-1239S.


Rude, Robert. 1998. Magnesium Deficiency: A Cause of Heterogenous Disease in Humans. Journal of Bone and Mineral Research. V 13 (4). 

The information included on this website for dietary minerals is extremely narrow in its scope and nature. It is limited to certain charts and graphs displaying content values (% of total) of various powdered milk replacers as tested by an independent chemical lab. Extremely brief overview information is provided as to the primary nutritional and medical benefits of each mineral, as well as a limited discussion of issues that may arise from concentration levels in the body that may be considered deficit or toxic. Entire textbooks on dietary minerals are written for the medical and veterinary professions, in addition to the internet providing ready access to both scholarly and popular literature. Some of those references are included above.


The data values presented above only represent the test values for the presence and concentration of the mineral conducted according to standard chemical testing methods in a controlled laboratory setting. Any point test value is accompanied by a measurement uncertainty range of +/-20%. The concentration values are in no measure an indication of how much of the mineral may be provided to an animal in reconstituted formula or its bioavailability (its degree of digestibility, absorption, or ultimate utilization). Additionally, no testing was performed as to the source of the mineral in the product (such as inorganic salts) or the grade of any added supplements containing the mineral.


What the data can do is inform the reader as to (1) concentration levels in a product as most recently tested (2) changes over time and between lots, and (3) comparisons of relative concentration levels between products. It is merely data that may serve as a starting point when deciding on a milk replacer product(s) and a recipe, or information to consider if certain medical symptoms appear that could be a result of absence or excess of a specific mineral in the formula. The reader is encouraged to consult veterinary or nutritional professionals prior to providing additional supplementation of any mineral.

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