Mineral Nutrition for Dairy Herds

Minerals make up a small share of a ration but affect bones, milk, fertility, immunity and calving. A good mineral program is planned, tested and checked, not left to habit.

Key points

Cows need both macro and trace minerals, and each herd's forage and water supply differ.
Test forages and balance minerals using your own numbers.
Both deficiency and excess cause problems, so signs need veterinary and nutritionist investigation.
Deliver minerals consistently through the TMR and keep records of what goes in.

Macro minerals and trace minerals

Dairy cows need minerals in two groups. Macro minerals, such as calcium, phosphorus, magnesium, potassium, sodium, chloride and sulfur, are needed in larger amounts. Trace minerals, such as zinc, copper, manganese, selenium, cobalt and iodine, are needed in tiny amounts but matter a great deal.

Both groups come from forages, grains, byproducts, water and the mineral premix. Each source varies from farm to farm and year to year, so guessing is a poor strategy.

Think of the premix as a prescription for your forages. When forage changes, the premix should be reviewed too, because last year's balance may not hold.

Start with what the feeds supply

Forage analysis shows what the base ration already provides. Mineral content varies with soil, crop, stage of harvest and fertilizer history. A premix that fits one farm's forage may be a poor fit for another.

Send forage samples for analysis and keep results organized by field and harvest. Ask the nutritionist to balance minerals using your numbers, not book averages.

Keep in mind that feed labels, guaranteed analyses and ingredient lists are tools for comparing products. Ask the supplier to explain anything on a tag that you do not understand.

Signs of deficiency and excess

Both too little and too much can cause trouble. A shortage can show as poor fertility, weak immunity, retained placentas, slow growth in young stock, or poor hoof and coat condition. Excess can interfere with absorption of other minerals, and some minerals are toxic at high levels.

These signs have many possible causes, so use them as a reason to investigate, not to diagnose by yourself.

Repeat breeders or poor conception
Retained placentas and weak newborn calves
Poor hair coat, dull skin or lameness
Cows licking or chewing at objects
Milk fever or downer cows around calving

Dry cow minerals deserve special attention

Calcium and the balance of charged minerals in a dry cow ration influence how well she handles the start of lactation. Dry cow minerals are often handled differently from those for milking cows, and the ration may be built with a specific goal in mind.

Work these decisions out with the nutritionist well before the close-up group starts calving. Mistakes here show up as sick fresh cows, which is an expensive way to learn.

Heifers and young stock need a mineral plan as well, because growth, bone and immune function all depend on a steady supply during the years before first calving.

Delivering minerals consistently

A mineral mix only works if cows actually eat it in the amounts planned. Free-choice minerals can lead to wide variation between cows, with some eating far too much and others almost none. Minerals mixed into a TMR are far more consistent.

Handling matters as much as the formula. A good premix is wasted if it is left in a damp shed or scooped by eye.

Weigh and record mineral mix additions at the mixer
Store mineral bags dry and labeled
Check that premixes are not clumped or caked
Never feed minerals made for other species
Follow label directions for anything fed to cattle

Records worth keeping

Mineral problems build slowly and show up late. Records are the only way to connect a problem in the fresh pen or the breeding barn to a decision made months earlier in the feed room.

Keep a simple file that you and the nutritionist can both read. It does not need to be fancy. A notebook kept in the feed room works if it is used every time.

Review it a few times a year and whenever a new problem appears. Patterns that are invisible week to week become clear over a season.

Forage and water test results by date
Premix brand, batch and feeding rate
Dates of ration changes
Health events around calving
Breeding and pregnancy results

Common mistakes and what to ask

Typical mistakes include doubling up on supplements that overlap, ignoring water as a mineral source, and changing premix brands without a ration rebalance. Another is relying on a single feed rep when a veterinarian or independent nutritionist could offer a second opinion.

If problems persist, the veterinarian may use blood, liver or tissue testing to check mineral status.

What minerals do our forages and water supply?
Is any mineral near or above its safe upper limit?
Is the dry cow program separate from the milking program?
How often should we retest forages and review the premix?

When to get help: Ask your nutritionist to review the ration and any change before you make it, and call your veterinarian if cows go off feed, show loose manure, lose condition or develop lameness. If any cow is treated, follow the label or veterinarian withdrawal times for milk and meat exactly.

Sources and further reading

Organization homepages are linked so you can search them for current guidance on this topic.

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