When it comes to cattle mineral nutrition, it is about delivering the right amount to the animal. Most of the time, forages, especially actively growing forages, will provide adequate amounts of almost all minerals and vitamins. Mineral supplements are fed in cow-calf operations to account for the times when deficiencies in forage or hay do occur. However, it is important to know that too much mineral can cause reduced animal growth, reduced reproduction and death. Problems with excess trace mineral supplementation (especially copper and zinc) seem to be increasing.
Minerals, especially trace minerals, often get more credit or blame than they deserve for changes in pregnancy rates and animal performance. Protein and energy (aka calories) nutrition are responsible for the biggest changes in performance. A mineral supplement isn’t going to overcome a diet that is lacking in protein or energy. This is especially true when it comes to pregnancy rates. Body condition score just prior to calving has the biggest effect on cows coming into heat and getting bred.
A complete free-choice mineral supplement for grazing cattle will have four main components:
- Salt
- Macrominerals
- Trace minerals
- Vitamins A, E and sometimes D
Free-choice mineral supplements generally come as a loose meal in 50-pound bags. In addition, supplemental minerals might also be provided in tubs, liquids feeds or blocks. However, it is very rare to find a block that is formulated to serve as a complete mineral supplement. Most blocks are made of mainly salt and often lack important macrominerals and trace minerals in the desirable amounts or ratios.
If using tubs or liquid feeds, check to make sure they contain salt. If they don’t, then a source of plain white salt (e.g., white salt block or loose “mixing" salt) should also be provided along with the tub or liquid feed.
When providing mineral supplements, don’t overdo it. A well-designed, complete free-choice mineral supplement does not require multiple products to be fed at the same time. Feeding multiple products designed to deliver minerals (e.g., loose mineral, tub, liquid feed, block, etc.) at the same time is costly and, as mentioned earlier, can lead to reduced performance.
Additionally, if animals are consuming the targeted amount of a well-formulated mineral supplement, then giving them mineral injections or drenches can lead to higher levels of trace mineral absorption than desired.
