Pre-calver minerals should be fed to pregnant cows four to six weeks before calving. This means for early spring-calving herds, minerals should have been introduced before Christmas, while for later spring-calving herds it is time for this supplementation to be introduced now.

Function of minerals

The function of minerals for an animal can be divided into four main categories:

  • Skeletal development – calcium, phosphorous, magnesium.
  • Energy – phosphorous, copper, zinc, manganese, Se.
  • Milk production – calcium.

  • Bodily functions – Magnesium, Potassium, Sodium, Chlorine, Sulphur, Cobalt, Iodine, Iron.

    • Feeding minerals

    Minerals are most commonly fed by dusting on top of the silage at feeding time. However, other options include through water systems, molassed mineral buckets and/or a carrier ration. Furthermore, trace elements can be supplied in boluses, but this method will not cover for major elements.

    Where minerals are being dusted on silage or fed through a carrier ration, it is vital to ensure there is enough feed space for each animal. More often than not, it is the weaker animal that is bullied away from the feed face where space is limited, leaving her at risk of receiving no minerals.

    Mineral composition

    The table below gives a sample breakdown of the major elements, trace elements and the vitamins to look for in a pre-calver mineral mix, as well as the recommended quantities of each.

    Different brands of minerals will specify different feeding rates depending on the concentration of the mix. This will usually be around 100g to 120g per cow, daily. Always allocate according to the specified feeding rate and use a weighing scales and a designated utensil to do this.

    It is also very important to consider the mineral composition of the silage. In general, major elements in grass tend to match animal requirements but deficiencies can occur. On the other hand, trace element levels in grass are typically lower than required and consequently need to be supplemented at key periods during the year, including pre-calving. While pre-calver minerals are designed to do exactly this, a significant deficiency of some trace elements may require extra supplementation in the form of boluses or pour-ons for example.