COMMENT: The dry period is one of the most important stages of a dairy cows lactation cycle. It gives the cows a chance to recover from the previous lactation, while also helping to lay strong foundations for milk production and health of the cow during the next cycle.

Research has proven time and again that dairy cows require trace mineral supplementation on a daily basis. This is necessary to minimise metabolic problems, including both clinical and sub clinical milk fever, retained placenta, ketosis, lameness, displaced abomasums, mastitis and somatic cell count problems.

The mineral status of the cow also has a large effect on lazy calving, calving difficulties, calf death and poor calf health. Maternal deficiencies of trace minerals and vitamin E in late pregnancy can compromise the immune system of the calf resulting in an increased susceptibility of scour, pneumonia and so on.

At the beginning of the dry cow period some analysis should be undertaken to establish what mineral deficiencies are present within the herd. A good place to start is with a bulk milk sample taken in the last few weeks before the herd is dry. Bloods should also be analysed for mineral status from a random sample within the herd (approx five per cent), making sure not to forget about first time heifers due to calf down in the spring. In order to build up a complete picture an analysis of feed ration should also be completed.

Once results are analysed a mineral plan should be drawn up. Depending on different regions of the country (or even within the same parish!), mineral status can differ greatly. This is why it is important to not simply buy an off the shelf mineral, rather get a mineral tailored to your specific requirements.

Below are the main minerals that are shown to be deficient in Irish herds:

Magnesium is a vital mineral for dry cows and essential in all herd. This plays an important role in milk fever prevention (Calcium deficiency) as it is required for the production of hormones important for the absorption of calcium from the gut and the mobilisation of calcium from the bone. Magnesium is also essential for growth, repair of body tissue and bone development.

Selenium deficiency is common in most herds. Marginal deficiencies in Selenium can cause retained placenta, an increase in mastitis duration and severity while also resulting in reduced reproductive performance.

Iodine deficiency is the most prevalent deficiency in Irish herds, and is an essential component in growth, reproduction, circulation and muscle function to name but a few. One of the main problems associated with iodine deficiency is weak or dead calves. It is essential the iodine supplementation be carried out on an ongoing basis, as it is extremely short acting in the body.

Copper deficiency on its own is rare, and a deficiency in the animal is most likely due to high antagonism by Sulphur, Iron and especially Molybdenum in the rumen. Copper is a key component for many actions within the body including bone formation, proper cardiac function, immune system, fertility, and growth rate. Overfeeding copper can have a negative impact on all of these functions therefore it is vital that some analysis of the status of the cow be obtained first.

Zinc is essential in the role of the immune system and can improve hoof hardness, decrease sole abscesses and reduce somatic cell counts.

Vitamin E is required for good health and the immune system of the cow and calf. It also plays an important role in preventing retained placenta.

Mineral deficiencies

Methods of supplementing dry cow minerals vary from licks/buckets, dry minerals, bolus or feeding through the water. When choosing a delivery method take into account possible variation of intake between animals, labour and availability of minerals to the animal. Minerals fed in the liquid format have been proven to be more available for absorption, which results in an improved mineral status in the animal. Ensure these products are purchased from reputable sources, as mineral products can contain significant impurities (eg heavy metals), which can be dangerous and do not provide a benefit. In addition, prior treatment of minerals products (eg heat treatment or cooking) may render the mineral less available to the animal.

A successful lactation begins with optimal trace mineral nutrition. Attention to detail during the dry period is important for a profitable, productive dairy herd. The dry period should be regarded as the beginning of the next lactation.

By Padraig Hennessy, Terra liquid Minerals 

Pictured housed dairy cows on silage. Photo O’Gorman Photography