Some things change over time, and others don’t, with one certainty being the daily demand for magnesium by dairy cows, particularly prior to calving.

Without adequate daily intake of magnesium a wide range of health problems occur – at one end of the scale lower milksolid production, at the other end unnecessary deaths.

The factor most mentioned, however, is the time wasted in spring dealing with sick animals, and the sense of frustration that arises from having followed best advice, and yet the problems persist.

There are, however, a growing number of farmers for whom these issues simply don’t exist. For them an animal requiring treatment is worthy of note because it’s a rare occurrence, and they operate properties where Golden Bay dolomite is applied once a year, usually in autumn.

Although it is true that older animals, particularly if they are a Jersey or have a Jersey background, are more likely to suffer, our experience is that even purebred Jersey herds on such pasture have a similarly low incidence of metabolic disorders in spring.

Weather conditions also play a major role in calcium/magnesium related problems.  Leaf magnesium concentrations vary, being highest in periods of direct sunlight.  At these times the leaf content of pasture grasses may be as high as 0.25%, and animals fed well on this feed are receiving sufficient magnesium each day.

Magnesium concentrations decline in periods of wet cold weather.  Animals may eat less and, if another source of magnesium is not available, problems can still arise.

The most effective supplement is high quality meadow hay harvested from land that also receives an annual application of dolomite.  Hay contains the fibre essential for good rumen function, as well as useful energy and oils contained in the seed.

As one farmer recently stated, “No matter how good the salad is, it’s great to have some bread and pastry.” And where hay is made available, animals only eat sufficient to meet their requirements at that time.

Another reason for the effectiveness of dolomite spread at 220kg/ha in autumn is the calcium that is also applied.  Calcium/magnesium related metabolics are nearly always the result of an imbalance of the two elements, and because dolomite contains both in the ratio required by grasses its effect is extraordinary.

There is also the obvious advantage of receiving magnesium in every mouthful of feed rather than relying on it being provided via the water system, or as dust on the leaf of a plant.   As Professor Tom Walker wrote, “It makes good sense to me to correct animal deficiencies through the soil and the plant.”

When bulk deliveries of dolomite direct to farm started twenty-six years ago, most went to what were large herds at the time, those of over three hundred cows, as even on highly magnesium deficient country a single autumn application over the whole property markedly reduced the incidence of problems, reducing the reliance on variable intakes from dusting or water in troughs.

A further advantage of dolomite is the pH or ‘liming’ effect.  Dolomite contains 11.5% magnesium, and 24% calcium and has a slightly higher liming effect than the same quantity of lime.  28 tonnes of dolomite has the liming effect of approximately 30 tonnes of high quality agricultural lime.

It is available throughout the country and, if not already in stock at the major companies, it can be delivered in whatever quantity is required within a matter of days.  It may be added to a non-nitrogen fertiliser mix or spread separately, with a typical truck and trailer load sufficient for 127ha.

There are those that state that dolomite is expensive.  When higher production and less deaths are factored in, dolomite is one of the few fertiliser products that provides an almost immediate financial benefit. However the most satisfying aspect may be the peace of mind that comes from knowing that your valuable animals are receiving the benefits from the most effective magnesium fertiliser available and which is locally sourced.

For more information call Peter on 0800 4Dolomite (0800 436 566).

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