MAG12-A new way to boost butterfats

Posted by rebecca on Jul 17, 2017, 11:26 AM

Butterfats are often depressed at grazing and there are a number of reasons for this, many of which are well known. Grazing diets are commonly low in fibre which reduces butterfat production and milk fat synthesis will be blocked if rumen pH falls due to SARA. If we see a significant grazing flush, the fat produced is diluted across more litres leading to lower percentages. What is less widely understood is that low magnesium levels can lead to lower milk quality too.

Magnesium is a major macro-nutrient, vital for nerve, muscle and bone formation. Around 50% of magnesium in cows is found in the bone which is not a readily available source meaning supplementation is required.

In the adult cow, magnesium is absorbed from the rumen and reticulum. There is no absorption beyond this point.

Conventional magnesium sources such as calcined magnesite are actually poorly absorbed and survive to the hind gut where they can cause irritation.

Effective magnesium absorption depends entirely on whether magnesium can solubilise in the rumen fluid. Crucially magnesium sources need to be soluble at the pH of the rumen, which when cows are at grass can be less than pH 5.2.

MAG12 is a breakthrough product. It is a natural source of minerals with high solubility, achieving 99% magnesium solubility in the rumen. By comparison, traditional magnesium oxide sources are typically 7 - 23% soluble in the rumen. This superior solubility reduces scouring associated with traditional magnesium sources and also provides a rumen buffering capacity which is an added benefit with grazing cows.

Trials show benefit

Using MAG12 in place of calcined magnesite leads to better performance in dairy cows. In trials at SRUC in 2011 butterfat and protein were both improved when MAG12 was used.


In the trial, cows were split into two groups that were grazed together to ensure access to identical grazing. One group received 60g/h/d of calcined magnesite, the other group received 12g/h/d of MAG12. The results were significant

• Increased milk yield (+1.1Kg/day).

• Higher butterfat yield (+103g/day).

• Improved butterfat composition(+1.9g/kg).

• Higher milk protein yield (+79g/day).

• Improved milk protein composition(+1.3g/kg).

These results have been consistently reproduced on farm.

MAG12 is now available in our Butterboost compound feed.

To learn more about MAG12, talk to your Feed Specialist.


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