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Global shortage of Magnesium could affect milk production
August 28, 2017

Dairy farmers are being reminded to check magnesium levels in their herds to avoid a drop in milk production as a global shortage of the mineral continues.

A constant 5mph breeze flows through the barn

A constant 5mph breeze flows through the barn

Fed as a supplement to dairy cattle, 80 per cent of the world’s magnesium comes from China, where a crackdown on pollution late last year forced the temporary closure of plants producing it.

As a result, the dairy industry was facing a significant shortage of magnesium oxide (MgO), important for rumen function, metabolic processes and milk production.
Taranaki Veterinary Centre chief executive Stephen Hopkinson said supply in the region was down 15-25 per cent.

Low magnesium levels could reduce milk production and farmers who had cut back on dose rates should have some of their animals blood tested, he said.

“Even if you have had no milk fever, it’s worth checking the magnesium status of the cows because low levels will affect milk production,” he said.

Regardless of herd size, 10 cows should have blood samples taken.

“Four to six-year-olds are the most at risk group because of milk production, ” Hopkinson said.

“Choose animals that have been calved at least four to six weeks.”

Once a deficiency was identified, it could be corrected quite quickly, he said.

“In the past, we’ve seen milk production increase by 10 per cent within 48 hours.”

Although the shortage was expected to be temporary, Hopkinson urged farmers to use the MgO they had carefully and accurately calculate their cows’ daily dose rate.

“A cow needs to eat 20-30 grams of MgO per day so you have to then estimate what the wastage factor is depending on your method of feeding,” he said.

“Only give the exact amount you have calculated you need each day. If you calculate that you need 3.25 bags per day, then give exactly this amount. Don’t round up to 3.5 or even four bags because it’s convenient.”

Hopkinson advised against putting MgO on pasture during wet weather as it was likely to be completely washed away.

Other ways to save included:
Spreading MgO over hay or silage being fed out or on top of palm kernel in the trailers, both of which would have lower wastage than pasture dusting.

Using magnesium sulphate or chloride in water troughs so less MgO needed to be used on pasture. Water uptakes were very low in winter and when there was rain, but farmers could save 25-30 per cent of their MgO if they could get 50 grams of MgSO4 or MgCl2 per cow per day via an in-line water dispenser.

Avoiding paddocks that had effluent sprayed in them while using lower doses of MgO. These paddocks had very high potassium levels which prevented magnesium absorption from the gut.

Using lime flour in the colostrum and milking mob for milk fever prevention. While magnesium is required by the cow particularly for milk production, lime (calcium) is far better at preventing milk fever.

 

Source: NZFarmer



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