What minerals are required by the dairy cow during the dry period?

Dairy farmers are being reminded of the important role of dry cow management, in particular nutrition, when looking to the future in terms of health and productivity.

This was the message from the Keenan workshop held in Co. Wicklow, on Thursday last, November 23. The workshops are operated under the company’s ‘Focus for 150’ programme, which focuses on the period around calving.

On the day, four key pillars surrounding the dry period were discussed. These were: management; minerals; body condition score; and nutrition.

Speaking at the event, Alltech’s Richard Dudgeon explained the importance of minerals in the dry-cow diet.

“The importance of the dry-cow period is to build up the reserve of minerals in cows because – once she calves – a lot of the problems happen in the first couple of days post calving. So, she needs the right amount of nutrients so she can cope with those challenges.

Alltech’s Richard Dudgeon

“So, if we elevate the immunity of those cows, they are better able to cope with the challenges during the dry-cow period and post calving,” he added.

Minerals are divided into two main areas – major minerals and trace minerals.

Major minerals:
  • Magnesium (Mg);
  • Calcium (Ca);
  • Phosphorus (P);
  • Sodium (Na);
  • Potassium (K).

Richard focused on three of the most important minerals during the dry period – Mg, K and Ca.

“Mg is important to prevent challenges such as milk fever. And, the levels we’re targeting are 30g/cow/day or – if you’re feeding a bagged mineral – you’re looking at 20-25% of Mg in the bag; that means a cow will be getting 30g/day.

“Another mineral we need to look at is K. In an Irish sense, we’re feeding silage during the dry period. So generally, what we see in grass silage are higher levels of K and that’s related to the slurry and fertilisers that are applied.

“But, K itself is actually antagonistic to Mg; that’s a negative – that’s something we don’t want to see. So, that’s something that we have to manage,” he explained.

“Generally, when you analyse your dry dairy cow forage and it shows over 2.4% for K, those cows are going to be more at risk to milk fever; so it’s important to balance that and get enough Mg in to overcome that issue as well.”

Richard highlighted that Ca is not needed and the reason for that being that the cow needs to be trained to immobilise her own Ca reserves.

Key trace minerals:
  • Copper (Cu);
  • Zinc (Zn);
  • Selenium (Se).

Richard also outlined some of the important trace minerals during the dry period. He said: “I’ve highlighted these three minerals because Irish forages are particularly low in these.

“These are all important trace minerals in terms of improving cow health and immunity. If you’re having a problem with retained cleanings for example, Se would be one of the key elements that we are looking at in your dry cow mineral.

“The message I’m trying to put across on the dry cow period is, if your having challenges and issues on your own farm, one of the first things you need to do is look at the forage you are feeding and look at the mineral content of those forages.

“It doesn’t cost a lot of money to take a mineral sample; it’s probably in the region of €50-60 for a trace element sample of your forage – that’s the first place to start.

“With that information, it can be assessed as to what levels there are and what the best action to go along with is,” he concluded.