Mineral nutrition: Getting it right this dry cow period

By Eddie Phelan, regional manager, southwest, Alltech Ireland

AgriLand has teamed up with Alltech to bring to you the Alltech dry cow action plan – an informative, eight-week series of articles to help you make the best decisions this dry cow period and take steps to ensuring a trouble-free spring and profitable lactation period in 2020.

Feeding a dry cow mineral throughout the dry period (ideally six–eight weeks) is essential. This builds up a good reserve of minerals, allowing the cow to calve down without any issues and continue into the lactation to follow.

Most Irish silages lack the required mineral levels to get the cow through the dry period. If you have not already done so, test your silage for minerals. This will show you what mineral supplements are needed.

Macro minerals

Magnesium (Mg) aids the cow’s metabolism and absorption of calcium around calving. Throughout the dry period, a cow needs 40g+ Mg/day. If analysis shows 0.15% Mg, a cow eating 11kg dry matter (DM) during the dry period will take in 1.65g/Mg from silage.

As a result, at least 30g of Mg supplement will be needed. If the feed rate is 120g/head/day, at least 25% Mg is needed to make up the deficit.

Potassium (K) in Irish silages is typically between 1.8–2.4%. However, dry cows only require 0.52%. K interacts with Mg, tying it up in the rumen.

This slows down the absorption and mobilisation of calcium (Ca), leading to milk fever. Sufficient Mg supplementation helps to manage K levels.

If K is over 1.8% in silage, alternative measures should be taken, such as reducing the level of silage included in the dry cow diet and/or introducing Cal-Mag or sweetened Cal-Mag.

Milk fever

Research shows that where milk fever is well controlled, approximately 33% of cows may experience sub-clinical milk fever.

Customers often ask me: I had a higher number of cows go down with milk fever before calving, despite using boluses. How can I reduce the risk of this happening again?

  • Test silage for Mg and K and supplement accordingly;
  • Check the Ca level in the dry cow diet. If over 0.45% of total dry matter intake (DMI) (~50g), the cow will become too dependent on the supplemented Ca. This may lead to problems mobilising Ca from her bones, leading to milk fever;
  • Monitoring and controlling cow body condition score (BCS) in late lactation and throughout the dry period reduces milk fever risk. Cows should be dried off between BCS 3–3.25 and this BCS maintained throughout the dry period. A too high or too low BCS may increase milk fever risk.

Pat Brennan, a farmer from Ballyouskill, Co. Laois, has seen huge improvements since including Bioplex and Sel-Plex minerals from Alltech in his dry cow minerals.

He previously had issues with milk fever. Now, Pat has reduced his milk fever incidence rates to less than 2%. The fertility levels in his herd are exceptionally high, with a submission rate of 90% in three weeks and 90% of the herd calving within six weeks. His calving interval is 366 days and his somatic cell count (SCC) is 90,000.

Trace minerals

Trace minerals, or micro minerals, are vital to the overall immunity, fertility and production of dairy cows.

Irish grass silages have shown to be 63% low in copper (Cu), 69% low in selenium (Se) and 29% low in zinc (Zn) (Rogers and Murphy, 2000), making supplementation essential.

Important trace minerals include:

  • Zn supplementation is important throughout the year. It helps to control SCC, reduce incidences of mastitis and maintain hoof hardness;
  • Se is a natural antioxidant that supports calves’ and dairy cows’ immune defence. Se supplements are only effective if fed with the correct levels of vitamin E, as the two work in synergy. This is very important regarding maize and silage diets, where vitamin E is low;
  • Cu plays an important role in fertility and immunity. Cu deficiency can cause many issues, such as poor growth, reproduction problems, impaired immunity and diarrhoea.

Customers also often ask about the level of held cleanings. When this level increases, the mineral supplementation level can also increase. This is not always beneficial.

See below some key points on the issue:

  • As always, test your forage for minerals and supplement for Mg and K accordingly;
  • Then, check the label to see what type of mineral you were feeding; ask your supplier if you are not sure. If most of the elements are inorganic (i.e. zinc oxide), mineral interactions can occur, such as the zinc oxide interacting with Cu, making it less available for absorption, which may lead to more cows with retained placentas;
  • Choose a dry cow mineral that goes to work, not to waste. Organic minerals such as Bioplex Cu, manganese (Mn), Zn and Sel-Plex (organic Se). These are proven to mimic the minerals found in the grass and are, therefore, more bioavailable, with better absorption and less chance of mineral interactions.

Research has shown that feeding trace minerals in their organic form leads to better absorption, storage and utilisation by the cow. This helps build the cow’s immune system and lowers the risk factors associated with difficult calvings and retained placentas.

Feeding Bioplex and Sel-plex minerals has also shown to reduce age at calving for first-lactation heifers by 26 days, whose dams were fed these minerals during the dry cow period compared to dams fed a control (Figure 1).

Figure 1

Using proven technologies as part of a dry cow nutrition programme generates greater return on investment, benefitting both cow performance and farm profitability. Many farmers across Ireland are now seeing a positive response in their herds from using Bioplex and Sel-Plex in their dry cow mineral.

To find out more

AgriLand has teamed up with Alltech to bring to you the Alltech dry cow action plan – an informative, eight-week series of articles to help you make the best decisions this dry cow period and take steps to ensuring a trouble-free spring and profitable lactation period in 2020.

Part 1: The importance of a successful dry cow programme

For more information on Bioplex and Sel-Plex minerals, call Alltech on: 059-910-1320 to get in touch with an Alltech representative; or click here