Minerals: you can't improve what you don't measure!

This season presented some abnormal trace element results, even on high-producing farms.

Our advice is to check the mineral status of your herd before mating, to which the common response is often "but I haven’t changed anything", or, "our results have always been ok". 

Unfortunately, each season is different and, therefore, results can be different. This season was very abnormal!

We took liver and blood samples from different farms and the milk production varied from 300 to >500MS/cow. The results showed: 

  • 38% of farms had a deficiency in copper;

  • 31% had a problem with low magnesium;

  • 15% had an issue with high magnesium levels;

  • 23% had selenium deficiency.

And yes, even the high producing farms had issues!

Copper deficiency

Copper deficiency can be a primary deficiency (a shortage of copper itself), or a secondary deficiency (i.e. because of an overload of copper antagonists).

Copper does not get well absorbed when there is too much molybdenum and sulphur around. Absorption is also negatively affected with high iron, high manganese or even high zinc levels.

On one of our farms with low copper in the herd, we know that molybdenum is the cause of all issues. As the molybdenum or sulphur applications can change year by year, copper levels need to be monitored annually.

As each litre of milk contains a standard amount of copper, it is very easy to see that a deficiency will lead to lower milk production. On top of this, there are more consequences for younger animals, especially yearlings and first- and second calvers.

This year, we found yearlings with low copper levels in their liver. Low copper levels in animals that are still growing themselves AND have to grow a calf can lead to huge problems, especially when they are put on a brassica crop over winter, or on diets with low protein. 

As copper is required for bone growth, the above combination of events can easily lead to cases of fractured legs in first calving heifers in spring!

We therefore advise you to check the copper levels of R2’s before problems arise (e.g. in April/May).

Magnesium deficiency

Magnesium deficiency can cause grass staggers, but a secondary issue can be milk fever, as magnesium and calcium are absorbed into cells through the same transport system. 

Magnesium is not stored in the body, so the level in the blood is an indication of intake in the last 24-48 hours.

Marginal levels around mating can cause issues. Cycling cows move more and are generally active. If cows with marginal levels cycle, there is a higher possibility of them going down with grass staggers or even milk fever.

Too much magnesium

Too much magnesium can be simply a higher daily intake for that individual cow, or too much supplementation in general. We often ask more questions to help make a distinction between the two. 

High magnesium levels in cows that have calved are often not problematic, as they will pee the extra magnesium out very easily. However, high magnesium levels pre-calving can cause a huge amount of down cows around calving. 

If you have more than 2% of cows down over calving, please ring the clinic to get some bloods taken to see if too much, or not enough, magnesium is the issue!

Selenium deficiency

Selenium deficiency was present in almost a quarter of our farms this year. Besides being required for immunity, selenium is also important for fertility and growth. 

A lack of sufficient selenium can lead to

  • high somatic cell counts;

  • more mastitis/having to treat cows for longer;

  • calf scours (because of worms, corona, coccidiosis etc) for longer;

  • more sick calves in general.

Cows with low levels of selenium can have a normal submission rate, but the conception rate will be reduced. Unfortunately, you will only find that out at pregnancy testing time, which is too late to change anything. 

Check your levels so you can be proactive instead of reactive by culling empty cows!

Top up your calves at weaning

Weaning is a stressful time for calves. Supplying them with trace elements at this time can set them up for months! 

Every year we see calves getting weaned at 90-100kg, but then a month or so later, they have not put on much weight at all. Calves can easily grow 800g - 1kg/day, which means that if you wean your calves before Christmas at 90kg, they should be at least 120kg at the end of January/beginning of February!

Test, test, test!

In summary, to ensure you get the best out of your herd, we recommend 

  • taking blood and liver samples to test for selenium, magnesium and copper levels;

  • checking pregnant yearlings' (R2's) copper levels around April, if you are going to feed them a brasssica crop, or another low protein diet, over winter. 

If you are not happy with your production or reproduction results, please come and talk to us.

Remember, you can’t improve what you don’t measure!!