Trace elements

What are trace elements?

Minerals are split into two groups. Macro minerals such as calcium, phosphorus, magnesium, sodium and potassium are needed by the cow in grams per day. Trace elements are needed only in milligrams. Despite the small amounts, the cow cannot do without them, because they are building blocks of many enzymes and hormones.

The main trace elements and what they do

• Copper: immunity, fertility, coat colour and connective tissue. A deficiency often shows as a pale, rough coat, especially around the eyes.
• Zinc: skin, hoof horn, teat skin and wound healing. It is needed to form keratin.
• Manganese: fertility, bones and cartilage. A deficiency is linked to silent heats.
• Selenium: together with vitamin E, protects cells from oxidative stress. A deficiency weakens the defences in the udder, makes retained placenta more likely and causes muscle weakness in calves.
• Cobalt: turned into vitamin B12 by the rumen microbes. The cow needs vitamin B12 to get energy from propionic acid.
• Iodine: building block of the thyroid hormones, which control metabolism and fertility. A deficiency can lead to weak calves.

Why does a deficiency develop?

The content in forage varies widely with soil, fertilisation, cutting date and weather. Many soils in the Netherlands and Germany are low in selenium. Grazed grass often contains too little selenium, copper, zinc, cobalt and iodine. When concentrate is dropped at grazing, its mineral content goes too. You can read more in Grazing: keep a close eye on minerals.

Trace elements also affect each other. Molybdenum, sulphur and iron bind copper, so the cow absorbs less of it, even though the ration contains enough on paper. Organically bound trace elements, such as chelates, are partly absorbed better than inorganic salts.

Dry period and calf

Supply is often underestimated in the dry period in particular. Dry cows are often given leftover feed or lower quality forage. During this time the calf grows fastest and builds up reserves through the placenta, for example in the liver. The cow’s supply also affects colostrum quality. You can read more in Better calves through optimal nutrition in the dry period.

How do you spot a deficiency?

A trace element deficiency rarely shows as a single symptom. Typical are signs in several animals in a group:

• calves with slow growth, weak immunity and coat problems
• heifers with weak heats and many repeat breeders
• more retained placentas and weak calves after calving
• more mastitis and foot problems

If several groups of animals stand out, a blood test on a few animals is worthwhile. For copper, the liver gives a more accurate picture, as blood often shows a deficiency only late.

How can you secure the supply?

• Mineral feed in the TMR: an even supply, provided the ration is well mixed.
• Lick buckets and lick blocks: simple, but intake varies widely between animals.
• Bolus: releases trace elements evenly over weeks or months and makes sure every single animal gets them, also at grazing or in the dry period.

Too much is harmful as well. Selenium and copper are toxic in high amounts, and sheep are especially sensitive to copper. Add up all sources before you supplement any further.

Frequently asked questions

All terms in the glossary