NEW research has found UK soils - like most across the EU - to be selenium deficient.

Trials conducted across the UK and Ireland this year showed the guideline selenium content was consistently not met in grass and forage production - many control groups contained less than half the recommended level of 0.1ppm of selenium (Se).

Fertilizer company Yara UK, conducted the trials and found that when fertilizer with added Se was applied, it consistently rose to above the guideline level.

It is well-known that dairy cows with Se deficiencies are likely to suffer more from mastitis and lower fertility. However, it is less known that it can also cause white muscle disease; higher cell counts; unthriftiness, growth depression and diarrhoea; retained placenta, cystic ovarian disease and anaemia.

Jez Wardman, Yara agronomist, said: "Based on the Se deficiencies seen across all the trials we conducted, it is essential to consider the level of all nutrients readily available in forage, in particular Se, as most herds will not be gaining the Se concentrations required from forage alone."

At the Grasstech event near Elgin eight trial plots were set up on various seed mixes including two, three and five year silage mixes; two multipurpose mixes; two long term grazing mixes; and a red clover mix.

All showed a significant increase in Se availability after fertilization with added Se, with long term grazing mixes and red clover showing the greatest benefit, up from 0.06ppm and 0.14ppm respectively to 1.16ppm and 1.17ppm.

Mr Wardman said: "There are various ways in which you can add Se to the diet. Either by increasing the concentration in food through feed supplementation, increasing the concentration in forage through fertilizer supplementation or a combination of both.”

Mr Wardman said some farms would need to reconsider the way they approach adding Se to the diet. “Some options from inorganic sources do not allow efficient transfer of Se and thus the content in the blood remains below critical levels.

“Grass takes up Se during its normal growth pattern and incorporates it into its proteins. This is an important aspect as in this form the Se is more available than when in the inorganic salt forms associated with mineral licks and supplements.”

In addition to the trials, samples were also collected from ten leading farms involved in the Yara Grass Prix competition; a competition run throughout 2014 to reach the highest energy yield (ME per hectare) across two cuts of silage.

Each out performed the national average for fresh weight, ME and DM value however analysis showed the average Se level across first and second cut silages was only 0.04ppm significantly below recommended levels.

“Analysis of soil is recommended as deficiencies can vary on a field by field basis, this will allow decisions to be made based on all macro and micro nutrient availability that can impact upon animal health and production,” said Mr Wardman.