Using more fertiliser to maximise grass production is causing increasing trace element problems in spring-calving herds, says Mark Pass from Cheshire firm Beeston Animal Health.
Several years of relatively high rainfall have compounded the problem and means it is vital for milk producers to blood-test their herds in order to maintain fertility levels and maximise production, he says.
“Incidences of trace element problems have definitely been on the rise in recent years,” says Mr Pass, who adds spring-calving herds are most vulnerable.
Symptoms of trace element deficiencies in cows
- Copper deficiency can cause poor youngstock growth rates and discolouration of the coat
- Fertility issues and weak or stillborn calves can be linked to a shortage of selenium
- Iodine deficiency leads to thyroid enlargement (goitre). Calves born to iodine-deficient dams may be stillborn or weak and unwilling to suck. It also leads to poor growth rates, low milk production and retained placentas.
“We would have seen about 25% of our customers’ herds calving in spring 10 years ago, but now it is more like 50%.”
Mr Pass says the increased use of fertilisers in these systems is antagonistic to trace elements and causes vital minerals to be locked up.
The growing use of sulphur-based fertiliser is a particular problem, as sulphur can make selenium and iodine unavailable to the animal.
“All trace elements are water-soluble, so the recent high levels of rainfall are a real concern, too.”
Liz Brown from trace-element specialist Agrimin says the reduced use of compound feeds in spring-calving herds is adding to the problem because the minerals and vitamins they contain are no longer available to the animals.
Mr Pass says more milk producers must now add regular blood testing to their routine management.
“I would say only 25% of dairy farmers carry out regular blood tests. However, trace-element availability changes constantly from season to season and from year to year, so it has to be actively managed on an ongoing basis and not just left to chance.”
Ms Brown says controlled erosion boluses are the most effective solution for dairy producers.
“You have to build blood trace-element levels up and maintain them. The most reliable way to do this is by using a high-specification bolus, which releases measured amounts of key nutrients into the bloodstream.”