Are your cows eating stones? Here’s why!

Posted on 24 Jun 2021
Are your cows eating stones? Here’s why!

In recent months, reports of cows eating strange objects have started to crop up. Items being ingested include things like stones and plastic pipes. This unusual grazing behaviour is known as pica. 

The dangers of pica in cattle

When ingested, foreign objects such as stones and pieces of plastic can cause gut damage and blockages. If this behaviour continues for a while and is left untreated, the animal may experience serious health problems or even death. 

There is little definitive research on pica, however the three most common causes are believed to be:

Phosphorous deficiency

Studies have shown that during peak grass growing months, phosphorous concentrations in grazing grass can be lower than the levels required by milking cows. A phosphorous deficiency can be diagnosed by a straightforward blood test taken from animals displaying the signs of pica. 

Sodium deficiency

Using fertilisers that are high in potassium (for example, slurry) on grazing ground can sometimes affect the sodium to potassium radio. Pastures are also commonly low in sodium during the early summer months, so unsupplemented animals may be at risk of deficiency. A blood test may help to diagnose low sodium levels in milking cows. Also, a forage mineral analysis of grazing grass can give an indication of sodium levels. 

Lack of structural fibre in the diet

Rapidly growing spring and early summer grass may contain low levels of fibre compared to older grass. When cows don’t have enough fibre in their diet, it can lead to acidosis, loose faeces and a drop in butterfat levels in the milk. If butterfat levels are normal for the time of year, this is an indicator that the pica symptoms are more likely being caused by a mineral deficiency. 

Why is this happening now?

Some believe the recent surge in pica may have been caused by the exceptionally wet winter (when nutrients were leached from the soils) combined with a very dry spring, which may have resulted in a lower mineral supply to grazing cattle. 

What to do if your cows display signs of pica

If you’re worried that your cows are exhibiting symptoms of pica, please speak to your vet. Supplementing with blocks or licks may limit or eliminate the behaviour. In other cases, providing your cows with a source of long fibre (for example, a bale of straw or stemmy silage/haylage) may help. 


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