Dairy Management: pica and low milk urea nitrogen

The prolonged dry spell seems to be coming to an end, according to weather forecasts with thunder showers expected this week followed by low pressure and south westerly weather patterns by the weekend.

It was good while it lasted but most farmers will be glad to get rain as grass and other crops are beginning to show signs of stress.

Grass growth is slowing down significantly on many farms, particularly on light, free-draining soils.

Two other issues are also emerging. One is evidence of pica or phosphorus deficiency in dairy cows. The obvious symptoms of this are cows eating stones, plastic and polywire.

According to companies selling minerals to farmers, there has been a big increase in demand for phosphorus in recent days as more and more herds are showing symptoms.

Additional phosphorus either through the water or through the meal will usually rectify the problem within 10 days or so.

Another issue that is coming up is low milk urea nitrogen (MUN) in the milk tests results. Not all co-ops test for this, but on many farms there are reports of MUN being in the low single digits while the target range is 25 to 35.

Ultimately, there is limited science to say that farmers should be doing anything about these results. There is a school of thought that it indicates that protein intake is depressed, but grass tests I have seen suggest that the protein level in grass is still high.

If protein level in the grass was in the low teens then there would be far more merit to taking action such as increasing protein content in the concentrates.

For now, my advice would be to sit it out and see if the results change over the coming week. Teagasc researchers place little weight in what the MUN tests say provided all other factors are ok, such as milk yield, fat and protein percent, etc.