The current, prolonged heat wave is creating a number of challenges across our region. There is concern over forage stocks and grazing, where fields are desperate for some rain to make them grow.

It is the dairy cow herself, though, that is struggling the most when it warms up. In fact, a temperature of just twenty-two Celsius is enough to cause the animal stress.

Humidity, too, should also be a consideration. As I write this it is twenty-five degrees, cloudy and fifty-eight percent humidity.

This would cause a cow mild-moderate stress – breathing increases to seventy-five breaths per minute, body temperature exceeds thirty -nine degrees, milk yield and milk fat will decrease and the cow will be more lethargic.

Lethargy is the cause of many issues linked to heat stress. As the temperatures rise during the day cows are less likely to want to eat and dry matter intake suffers.

It may be tempting to increase the energy density of the diet by adjusting the forage/concentrate ratio. However, one stills needs to maintain structural fibre in the ration to avoid ruminal acidosis.

The very best forage should be made available at this time and, if feeding indoors, split the diet into two smaller feeds.

Recently, I witnessed cows sorting through the diet when they hadn’t in the past. They were searching for the best bits of the diet - the energy dense blend – and then going for a lie down. Acidosis soon followed. The farmer and I solved the problem by adding water to the mixer wagon at a rate of five kilos per cow.

This made the ration bind together better to prevent the sorting, and the cows needed the extra water anyway!

Heat stress is a costly burden that we should be proactive in addressing. Provide shade, where possible. If cows are kept indoors it is worth investing in fans.