It seems that warmer weather has finally arrived! Most people seem to be relishing this bit of a heatwave, but how are your cows faring?
A cow is most comfortable at temperatures much lower than we are, with their comfort levels being between -10 and 18 degrees Celsius. The THI (temperature humidity index) shows the interaction between air temperature and humidity and has been well documented as a guideline for where cows start experiencing heat stress, with a level of around 70 being a trigger point. As an example this relates to around 21 degrees C at 70% relative humidity (there’s a great calculator on the DairyNZ website https://www.dairynz.co.nz/animal/cow-health/heat-stress/).
When cows are heat stressed, we see increases in the breathing rate, internal temperature and water intake, as well as decreases in their feed intake, rumination rates and milk production. Milk composition (fat and protein %) often changes before you see a change in the total volume, and we can also see impacts on reproductive performance.
So how can we help mitigate heat stress? There may be some considerations you can make on farm, such as providing adequate water (cows can drink double their normal water intake when heat stressed), look at options for altering milking time or walking distances, offer shade if practical, feed highest quality feed as possible and offer higher fibre supplements at night when it is cooler and consider options for cooling systems at the dairy shed – though do remember that if these aren’t done well that can actually make it more uncomfortable for the cow as you end up raising the humidity around her.
The Allflex Livestock Intelligence system we work with can monitor the heat stress of the animals and herd by measuring their panting/heavy breathing.
Looking at this graph from a NZ farm we can see the level of heat stress occurring through the afternoon, with at points having over 40% of the cows panting at a given time. We can also see the impacts this had on their eating and ruminating behaviour. This herd averaged 108 minutes per cow of heavy breathing, with a drop in rumination of over an hour compared to their normal.
So just remember, that even when you are enjoying the beach weather, your bovine friends may not be.