Heat stress & Lameness

Temperatures have been very high over the summer months and people are enjoying their summer holidays with long days at the beach, water skiing and swimming. At home we turn on the air conditioning or have a fan blowing through the night helping us sleep. We enjoy temperatures of around 20-25 degrees, and I am amazed how many people believe that to be the same for cows.

The optimum temperature for a dairy cow is between 5-15 degrees. It does depend on the humidity but when the temperature rises above 15 degrees a cow is starting to feel warm. The reason why this is so much lower than for people is because a cows rumen produces a lot of heat as it is digesting food. As external temperatures rise, it is not unusual to see cows congregating around the water trough – just standing. Somehow this gives them a measure of relief or minimises the effect of the heat on them. It doesn’t take long to find cows panting in the paddock or in the holding yard. When you have the cows in the yard you can often feel the heat radiating off them.

Heat stress has been shown to have a big impact on lameness. The heat itself is stressful but also dehydration that often goes along with it. Dehydration does damage to the soft tissue in the body and this can occur within a few hours. It is important to do whatever we can to minimise the heatstress on our cows. Shelter in the paddocks would be great but often trees give minimal shade for the cows to stand in –  if we have trees that is.  It is hard to supply enough shelter for the cows but there are many other things we can do including: more water troughs in the paddock, on the tracks and by the cow shed. One thought is to seal off the meal troughs in the cowshed and fill them with water if you don’t feed meal anymore. This would help cow flow in the shed and it would provide water for all cows. Even the less dominant ones will have an opportunity to drink as much water as they want without being pushed away. Milk production will also improve when the most important nutrient is properly provided for.

Some other suggestions are: make sure the longer walks are being walked in the cool of the day. It can be tempting to have the cows closer to the shed overnight, so you don’t have to get up quite so early to get them in in the morning but this is not so cow friendly when we have such hot weather.

Having sprinklers on the yard to cool the cows down is very helpful. It needs to be said that it is better to use slightly warmer water as cold water is too much of a shock to the system.

Misters in the cowshed is also helpful alongside fans to suck out all the warm air in order to cool the cow shed down as much as possible. This will also help keep fly population down, which is another considerable stress factor for the cows in the heat.

Undoubtedly, there are other things we can do to make the cow’s environment more cows friendly. It doesn’t have to cost a lot of money either but the benefits to the cow are enormous and therefore the benefits to you as well. I would be interested to hear how you are managing the heat stress in your cows –  info@dhi.ac.nz

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