Heat stress can cause major issues in your herd. Dairy cattle, being a European animal, are not made for the Waikato heat and humidity. It has been proven that they show signs of heat stress at temperatures as low as 23 degrees, which is exceeded almost every day through summer.
Heat stress can lead to a drop in milk production, early loss of pregnancy, and in extreme cases death. Signs to look out for in your herd are a production drop, panting, irritability, shade seeking, and clustering of cows (to try and get in other cows’ shadows). A good tool to determine the risk of heat stress is to use the ‘Temperature Humidity Index’ pictured below, which gives a risk based on the relative humidity and temperature.
There are several ways you can help reduce the impact of heat stress including:
Installing sprinklers in the milking yard
Ensuring the milking yard isn’t stocked too densely
Splitting the herd so that limited time is spent at the cowshed
Moving milking to early morning or late afternoon
Ideally having multiple troughs and shade in each paddock, as well as a trough in the race if necessary
Despite these options, if it is a 30-degree day with 80% humidity, there is little you can do to avoid some level of heat stress, especially if you are still on twice a day with the improved payout. We are currently stocking Propath LQ Zn, which is a more bioavailable form of Zinc than that used to prevent facial eczema.
Zinc actually plays an important role in immune function and cell health and feeding it in this form can increase antibody production and antioxidants, thereby minimising potential health problems (such as those secondary to heat stress). At the recommended dose (2-4g/cow/day), treatment dose is 6 cents per cow.
Studies have repeatably shown cows on Propath LQ Zn have
· decreased SCC
· decreased severity of clinical mastitis
· improved milk production
· improved feed conversion efficiency
· decreased lame cows
· improve keratin plug formation at dry off
When you’re thinking it’s way too hot outside, just keep in mind that you are not the one standing in the sun with a black leather jacket on!
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