February Production Drop and Heat Stress
/For many of our clients (especially those more inland), late January/February saw some significant drops in production. Many farms reported cows being listless and inappetant, despite them going into some good quality feed.
I don’t have to labour the point that this summer has been hot (and humid on many days). For a period there was little reprieve as night temperatures failed to dip below 20 degrees. Friesian cows are comfortable in temperatures less than 20 degrees (Jerseys less than 24 degrees). Above these temperatures cows must work to keep their body temperature under 39.0 degrees.
Cows are essentially a large fermentation tank on legs. The rumen produces a lot of heat. This is great in the winter but in higher summer temperatures it means they will struggle to keep their body temperature low. Night time should provide some reprieve if a cow over-heats during the day, but when temperatures stay high throughout the night they may be starting the new day already in heat stress.
Cows in heat stress will open mouth breath (pant), seek shade and spend more time standing to try to reduce body temperature. Think back to when we had bountiful shelter belts as to where the cows would have been standing on these hot days. Once the body temperature raises above 39.5, cows will be less inclined to eat, will have poor immune function and production and body condition may drop.
We cannot replace tree shelter quickly where it has been lost, but other shorter term strategies may be used.
• Cool drinking water is hugely important. Install multiple water troughs in main lanes to and from the shed.
• Wet down the hot concrete before the cows come on the yard.
• Install sprinklers on the yard (these might be used morning and afternoon if the night was hot).
• Put sprinklers on the shed roof (and/or misters inside the shed).
• Try to avoid milking in the heatof the day.
• Milk smaller herd sizes to minimise the time spent on the yard.
• Let cows move at their own pace – chasing slow cows down the lane will just heat them up more.