With the on-going poor weather one is tempted to forget about heat stress! However, now we are in the peak of the summer season, the underlying temperatures are all much warmer than earlier in the year. Any slight rise in temperature or a sunny afternoon is enough to push the cows up into heat stress. We saw this towards the end of last week. Grazing conditions have been much more variable than in the housing; at this time of year a sunny afternoon can heat up any cows that are not in the shade and increase the potential for milk yield losses. If the cows cannot get out of the sun fertility can be impacted and standing times will be increased (which can lead to lameness problems in 8 – 10 weeks due to solar-ulcers). Predicted maximal weekly average milk yield losses are more variable ranging from 0.5 to 3.1 liters a day all depending on how much direct sunshine the farm gets.
This week’s weather forecast is for the rain to clear and then a high pressure system will generate several hot days later in the week and it will remain hot and humid into the weekend.