Earlier this week I received this video from one of our more Southern monitor farms. The main milking herd of 200 cows is housed in two sheds that share a common loafing area between them. Every lunchtime all the cows move out of one shed and all huddle and stand in the other. The empty shed is a little more enclosed by other buildings and an earth bank and has slightly lower roof height. In the evening they are spread between the two sheds and eating and resting as normal.
Midday temperatures in the shed over the past week have been 20 – 22’C to give a short term THI (3 hours) around 68-65. By the evening the temperature and THI have started to drop but only by a few points.
Standing times around lunchtime will be been increased and feeding opportunities/intakes will be reduced. Neither are good for the cow and combined with changes in her physiology (panting, etc) can reduce milk yields.