The new hot topic – how can you avoid heat stress?

Helen Rogers, Rumenco technical advisor
Helen Rogers, Rumenco technical advisor

Heat stress symptoms can start to become apparent when ambient temperatures rise above 25°C, and with temperatures this week hitting 30°C or more, it’s vital farmers stay alert to at risk cows to avoid costly implications.

Helen Rogers, Rumenco technical advisor, explains dairy cow welfare and productivity will suffer in the heat if changes aren’t made. “Dry matter intake has been estimated to drop as much as 8-12% as temperatures rise, affecting milk production by up to 20%.

“It’s estimated that 1kg of milk is lost for every 0.5kg decrease in dry matter intake.”

A drop in milk production is often a clear sign of heat stress, however, the first sign of moderate heat stress can often be rapid shallow breathing, Helen explains. “Heat stress is likely if respiratory rates are greater than 80 breaths per minute in 70% of the herd.

“Higher producing dairy cows will be more susceptible to heat stress as a result of their higher dry matter intake, resulting in more metabolic heat generated.”

To avoid heat stress causing issues, Helen gives her top management tips. “Provide shade to allow cows to rest in a more comfortable environment. For indoor herds, cooling fans and sprinklers are also effective.

“Water requirement increases significantly as the environmental temperature rises. As water is the primary nutrient needed to make milk, accounting for over 85% of the content of milk, this can have a significant knock-on impact to milk production.

“It may also be beneficial to make changes to the feeding ration, for example including higher quality forages that are digested faster and therefore create less heat. As intakes are affected by the heat, it’s important to get as much from every bite as possible.

“I would suggest incorporating a supplement such as XPLS into cows’ diets, as research has shown that it’s a rich nutrient source for rumen microbes, which helps improve ration palatability and digestibility.

“Optimising the efficiency and functionality of the rumen microbes improves digestibility, even with a lower dry matter intake, which helps cows get the most out of each bite. It’s also proven to promote dry matter intake, bolstering the effect of heat stress. This helps sustain milk production and prevent further health and reproductive complications as a result of this seasonal spike in temperatures.”