Keep your cool - managing heat stress in cows

Dairy cows are one of the most susceptible livestock species to heat stress, feeling the effects of increased temperatures as low as 23°C.  This means that for many dairy regions, once in the height of summer, cows can experience prolonged and severe periods of heat stress, negatively impacting on milk production and overall farm profit.

The negative impacts of hot weather reach further than just milk output, with indirect effects on fertility and the general health and welfare of the animal.

The key to managing heat stress on-farm involves a combination of strategies. Environmental modifications such as providing shade, fans, sprinklers, and cool drinking water for cows are highly effective.  However, for areas where short sharp heat events occur the cost of this infrastructure to manage external heat can sometimes outweigh the benefits.

In addition to managing the environment and manipulating genetic selections, the DairyFeedbase Feeding Cool Cows research team has been investigating nutritional strategies that have the potential to minimise the negative impacts of hot weather.  Research has included examining the impact of heat on temperate forage production and nutritive characteristics as well as the effect of different feeds to reduce heat impacts on cows.

Senior Research Scientist Dr Leah Marett said research in the DairyFeedbase Cool Cows program showed that the nutritional quality of a range of temperate forages is impacted with higher temperatures.

“Results showed that when temperatures exceeded 25°C, the fibre concentration of the plants increased while the concentration of soluble carbohydrates decreased. This reduces the quality of the feed grazed by cows during hot weather, resulting in likely flow-on effects on milk yield.”

During the project, the team investigated a range of nutritional strategies that had the potential to reduce cow body temperature during times of hot weather.

Betaine, a naturally occurring supplement derived from sugar beet, has been the focus of several previous research efforts and has been shown to improve production responses in several livestock species during periods of heat stress. In this research, Betaine proved to mitigate the rise in cow body temperature during a heat event, while also aiding the cow to maintain feed intake and milk production. Economic analyses of research data showed that under most situations it can be economically viable to feed Betaine to a dairy cow during the summer period.

The research team also examined the role of fats, oils and lower fibre forages on cows in managing periods of heat stress with fats and oils proving effective only in some situations.  However lower fibre forages, such as chicory, were highly effective in minimising body temperature accumulation during a heat event, enabling cows to better maintain milk production during times of heat stress.

Further research is occurring at a herd scale across Australia to examine the impact of genetics and the environment on milk production.

Find out more about Feeding Cool Cows to help enhance your farm business.