Using nutrition to keep cows cool in hot weather

The focus of the Feeding Cool Cows project, which is part of the DairyFeedbase program, is to use nutrition to reduce the negative impacts of hot weather on dairy cows. A key part of the project is to determine which nutritional strategies are more profitable to implement and investigate how they can be used in conjunction with other management practices.

At the Agriculture Victoria Ellinbank SmartFarm, a range of feed types have been fed to cows under hot conditions with the resulting feed intake, milk production and body temperature of individual cows measured.

Feeding cows a low fibre forage, such as chicory, improved milk production and the body temperature of cows remained lower during short-term heat events, compared with cows that were fed silage with higher fibre concentration. The long-term implications on profitability are unclear at this stage, but cow production, welfare and fertility are expected to benefit when the rise in body temperature during heat stress is less extreme.

We know that cow factors, including genetics, have a large role in regulating milk production during hot weather. To understand how genetics and nutrition interact during hot weather and influence milk production, the project team are now undertaking herd-scale experiments.

Over the past year, we have started working with partner farmers across Australia to help identify if there are regional differences in milk yield responses to hot weather. This is important because the most appropriate heat stress mitigation measures may differ between regions with different weather characteristics during summer.

Working completely remotely due to COVID-19, the project is capturing daily milk yield data from around 8000 individual cows, in 14 farms across three states, to match with daily weather data. On-cow sensors will be used to identify activity behaviours associated with heat stress, and changes to body temperature.

Data analysis and interpretation from partner farms are still in the early stages, but the project team along with DairyBio colleagues are generating some key insights into the genetic x environment interaction during hot weather and how this influences milk production responses. The Feeding Cool Cows team have developed a dynamic farm systems economic model to understand the net benefits of changes to nutrition, infrastructure and herd structure during hot weather. This model will ensure the work is relevant to commercial farms and the outcomes are profitable.

The DairyFeedbase Feeding Cool Cows project is a joint initiative between Agriculture Victoria, Dairy Australia, and the Gardiner Foundation. For more information visit the Dairy Australia Cool Cows resource page.