Milking the system: cooler cows keep it flowing

University of Queensland researchers have demonstrated how dairy cows can be kept cool 24/7, helping to prevent heat stress, adding to the cows’ welfare, and increasing milk production.

With hot weather often impacting dairy cattle health, wellbeing, and overall milk production, dairy producers will use a variety of cooling strategies to prevent heat stress in their herds. These strategies include shade, fans, sprinklers, or a combination of all of these measures, and there is a trend towards these being run 24 hours per day rather than simply during the hottest periods.

In a recent study published in the Journal of Dairy Science, researchers demonstrated how extending the strategies 24/7 could lead to better milk production. The researchers showed how these approaches could also be applied to outdoor herds.

University of Queensland lead investigator Dr John B Gaughan, from the School of Agriculture and Food Sustainability, says scientists know that dairy cows should be able to dissipate body heat better at night when the ambient temperature is lower. Beef feedlot studies have also suggested that the cooler nighttime temperatures are critical for the animals to cope with periods of heat stress.

But previous studies on cooling strategies for dairy cows focused on those housed indoors in barns or feedlots, Dr Gaughan says, with few studies looking at pasture-based or feed pad-managed feeding (a confined yarded area, allowing for regular feeding of the whole herd).

Dr Gaughan and his team set out to fill this gap. Focusing on 120 postpartum Holstein-Friesian cows housed on a feed pad, the researchers investigated the impacts of adding nighttime cooling in addition to daytime cooling on the milk yield, rumen temperature, and wellbeing of an outdoor herd exposed to high summer temperatures.

The herd was split into two groups of 60 cows and given two separate cooling treatments over a period of 106 days. The daytime cooling group was cooled with overhead sprinklers and fans while in the dairy holding yard, with ducted air blowing onto cows during milking, shade and fans at the feed pad, and a shaded loafing area. The enhanced day-plus-night cooling group received the same treatment plus thorough wetting via a shower arrangement as they exited the dairy, as well as ducted fan-forced air blowing onto them at night.

“This study is, to our knowledge, the first to investigate the potential of using ducted air as a means of cooling cows in an open pen environment overnight,” Dr Gaughan says.

The team monitored rumen temperatures using a radio-transmitting bolus at 10-minute intervals throughout the study, along with cow activity, panting score, dry matter intake, and overall milk yield. According to the team’s findings, cows in the enhanced cooling group produced more milk and had lower rumen temperatures and panting scores compared with the cows receiving just daytime cooling. Throughout the study, the enhanced cooling group cows also spent more time lying down than the daytime cooling cows, Dr Gaughan says.

“The combination of the shower array and the ducted air systems had a beneficial effect on milk production and cow welfare, and … is a cost-effective strategy for producers to consider [when managing] outdoor herds on a feed pad.”

The ducted system used in the study cost approximately $31,500 but produced $21,308 of additional milk income, meaning that 67.7 per cent of the installation cost was recovered over the first summer, says Dr Gaughan.

“Over time, this kind of enhanced day-plus-night cooling system could provide powerful benefits for outdoor herds, from increased production and profits to boosted cow wellbeing.”

Story source: Journal of Dairy Science.

Photo by Zoe Askew on Unsplash

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