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Orchard fan results revealed

17 September 2019

Research into the effect orchard fans to reduce heat load in Australian feedlot cattle has found there were no animal wellbeing, productivity or financial benefits resulting from fan usage.

Excessive heat load in feedlot cattle occurs when heat gain exceeds the ability of animals to lose heat through thermoregulation.

Project leader Associate Professor Gaughan from the University of Queensland said with air flow a key driver in heat loss from cattle, the project provided a valuable insight into the effectiveness of using orchard fans to help the process.

“Orchard fans are commonly used in southern Australia to prevent frosts. Technologies to alter wind speed have not been implemented into beef cattle feedlots, so we set out to trial the fans in a feedlot to improve air flow, in particular wind speed,” Associate Professor Gaughan said.

Fans or no fans?

The study involved a randomised complete block study from mid-January 2019 until mid-April 2019 at a commercial feedlot in south-east Queensland, comprising 1,314 animals.

There were two treatments – fans or no fans – and four un-shaded pens per treatment.

Fans were turned on at 6pm on any day where the heat load index was greater than or equal to 93 units at 12pm on that day. Once turned on, the fans then ran continuously until 6am the next day.

Data was collected for each animal including dry matter intake, panting score and carcase traits. Weather data was collected at 10-minute intervals from four onsite weather stations, and air flow across the pens was also measured.

What did the results show?

Associate Professor Gaughan said there were a few major heat events during the study, however, the use of fans did not improve DMI relative to no fans, did not reduce panting scores or lead to any significant differences in carcase traits apart from minor differences in carcase pH and rib fat.

“Based on the findings from this study, it’s unlikely that orchard fans will be of economic value in ameliorating heat load in un-shaded feedlot cattle with 25% to 75% Bos indicus content,” Associate Professor Gaughan said.

“The cost of using the fans was $69.40 per animal (fans treatment) or $0.95 per day per animal, and as there were no objective animal welfare or production benefits it is unlikely that the fans would be a financially viable option.

“What it also demonstrated is that amelioration of heat load by other strategies which many lot feeders are already using, such as the use of shades, pen cleaning and nutritional management are currently better alternatives.”