A THREE-YEAR pilot project has shown installing shade structures in largely treeless paddocks on the Barkly Tableland can increase calf survival rates.

Led by Senior UQ Research Fellow Dr Kieren McCosker, the project evaluated the animal impact of feedlot-grade shade shelters installed close to watering points in Mitchell grass-downs country on Avon Downs station in the Barkly Tablelands region.

“This region has high humidity, and temperatures above 40 degrees Celsius are not uncommon when cows are calving,” Dr McCosker said.

The average calf loss in this environment was around 17 percent, but it was also not uncommon for this to exceed 30 percent for heifers, he said.

“When an animal is hot, it loses its appetite, resulting in less energy, which we suspect reduces milk supply and maternal support, ultimately affecting production,” Dr McCosker said.

The research team assessed the production benefits of shelters with a 75pc UV-block, installed at watering points in a 56sq km paddock. Temperatures were frequently 10pc lower under the shade than outside.

Previous research like the Cash Cow project demonstrated the increased risk of calf loss during the calving period when high heat loads are experienced.

In the trial, 760 Fullblood Wagyu heifers were monitored via GPS trackers, and weather stations were used to monitor conditions and determine a heat index.

“Our GPS data measured the distance each animal walked and the time spent under the shelter,” Dr McCosker said.

Researchers observed that all animals monitored sought shade at times, but the duration of shade-seeking varied between individual animals and environmental factors.

“Our analysis indicated that cattle could effectively dissipate accumulated heat loads by utilising shade for extended periods,” he said.

“This pilot study observed that mobs with access to shade had a 5.9pc higher calf survival rate, and more highly ranked shade-seeking individuals tended to have fewer calf loss events.”

Dr McCosker said while not statistically significant, the results from the pilot warranted further investigation.

“Given the high rate of average calf loss in northern Australia, an intervention that can reduce this by close to six percent would have a large impact on production,” he said.

“We’re working with industry to see how we can investigate further, because a better industry understanding of calf loss would ensure continuous improvement in animal welfare, which is essential for maintaining consumer and community support for grassfed beef.”

Beef Central asked Dr McCosker whether breed type may have been a factor in the calf survival results.

“It’s a good question,” he said. “Naturally, at the beginning of the study I would have thought so. But Wagyu are indeed very hardy – a lot more hardy than I actually gave them credit for,” he said.

“It’s a hard one to speculate about, but I think if you did go to a really susceptible animal like a British breed, I wouldn’t be surprised if we had seen an even bigger difference. I would have to say there would be a breed effect, but how far that would change things is an unknown at this stage.”

The shade structures at the various watering points in the trial paddock cost around $35,000 each to construct, Beef Central was told.

Cost/benefit

It’s important to note that, although the effect of shade on foetal and calf loss was not found to be statistically significant in the study, a cost-benefit analysis was conducted to determine the level of calf loss mitigation necessary to break even from implementing the intervention.

The base scenario assumptions utilised in the analysis.

• Construction cost per shade structure: $35,000
• Assumed pregnancy rate of cows in the paddock: 100%
• Size of shade structure: 25m x 7.5m = 187m²
• Shade capacity of each shade structure (number of cows): 75. Note: The recommended space requirement per animal in a feedlot setting is suggested to be between 2 – 6 square metres. For the analysis, a 2.5sq m space requirement was employed. This assumption was based on the calculation that the estimated carrying capacity of the trial paddock was 500 cows and equipped with six shade structures. These structures provided a minimum of 1122sq m total, equivalent to 2.2sq m per cow. It should be noted that during the study period, due to poorer years and the paddock not being stocked at full capacity, a total of 9sq m was available per cow if they sought shade simultaneously and distributed themselves equally across each shade shelter.
• Value of weaner: $2500 (Based on the entry value of weaner at the feedlot, weaned at 200 kg)
• Discount rate: 7pc

Based on the above assumptions, a discounted cash flow analysis over ten years was conducted. The Net Present Value (NPV) of the shade treatment was calculated as -$17,441 if 1 additional weaner was produced per 75 cows per year. The break-even point would be two weaners and based on the actual results of approximately an extra four weaners per 75 cows the NPV would be $35,236.

Using a weaner value more representative of a typical Brahman/Brahman cross herd of approximately $800, the NPV of only one additional weaner would be -$29,381 and seven additional weaners would be required to breakeven.

Ian Braithwaite

North Australia Beef Research Council member Dr Ian Braithwaite said he believed the idea behind the research would work with smaller, less expensive shades aimed at calves.

“With the losses that we are seeing, a 5.9 percent improvement in survival rate is a substantial result in terms of the welfare of our cattle,” Dr Braithwaite said.

“Producers would be willing to consider anything to reduce calf losses.”

Led by the University of Queensland, the study was funded by Meat & Livestock Australia and completed in collaboration with the NT Department of Industry, Tourism and Trade and the Australian Agricultural Co.

The full report can be accessed here.

Source: UQ