Renovating dams and improving water quality could fatten up cattle and reap long-term financial rewards, according to a new study by the Australian National University (ANU).
Aussie researchers, led by Leo Dobes, conducted a cost-benefit analysis of renovating dams to promote weight gain for cattle on farms in south-eastern Australia. They found that there was a strong likelihood that per-farm financial benefits would outweigh the costs of renovating, with an increase of 1.5 times for NSW and up to 3 times for Victoria.
“The key finding is that beef cattle are likely to gain more weight if they have access to better water quality than that available in many turbid Australian dams that are infused with faecal and other organic matter,” says Dobes.
According to the analysis, that would equate to yields of around $85m for the farms in NSW, and $519m for Victoria in prices derived from 2019.
The authors also note that renovating dams could improve sustainability by preserving biodiversity and reducing carbon emissions.
Without much data on Australian farms, the team analysed data from multiple cattle ranches in the US to see whether cows were likely to gain weight when they had access to higher quality water from renovated dams. They then compared the weight gain to present day Australian prices of meat per kilogram to determine yield.
They also calculated the cost of renovating the dams and found that, for every dollar spent, $1.5-$3 could be reaped from the resultant heavier cattle, as long as the cattle were gaining at least 1.8%-6.5% of their body weight annually, depending on location and rainfall.
However, they calculated that there was around a 70% chance the per-farm benefits would, indeed, justify costs.
“The experiments on which weight gain was assessed in this study generally compared ‘clean’ water from wells, rivers, or fenced dams that denied entry to cattle, with ‘dirty’ water where cattle could enter and stand in an unfenced dam,” says Dobes.
“One question that bears further investigation is whether cattle will drink as much ‘dirty’ water as ‘clean’ water. North American observations are inconclusive, and authors have warned against [human] bias in thinking that cattle prefer water that appears potable to humans.
Some of the ways to improve the dams could include permanent fencing, adding dense grass areas, making sure trees were in areas that didn’t interrupt spill ways, and providing shallow areas for wildlife to live in.
“Fencing off dams has been shown to reduce levels of E. Coli and other thermotolerant coliforms, as well as lowering levels of turbidity, nitrogen and phosphorus, while promoting native macroinvertebrate species,” says Dobes.
“So another unanswered question is ‘why have Australian farmers persisted for so long in generally not provided cattle with ‘clean’ water by fencing off dams, if it results in greater weight gain?’. After all, farmers seek to increase productivity through improved pasture, genetic manipulation, and other costly strategies.”
In their paper, published in PLOS ONE, the authors also note there is variation between farms, regions and US climate conditions, so they encourage further studies that focus on weight gain under Australian conditions.
Deborah Devis is a science journalist at Cosmos. She has a Bachelor of Liberal Arts and Science (Honours) in biology and philosophy from the University of Sydney, and a PhD in plant molecular genetics from the University of Adelaide.
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