CALF loss is a major problem for pastoralists in northern Australia, and recent estimates are that it is costing the industry up to $400 million per year.
But how can cows be monitored during calving, particularly when they forage across thousands of kilometres of far-flung bushland?
What exactly can be done to reduce calf loss on pastoral stations?
And how can the cause of death be determined when calf carcases are difficult to find under the extensive conditions?
Those are the questions producers asked and the Northern Territory Government's Department of Primary Industry and Tourism and Trade and Meat & Livestock Australia (MLA) are investigating through the CalfWatch project.
As part of the project, the department's livestock research officer Tim Schatz used GPS-tracking collars and birth sensor systems to monitor about 200 cows over the 2019-2020 calving seasons.
In collaboration with researchers based at the University of Florida, they modified an existing 'barn' system of birthing sensors for use in northern Australia where mobile phone coverage was limited.
Although trials were not held in Western Australia, Mr Schatz said results were still applicable to northern pastoral parts of the State and that remotely monitoring calving might be of use for some stud breeders and those running high value cattle who would like to know when calves are born.
But he said it was mostly a research tool, and that using it to reduce calf loss had the potential to improve incomes, and benefit the wider beef industry.
"In northern Australia it is not uncommon for calf loss to exceed 30 per cent in first calving heifers and 15pc in cows," Mr Schatz said.
"Halving these losses should be achievable and would provide significant benefits."
The CalfWatch project has just been completed, and Mr Schatz is now looking at developing a more reliable GPS collar system with accelerometers that can send calving alerts without the need for birth sensors.
During the three-year trial, birthing sensors were inserted into 200 pregnant cows up to four months before calving and GPS tracking collars recorded their location every 15 minutes in a 2,215 hectare native pasture paddock at Manbulloo station near Katherine, NT.
So, how does the system work?
- Birthing sensors identify when a cow was calving by detecting a rapid change in temperature when they are expelled from the cow.
- A UHF signal is emitted and received by antennas mounted on 12 metre high towers in a low-power wireless-area network.
- From that a calving alert is then sent and is also immediately viewable online.
- Meanwhile, the GPS collars provide the location of cattle in real time on a website maintained by the company that produces the collars, Smart Paddock.
Mr Schatz said expelled birth sensors and newborn calves were much harder to find in northern Australia - where paddocks were larger with more trees and longer grass - compared to the research sites in Florida.
"This reinforced the need for additional ways of finding birth sites and calves, particularly in larger paddocks," he said.
"Putting GPS tracking collars on cows was the solution to that problem."
The birth sensors cost $250 each and have enough battery life to be used two to three times.
A fully-equipped tower cost about $9500 and four towers were required to provide satisfactory coverage of the paddock at Manbulloo.
Over the 2019-2020 calving season, alerts were successfully received from 85pc of birthing sensors and if the collar was working, the department's researchers were able to locate cows for observation.
Mr Schatz said there was some difficulty in finding aborted foetuses before predation, so they could be taken to the veterinary laboratory soon enough for disease investigation.
He said there were also some issues with the GPS tracker reliability.
"It was almost impossible to find cows if the alert was received when the collar was not working," he said.
"We usually had to wait until they came into the water trough to record those observations.
"The GPS collar problems were identified and an improved model was developed for use of the 2020-2021 calving season."
Despite the issues, it was possible to observe most cows within two days of calving in the 2019-2020 season.
This was due to the hot and dry weather conditions, which meant most cows congregated at a single water trough during the day, before leaving in the late afternoon to graze.
This allowed for daily visual checks on most cows and if calving cows could not be located using GPS data then observations were recorded when they came for water in the days after birth.
Mr Schatz said cows calved between September 9, 2019 and January 2, 2020 with "very dry and hot" conditions up until mid-December when the rains started across the Northern Territory.
"Calving sites of cows were dispersed quite evenly through the paddock, although some hot spots where calving was concentrated were identified," he said.
"The majority of cows either calved at night while away from the trough, walked away to calve in more private locations or did not come into the water point on the day they calved."
Heifers calving for the first time had a tendency to calve nearer to the water trough than the older cows.
The best performance recorded by the birthing sensors was calving alerts from 85pc of cows in the first calving season and for the GPS tracking collars was 74pc working when needed in the second season.
Calf loss rates were 17pc in both years of the trial, which was at the "high end" of the normal range for mature cows in northern Australia.
In both years of the study, rates were 6pc units higher than the average calf loss onsite in the previous four years.
The reason behind this was unknown, but Mr Schatz said it was likely due to the cumulative effect of several different factors including:
- The late start to the 2019-2020 wet season and very poor wet season (worst in 50 years).
- The extra activity of people in the paddock taking observations of cows at calving (although care was taken to disturb cows as little as possible).
- Trial camera photos revealed wild dogs were present in the paddock, but actual evidence of dog attack was quite low (2.5pc of calves with bite marks at weaning).
He said that even though care was taken to "disturb the cows as little as possible when they were calving", the extra activity of people taking observations may have contributed to higher calf loss.
"The project investigated the causes of calf loss and there were a number of minor causes (1pc or less) including abortion, dystocia, neonatal septicaemia via umbilical cord, pneumonia, deformity and wild dog attack," Mr Schatz said.
"However, unknown causes were the biggest cause of loss in both years (8pc in 2019 and 10pc in 2020).
"A portion of those losses - due to unknown causes - are likely to have been due to poor mothering including cows abandoning calves.
"This could not be quantified as efforts were made to not disturb cows that appeared agitated in case this exacerbated the problem.
"Also some cows were not observed after calving due to failure of birth sensors and tracking collars."
Bottle teats were another major cause of loss (6pc in 2019 and 5pc in 2020).
A number of cows were observed with bottle teats at calving, but their udders returned to normal several weeks after their calf died, and so they would not be identified as having bottle teats at muster several months later.
Mr Schatz said if the herd was representative of northern herds, it was likely that bottle teats were a bigger problem than previously thought and that cows with bottle teats were remaining in herds and losing multiple calves.
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