Calf Watch – Developing a system to remotely monitor calving and study calf loss in extensive situations in Northern Australia

Introduction

Calf loss is a major source of lost income for northern beef producers and it has been estimated that neonatal calf loss costs north Australian cattle producers in excess of $53 million annually. Reducing calf loss has potential to improve weaning rates and profitability for northern cattle producers. In northern Australia it is not uncommon for calf loss to exceed 30% in first calving heifers and 15% in cows; halving these losses would provide significant benefits, however previously it has been difficult to investigate the causes of and improve the rate of calf loss, as calving females are difficult to find in large paddocks. Additionally, calf carcasses are difficult to find under extensive conditions making autopsies to determine the cause of calf deaths difficult.

The development of a system that could remotely monitor calving in extensive conditions such as those experienced in northern Australia would provide great benefits for research into the causes of calf loss in this location.

It is suspected that the incidence of calf loss is increased when calving occurs a long way from water points in large paddocks and thus reducing paddock size may reduce calf loss rates. Unfortunately, there is currently little scientific evidence for this and so it is difficult to justify spending large amounts of money on infrastructure without proof that it will have the desired effect.

Researchers at the University of Florida have developed a system to remotely monitor calf loss by modifying an existing “barn” system of birthing sensors. The Calf-Watch project aims to collaborate with theses researchers to adapt their system for use in northern Australia, using it to assist in the investigation of the causes of calf loss.

Ultimately this research has the potential to reduce calf loss and improve incomes for northern beef producers.

Materials and methods

After the conclusion of the pilot study where expelled birthing sensors were difficult to locate, modifications were made to the system to include GPS collars on the monitored cows and Bluetooth beacons in the sensors that is activated upon expulsion. The location data is viewable in real time on a website maintained by the company that produces the GPS collars (Smart Paddock).

The remote calving monitoring system uses intra-vaginal birthing sensors that start emitting a UHF signal when a rapid temperature change is detected, such as when they are expelled during calving. The signals are received by antennas in a low-power wireless-area network (LPWAN) and are transferred by a gateway, via the internet to servers owned by the sensor manufacturer (JMB). A calving alert email is then sent and is also immediately viewable on a website.

Four gateways with external antennas were mounted on 12 m high towers to give adequate coverage of the 2,215 ha uncleared paddock of native pasture (which was approximately 7.7 km long and 6 km wide at the widest point). Each tower had a read range of about 1.8-2 km in 360 degrees from the tower. On 14/8/2019, 189 pregnant cows were fitted with birthing sensors and GPS tracking collars. Another 10 cows were fitted with GPS collars but not birthing sensors.

Results and discussion

It was very hot and dry during most of this time with mean maximum temperatures of 39.8oC, 40.4oC and 40.8oC in October, November and December respectively (BOM 2020), and cows congregated around the single water point for most of the day before leaving in the late afternoon to graze. This allowed daily visual checks to be made on most cows and if calving cows could not be located using GPS data (eg. if the GPS collar was not working at the time of calving) then observations were recorded when they came for water in the days after calving. Also observations were recorded on any cows that were seen to have calved before an alert was received. Rain fell in December, after which the cows no longer congregated near the water point for most of the day and this made it difficult to locate cows if they did not have a working GPS collar. As a result four cows that calved in late December were excluded from the study as they had not yet been found for observation.

Expulsion alerts were received from 71% of sensors soon before calving. A different type of alert was received from a further 27 sensors which evaluation of calving observations found could be interpreted as an expulsion alert as they were received just before calving. If these are included in the total number of sensors that recorded an alert before calving then 85% (158 of 185) of sensors were successful in remotely identifying calving. Of the sensors that did not give an alert correctly; four sensors were expelled early (more than one month before calving), two alerts were received after cows had been observed to have calved, and no alert was received from 21 sensors. Failure of these 21 sensors is difficult to assess, but could be due to internal malfunction (equipment failure), or inability of a base station to receive a signal due to the location where they landed on the ground (environmental interference).

This study found that the birthing sensor system was quite successful in remotely identifying time of calving even though the high temperatures during the study would have often been similar to the body temperature of cows and so there would not have been a large change in temperature to trigger activation to beacon mode. Theoretically the birthing sensors have enough battery life to be used two or three times but locating expelled sensors in a large paddock with many trees and tall grass is virtually impossible without GPS tracking. Most of the expelled sensors were found if the cow had a working GPS collar at the time of expulsion, but few were found if it did not. The birthing sensors would be improved if they had GPS capability and sent the location of expulsion with the alert.

Preliminary publications

Calf-Watch project Brahman cows fitted are fitted with GPS collars and birthing sensors (not able to be seen in image) stand under trees near a supplement shelter with research scientists and Tim Schatz.
Calf-Watch project cows fitted with GPS collars and birthing sensors will allow scientists to determine the cause of early calf death in the extensively managed rangelands of the Northern Territory.

Project details

Calf Watch is co-funded by Meat & Livestock Australia and the Northern Territory Government and is due to conclude in October 2020.

For further information about Calf Watch, contact Tim Schatz, Principal Beef Research Scientist, Northern Territory Department of Primary Industry and Resources on 08 8999 2332.