Walk over weighing for monitoring mobs of sheep without RFID tags

WOW has been developed by the Sheep CRC to record the individual weights of sheep in the paddock using Radio Frequency Identification (RFID) without human intervention.

Mob-based Walk Over Weighing (MWOW) is a newly commissioned project which aims to develop a walk over weighing system for monitoring mob or flock weight change without the necessity of RFID tags and readers. The system would deliver the average weight of sheep within a mob or group of animals and the standard deviation (SD) at any given time; and the average weight change of a mob over time. This would be used to enhance the on-farm decision making process for applications such as:

Weaner management, to detect weight loss trends prior to problems developing;
Supplementary feeding, to determine when to start and to enable fine tuning of feeding amount and management; and
Lifetime ewe management and monitoring.

To date, free flow walk over weighing systems using RFID tags to monitor the weights of individual animals have been produced and are available from Tru-Test. These have been developed and tested in the paddock and in feedlots using water as the attractant. In the paddock situation they provide weight accuracy of over 80%; and in feedlots over 70% accuracy. Software for data cleaning and analysis has been developed by Industry & Investment NSW and the Sheep CRC.

Without RFID tags, it is estimated that around 100 weights would be required from a mob of 1000 sheep to provide a sufficiently accurate estimate of mean and SD. It would appear that weekly weight estimates would be sufficiently frequent for most purposes.

While most monitoring/feeding situations are associated with dry periods when attraction to water can be used for weighing, the project needs to consider situations with multiple watering points such as creeks. Also attractant options independent of watering points will be investigated as these will be useful for monitoring animals are on green feed and not requiring regular access to water.