The ability to monitor average liveweight of a sheep flock provides livestock managers the opportunity to nutritionally manage their flock for higher productivity. Mob-based walk-over weighing (MBWOW) is a remote weighing concept for sheep flocks whereby liveweights are collected as the animals pass freely over a strategically placed weighing platform. We tested the hypothesis that the repeatability and frequency of MBWOW data are sufficient to generate sheep flock average liveweight estimates with a 95% confidence interval (CI) of <2 kg over a 5-day time period. These criteria were considered reasonable, in terms of accuracy and timeliness, for application in a commercial context. Radio frequencyidentifiedWOWdata were obtained from four sheep flocks in south-eastern New South Wales, representing a mix of age and breeds, as sheep traversed a remote weighing platform to and from some form of incentive. The repeatability and frequency of three forms of radio frequency-identified WOW data, being raw (unfiltered), course-filtered (filtered to remove all sheep weights outside the flock weight range) and fine-filtered (filtered to remove all sheep weights outside a 25% range of a recent flock average reference weight), were used in a simulation to test the 95% CI of 1- and 5-dayM BWOW liveweight capture periods (samples). All data-filtering approaches over a 5-day sample generated flock average liveweight estimates with 95% CI of <2 kg, thus meeting the hypothesis criteria. One-day samples generated flock average liveweight estimates with 95% CI of >2 kg and data filtering, although reducing the 95% CI, did not bring it below the hypothesis criteria. Thus, when the appropriate data handling technique is used, MBWOW may provide information suitable for sheep management decisionmaking in a commercial context.

The association between liveweight and a range of production and economic outcomes has been demonstrated in sheep production systems. Change in ewe liveweight affects her wool production, reproductive performance, survival and lifelong performance of her progeny. Similarly, liveweight in young sheep post-weaning is strongly associated with their survival. This breadth of sheep production parameters with demonstrated association with liveweight suggests that regular liveweight monitoring would provide a robust and versatile tool for managing sheep flocks. Walk-over weighing (WOW) technology has the potential to remotely monitor sheep liveweight either individually or collectively and is commercially available. It functions by collecting liveweight data as sheep voluntarily cross a weighing platform as part of their normal daily routine. The liveweight data is then collected, processed and interpreted by livestock managers to aid nutritional management. Despite the documented benefits of managing ewe liveweight, and the potential of WOW to aid ewe liveweight management, there is a paucity of literature on the subject. This thesis draws on a series of experiments, data analyses and economic models to investigate the factors affecting WOWs potential for commercial application.

Sheep liveweight is an indicator of nutritional status, and its measure may be used as an aid to nutritional management. When walk-over weighing (WOW), a remote weighing concept for grazing sheep, is combined with radio frequency identification (RFID), resulting 'RFID-linked WOW' data may enable the liveweight of individual sheep to be tracked over time. We investigated whether RFID-linked WOW data is sufficiently repeatable and frequent to generate individual liveweight estimates with 95% confidence intervals (95% CI) of <2 kg (a sufficient level of error to account for fluctuating gut fill) for a flock within timeframes suitable for management (1-day and 5-day timeframes). Four flocks of sheep were used to generate RFID-linked WOW datasets. RFID-linked WOW data were organised into three groups: raw (unfiltered), coarse filtered (remove all sheep-weights outside the flock's liveweight range), and fine filtered (remove all sheep-weights outside a 25% range of a recent flock average reference liveweight). The repeatability of raw (unfiltered) RFID-linked WOW data was low (0.20), while a coarse (0.46) and fine (0.76) data filter improved repeatability. The 95% CI of raw RFID-linked WOW data was 27 kg, and was decreased by a coarse (11 kg) and fine (6 kg) data filter. Increasing the number of raw, coarse and fine-filtered data points to 190, 30 and 12 sheep-weights, respectively, decreased the 95% CI to <2 kg. The mean cumulative percentage of sheep achieving >11 fine-filtered RFID-linked WOW sheep-weights within a 1-day and 5-day timeframe was 0 and 10%, respectively. The null hypothesis was accepted: RFID-linked WOW data had low repeatability and was unable to generate liveweight estimates with a 95% CI of less than 2 kg within a suitable timeframe. Therefore, at this stage, RFID-linked WOW is not recommended for on-farm decision making of individual sheep.