A pilot study evaluating the behaviour of grazing sheep feeding on an anti-methanogenic feed additive from an automated feeder

Context. Regular provision of feed additives to reduce ruminant methane production has shown promising outcomes; however, appropriate carrier pellet delivery systems for grazing sheep are lacking. Aims. This pilot study investigated the behavioural and social patterns of grazing sheep when offered Asparagopsis-treated pellets by using a modified Nedap electronic sow feeder (ESF). Methods. Seventy grazing Merino wethers were divided into two equal groups, with the first group being put in a paddock with the feeder for 35 days before the second group was introduced. During the first 21 days, the feeder was programmed to deliver 30 g of pellets per sheep, six times per day, then increased to eight times per day for the remainder of the study. Parameters recorded by the Nedap for each visitation by sheep included feeder entry and exit time and whether or not pellets were dropped. Additional behavioural parameters were annotated from video recordings, including aggressive interactions, whether sheep finished eating and causes of incomplete feeding. Key results. In Group 1, 82.3% of the sheep visited the feeder, with 4.4 ± 0.3 (mean ± s.e.) feeding visits per day. In Group 2, only 28.6% of the sheep visited, averaging only one feeding visit per day. The daily mean feeder occupation time after feed was dispensed ranged from 69.6 ± 3.5 to 77.5 ± 1.4 s. In Group 1, animals that used the feeder had at least 8% lower mean daily visit frequency in Weeks 6 and 7 compared with other weeks. In Group 2, the mean feeder visit was at least 26% higher in Week 9 than in Weeks 7 and 8. Displacement by other sheep was the main reason for incomplete feeding events, followed by self-initiated disturbance. Conclusions. Grazing sheep successfully learnt to consume supplementary feed multiple times per day from the ESF. However, the lower participation rate of Group 2 could indicate a need for training and/or fewer animals per feeder. Implications. Further research to evaluate the impacts of training periods, social learning, and dominance with multiple groups of sheep and multiple feeders within a paddock will contribute towards recommendations for producers on how to effectively deliver anti-methanogenic supplements with electronic feeders to sheep at pasture.