Exploring diurnal feeding patterns of individual growing-fi nishing pigs under healthy and undisturbed conditions

In growing-fi nishing pigs, diurnal feed intake follows an alternans pattern, with an intake peak in the morning and a larger peak in the afternoon. Although this alternans pattern is reported at group level, for aggregated days, little is known about the diurnal feed intake of individual pigs from day to day. Therefore, we aimed to gain insight into the diurnal intake patterns of healthy individual pigs, exploring 1) which types of patterns exist and 2) whether individuals are consistent in their diurnal activity across days. Data was collected on 110 growing-fi nishing pigs (11 pigs/pen) using IVOG® electronic feeding stations (Hokofarm group), from arrival at the farm (average±stdev: 27.5±2.9kg) until slaughter (83d, 8d after 107±8.7kg). Sensor data was cleaned, aggregated at the hourly level and scaled at pig level by dividing hourly by daily intake. To study basal feeding patterns, putative deviating days (days surrounding health issues (1592d), after arrival (≈99*3d) and with farm visits (≈99*24d)) were removed from the dataset, leaving 4626 pig days (n=99 pigs) for analysis. Self- organising maps (dissimilarity based on weighted cross-correlation) combined with hierarchical clustering were used to visualise diurnal feeding patterns and their development in time. In addition, the weighted cross-correlation was used to quantify the consistency of individual pigs across days, creating graphs similar to autocorrelograms. Preliminary results identified a range of diurnal patterns, which could be summarised in 8 clusters. The clusters differed in the number, height, width and timing of intake peaks, and the most frequently occupied cluster reflected the alternans pattern (1113 days, 23.7%). Visualisations per month suggest younger pigs mainly feed throughout the day and night, while older pigs eat less frequently, in larger meals, during the day. Correlation coeffi cients at lag=1d were moderate to high for individual pigs (median: 0.61, range: 0.40-0.80), suggesting that pigs show similar diurnal patterns in adjacent days but some clearer than others. As the lag increased, auto correlation coefficients slowly decreased (e.g. lag=28d, median: 0.58, range: 0.28-0.75), reflecting a slow change in diurnal patterns over time. To conclude, preliminary results suggest that although pigs show an alternans pattern on many days, a range of other diurnal intake patterns can occur. Individuals show similarity in diurnal patterns from day to day, some pigs stronger than others, and shift their patterns slowly with age. As pigs deviate their feeding behaviour in response to welfare challenges, improved understanding of individual basal patterns can aid in isolating welfare-indicative variation