Departamento de Zootecnia, Mediterranean Institute for Agriculture, Environment and Development (MED), Universidade de Évora, Évora, Portugal.
Master 1 Biologie-Agronomie-Santé, Parcours Comportement Animal et Humain Université de Rennes, Rennes, France.
PLoS One. 2022 Mar 18;17(3):e0265037. doi: 10.1371/journal.pone.0265037. eCollection 2022.
Grazing patterns, intake structure, and diet selection are dynamic responses to animals' feeding environment. This study uses video sequences from animal-borne cameras to capture time- and scale-dependent grazing behaviour variables related to sward explanatory conditions. We observed grazing 'through' the sheep's eyes using point-of-view (POV) cameras coupled with event logging software. Time-specific sward features were measured by sampling 'really' grazed patches identified by applying a global navigation satellite system (GNSS) precision-grazing approach. Sward variables on a Mediterranean native sward were measured for two years during the active spring plant-growth cycle. Overall, the results demonstrate that POV cameras were able to capture grazing behaviour fine-tuning to changes in sward characteristics. Sheep compensate for the decrease in sward quantity and nutritive value by increasing the size and duration at each behavioural scale (i.e., meal, bout, and station) while increasing the bout rate and decreasing the station rate. Diet composition also changed as sward matured. The proportion of forbs in the diet remained high in early and late spring, and forbs and legumes were preferred to grasses in early spring. Grazing selectivity was more pronounced in late spring, with sheep favouring the middle stratum of the sward's vertical structure, preferring green vegetative material, while enlarging the feeding niches' span and spending more time at each niche, consequently reducing the station rate. Although data collected by individual animal-borne POV cameras were representative of the flock behaviour, they may underestimate the total grazing time outside major meals. The results indicate that the use of animal-borne video cameras is suitable for assessing variations in sheep grazing behaviour patterns in complex swards.
放牧模式、采食结构和饮食选择是动物对其采食环境的动态响应。本研究利用动物佩戴的摄像机拍摄的视频序列，来获取与草地解释条件有关的、具有时间和尺度依赖性的放牧行为变量。我们使用与事件记录软件相连接的视角（POV）摄像机，从羊的视角观察放牧行为。通过应用全球导航卫星系统（GNSS）精确放牧方法来识别“真正”被放牧的斑块，以此对特定时间的草地特征进行采样。在春季植物生长活跃周期的两年间，对地中海本地草地的草地变量进行了测量。总的来说，研究结果表明，POV 摄像机能够捕捉到放牧行为对草地特征变化的精细调整。绵羊通过增加每个行为尺度（即采食、采食回合和站立）的采食大小和时长，同时增加采食回合频率并降低站立频率，来补偿草地数量和营养价值的下降。随着草地的成熟，饮食组成也发生了变化。早春和晚春，饲草在饮食中的比例仍然很高，早春时，饲草和豆科植物优先于禾本科植物。晚春时，放牧选择性更为明显，绵羊偏爱草地垂直结构的中层，偏好绿色的营养物质，同时扩大了采食生境的跨度，并在每个生境上花费更多时间，从而降低了站立频率。虽然单个动物佩戴的 POV 摄像机采集的数据可以代表羊群的行为，但它们可能低估了主要采食之外的总放牧时间。研究结果表明，使用动物佩戴的摄像机适合评估复杂草地中绵羊放牧行为模式的变化。
