Document type: scientific article published in Computers and Electronics in Agriculture
Authors: Lydiane Aubé, Bruno Meunier, Romain Lardy
Preview: Grazing cows preferentially access shade to shield themselves from the sun. However, the conditions that provide cows with optimal shade access and use (e.g., no competition for access to shade) are still unknown. Continuous monitoring of shade use by grazing cattle could help to understand how and when cows use shade resources. The aim of this study was to validate a method based on a light sensor (HOBO Pendant MX2202) attached to the back (on the transverse processes of the lumbar vertebrae) of 7 dairy cows at pasture to continuously record their use of natural shade for research purposes. Live behavioral observations of shade use and cow posture were recorded in summer (June to September, between 9 a.m. and 6 p.m.). Based on the behavioral observation data, we determined thresholds in lux to discriminate between cows in shade and cows in sun on a randomly-generated training dataset representing 15% of the initial dataset. This process was repeated 100 times, generating 100 thresholds and threshold performances. Data loss due to sensor loss or battery discharge was 9%, which is acceptable. The thresholds ranged from 15,688 to 40,556 lx: sensitivity ranged from 92.0% to 99.8% and specificity ranged from 88.7% to 99.9%, showing that the performances were robust to threshold variation within this range. This study demonstrates that an efficient threshold to discriminate cows in shade from cows in the sun can be determined via a relatively short (about 12 h) series of live observations. As performance seems to be slightly lower for lying cows than for standing cows (mean false-positive rate is 7.4% for lying cows versus 1.8% for standing cows), future studies should consider posture (which can also be monitored continuously with other sensors such as accelerometers installed on the legs or neck collars of cows).
Publication that led to an article on the INRAE website on 02/25/2026
