Resumen: Actigraphy uses triaxial accelerometers to study the locomotor activity (LA) of animals and humans, and proximity sensors are used to record interactions between individuals. This study documented the LA of a group of cows and their calves, and their interactions based on data collected by accelerometers that also served as proximity sensors. Mean LA of five cows and their calves, the temporal distribution in LA, and their circadian rhythms were calculated and the statistical significance of differences was assessed by an ANOVA. LA (counts/min) did not differ between cows (60.03±7.96) and calves (51.68±5.48), and were highest at 0900 h, and 1300 h, and 1900 h. Cows exhibited higher (P<0.001) LA in the day (96.05±7.99) than at night (38.42±7.48); in calves, the difference between day (63.84±7.67) and night (44.39±6.96) was not statistically significant. Mothers and offspring exhibited a 24-h circadian rhythm in their LA, which had a similar acrophase (12:45 vs. 12:14 h), but different MESOR (60.03 vs. 51.69) and amplitude (41.63 vs. 20.06) (P<0.05). On average, 34% of a cow’s proximity contacts were with their own calf. Cow-calf proximity contacts occurred throughout the day, but were most frequent around 0100 h, 0600 h, 1100 h, 1700 h, 1900 h, and 2100 h. The closest contacts (shortest distances) occurred at 0500 h, 1100 h, 1900 h, and 2300 h. The devices used in this study proved to be a useful for monitoring proximity between mothers and calves and their daily LA, in which both exhibited a 24-h circadian rhythm. Idioma: Inglés DOI: 10.31893/jabb.2025018 Año: 2025 Publicado en: Journal of Animal Behaviour and Biometeorology 13, 2 (2025), 2025018 [8 pp.] ISSN: 2318-1265 Tipo y forma: Artículo (Versión definitiva) Área (Departamento): Área Producción Animal (Dpto. Produc.Animal Cienc.Ali.)