Variation in and relationship among environmental condition and total locomotor activity in dairy cows

Introduction - Behavior is one of the most important indicators for assessing cattle health and welfare. The cow comfort improves economically important responses in dairy cattle such as feed intake, milk production, reproduction and health. The environmental variation in air temperature, relative humidity and rainfall were recognized as the potential hazards which affect the animal’s biological system. Aim - The aim of this study was to investigate the influence of environmental conditions (ambient temperature, relative humidity and temperature-humidity index) on the total locomotor activity (TLA) behavior in dairy cows. Materials and methods - 18 Modicana cows (5-8 years, mean body weight 512±78 kg), selected from two different farms (A and B), were enrolled in the study. During experimental period, ambient temperature and relative humidity were recorded by means of a data logger and the temperature-humidity index (THI) was calculated as indicator of thermal comfort for cattle. Each animals were equipped with an activity monitoring data loggers (Actiwatch-Mini®) in order to record the daily TLA. Results and discussion - The results of the present study confirmed that the TLA is influenced by environmental conditions. The ambient temperature and THI recorded during the experimental periods were within the upper critical zone. Two-way repeated measure analysis of variance (ANOVA) a significant effect of season (P < 0.0001), whereas no effect of farm on the amount of TLA was found. A trigonometric statistical model was used to describe the main rhythmic parameters: mean level, amplitude, acrophase and robustness of rhythm. Our results showed a circadian rhythm of daily TLA in all periods, with different percentages of robustness, and acrophase in the photophase. Conclusions - These results provide insight into the TLA responses of dairy cow to different environmental conditions, allowing to better evaluate its ability to adapt and cope with environmental stress. Major changes in TLA were found at the hottest environmental condition therefore suitable measures should be adopted in order to minimize environmental stress and to improve animal welfare.