Influence of environmental climate conditions on animal welfare criteria of lactating dairy cows

bjective Naturally ventilated barns (NVB) are affected by climate-related changes. The influence of environmental climate on animal welfare of lactating dairy cows was investigated. Material and Methods This study was carried out at a NVB in Germany (Holstein Friesian cows; 1st to 8th lactation; daily milk yield 38.2 ± 9.4 kg). The relative humidity (RH,%) and ambient temperature (T,⁰C) were measured in 5-min intervals with 8 EasyLog USB 2+ sensors (Lascar Electronics Inc., USA) and in 10-min intervals with 2 LogTags (HAXO-8, LogTag Recorders, New Zealand). The Temperature Humidity Index (THI) was calculated according to NRC (1971). Respiration rate (RR, visually counted hourly in 30 sec.), rumination activity (RA, recording with microphone in 2h-periods) and activity behavior (AB, IceTag3DTM-Pedometer at hind leg recording body posture every sec.) are used to characterize heat stress. Results RR: Cow-related factors (body posture, milk yield performances) and THI influenced the RR of lactating dairy cows. The values of RR in lying cows were greater than in standing cows. An increase of RR was observed per additional produced kg milk per day. RA: RA followed feeding times, but it was affected by environmental climate conditions, too. Cows spent more time on rumination during the late evening and the night, when THI was the lowest. The rumination time decreased strongest with increasing THI from 1600 to 2000h. AB: The duration of lying per day decreased by increasing ambient temperature and the duration of standing rose, but the duration of moving remained constant. The strongest changes in behavior could be recorded during the afternoon