Animal Industry Report

Extension Number

ASL R3166



Summary and Implications

Heat stress (HS) is an annual environmental issue which negatively affects a variety of production parameters including milk yield and composition, growth, and reproduction. A study was conducted toexplore the efficacy of an electric heat blanket (EHB) as an alternative method to study HSand to determine whether EHB-induced hyperthermia affects production parameters similar to natural HS.During this study, the animals were fitted with an ear tag based behavior and temperature monitor (Cow Manager, Agis Automatisering, Netherlands) toevaluate behavior and ear temperature changes through the heat stress study and understand the potential use of behavior monitors in the field for early heat stress identification and mitigation. Also 24 hr continuous time lapse video was captured on all animals during their time in the trial barn. Data from this trial is being analyzed. This paper presents behavior and temperature graphs, data, and comments from one animal over her trial period. When animals were moved to the trial barn, ear temperatures increased to 80-950F and remained there for the 2 week barn period indicating increased blood flow to the ear for heat dissipation. Ear temperatures were highest during the blanketed period. There were some daily and diurnal changes associated with external temperatures (barn had curtains). Mostlyanimals rested with heads toward outside cooler walls, evidencing animal behavior to mitigate heat load. Ear temperatures dropped immediately and returned to normal when returned to colder herd free stall barn. Compared to baseline daily normal activity % (eating, ruminating, non-active, active, and highly active), changes were seen when animal were moved to the barn or in the barn (increased activity, perceived increased eating but related to more head movement due to environment adjustments rather that truly eating). During week 1 in the barn (warmer barn but no blankets), behavioral changes captured included decreased eating times (15-18% vs. 25-27% normally) but uniquely increased rumination times (which were associated with increased respiration and panting activity rather than rumination). Once the blanket was applied for 1 week, further behavioral changes were seen with daily eating times decreased to 8-10% (also changes when animals ate -mostly only when moved to milk) but rumination times increased (65-75%) but was associated with increases in respiration and panting movement rather than rumination. When blankets were removed and animals returned to normal freestall, ear temperatures immediately adjusted and dropped to normal but behavior changes to normal took 1-6 days. Overall, the electric blanket heat stress model was successful and behavior and ear temperature monitors were very successful in quantifying changes associated with heat stress (earlywith slightly warm temperatures through higher temperatures associated under the blanket). Accelerometers were excellent in measuring movement but newer algorithms need to separate random head movements from true eating, and mouth movements with no other movements associated with panting from rumination to improve diagnostic performance. Overall, the monitors look like an excellent technology to observe changes in early moderate heat stress and provide a tool for implementing early heat stress management and mitigation strategies.



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