Technical note: An acoustic method for assessing the respiration rate of free-grazing dairy cattle

Abstract The aim of this study was to validate whether acoustic data analysis can be used to assess respiration rate (RR) in dairy cattle under grazing systems. Two validation trials, one with heifers and other with lactating cows, were conducted. The RR derived from acoustic data acquired with an MP3 recorder fitted on the halter was compared to the RR derived from a visual method, counting flank movements. Data were analyzed using correlation test and Willmott's index of agreement (d). There was no significant difference (P>0.05) between RR assessed using the acoustic or visual method, in both heifers and lactating cows. The coefficients of determination (R2) indicated that 92.31% (heifers) and 62.09% (lactating cows) of the variability in the RR derived using the visual assessment method was explained by the RR derived using the acoustic method. The d values were 0.99 (heifers) and 0.98 (lactating cows), which denoted good agreement between the RR derived using the two methods. The acoustic method is non-invasive, allows for the assessment of RR in free-grazing dairy cattle and may replace the current standard of visual counting.