Estimating the energy expenditure of farm animals at pasture is important for efficient animal management. In recent years, an alternative technique for estimating energy expenditure by measuring body acceleration has been widely performed in wildlife and human studies, but the availability of the technique in farm animals has not yet been examined. In the present study, we tested the potential use of an acceleration index, overall dynamic body acceleration (ODBA), as a new proxy for estimating the energy expenditure of grazing farm animals (cattle, goats and sheep) at pasture with the simultaneous evaluation of a conventional proxy, heart rate. Body accelerations in three axes and heart rate for cows (n = 8, two breeds), goats (n = 6) and sheep (n = 5) were recorded, and the effect of ODBA calculated from the body accelerations on heart rate was analyzed. In addition, the effects of the two other activity indices, the number of steps and vectorial dynamic body acceleration (VeDBA), on heart rate were also investigated. The results of the comparison among three activity indices indicated that ODBA was the best predictor for heart rate. Although the relationship between ODBA and heart rate was different between the groups of species and breeds and between individuals (P<0.01), the difference could be explained by different body weights; a common equation could be established by correcting the body weights (M: kg): heart rate (beats/min) = 147.263∙M -0.141 + 889.640∙M -0.179∙ODBA (g). Combining this equation with the previously reported energy expenditure per heartbeat, we estimated the energy expenditure of the tested animals, and the results indicated that ODBA is a good proxy for estimating the energy expenditure of grazing farm animals across species and breeds. The utility and simplicity of the procedure with acceleration loggers could make the accelerometry technique a worthwhile option in field research and commercial farm use.

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The piezoelectric photoacoustic (PPA) spectra were successfully observed between liquid nitrogen and room temperatures for undoped (n-type) and N-doped (p-type) ZnSe epitaxial layers on a GaAs substrate grown by molecular beam epitaxy (MBE). Four different nonradiative recombination centers due to lattice defects are obtained in the nondoped and the N-doped sample. In the N-doped ZnSe, the lattice defects with an activation energy of (180 AE 5 meV are considered to be N Se ±Zn±N Se complex acceptors. Three other peaks of nonradiative centers are due to intrinsic defects in the N-doped sample, since they are also obtained in nondoped samples. We have obtained nonradiative recombination centers in N-doped p-type ZnSe thin films grown by MBE for the first time.

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