An Ambulatory Data-logger Apparatus for Determining Heart Rate of Horses Grazed on Pastures.

Abstract

An ambulatory data-logging system for recording heart rate and/or the R-R interval in horses was developed. This system consisted o f a pulse generator for detecting heart beats and a data memory apparatus. The pulse signal generated by the pulse generator was fed to the data memory apparatus, and the heart rate and/or R-R interval was measured . The heart rate o f a riding horse was recorded for over 24 h and the accuracy in determining heart beats was monitored with an ambulatory EGG recorder. False beat counts were 0 .04% of total heart beats during the housed period and 1.6% during the grazing period in a paddock . It was thought that this system might become a useful tool to use in studying behavior and physiology based on the heart rate and/or R-R intervals in free-ranging horses. Keywords: ambulatory data-logger, heart rate, horse, R-R intervalIn the field of animal management, pasture management and animal behavior, a continuous recording of the heart rate is important in estimat ing heat production [12], daily energy intake [7], physiological adaptation and behavior [3,4,10,11,15]. A telemetry system for monitoring the heart rate is not well suited to large fields, because the range of a standard medical telemetry system in Japan is limited [8]. The Holter electrocardio graph is used for monitoring the electrocardio gram or heart rate in the field of veterinary medicine [13], but the data-analysis is expensive , and the data-analyzing software is not necessarily suited to various kinds of domestic animals. In recent years portable heart rate meters have been developed, and used in studies of exercising horses [1,2,14], but they cannot measure the R-R interval, and also cannot be connected to another measuring apparatus. In the present study, there fore, an ambulatory data-logging system for re cording the heart rate and/or R-R intervals in horses was developed.The heart rate memory apparatus (standard type or 64 K byte type, T.K.K. 1850a,1876a, Takei Scientific Instruments, Tokyo) used as a data memory apparatus in the present study was developed for human subjects, but it can measure the heart rate in cattle as well as in humans accurately [6] because the heart rate and ampli tude of the QRS complex are in the same range. The properties of this apparatus mean that it is capable of determining heart beats accurately when a QRS complex ranging from about 0.6 mV to 1.4 mV is input into the apparatus and the heart rate ranges from about 40 beats to 255 beats per min.The heart rate in horses could not be measured accurately using this apparatus, because the ampli tude of the QRS complex in horses is generally greater than in the human and cattle, and the heart rate is markedly lower than that in human and cattle [5,6]. In the present study, therefore, a pulse generator (Takei Scientific Instruments, Tokyo; made for a trial) for detecting heart beats in horses was developed. The pulse generator generates pulse signals of heart beats, these signals are fed into a heart rate memory apparatus and the number of ...

Relationships between Diurnal Variation in R-R Interval and Feeding Behavior in the Horse.

“…The variation of the R-R intervals can be analyzed by continuous measurement with the electrocardiogram and it is used to assess the effects of autonomic nervous activity on the cardiac function [1, 3,9]. We developed ambulatory data-logging systems for recording heart rate, R-R intervals [6] and the number of jaw movements per min [5,7,8]. Feeding behavior is characterized automatically by the number of jaw movements [5][6][7][8].…”

“…We developed ambulatory data-logging systems for recording heart rate, R-R intervals [6] and the number of jaw movements per min [5,7,8]. Feeding behavior is characterized automatically by the number of jaw movements [5][6][7][8].…”

“…Measuring apparatus: Heart rates (beats per min) and R-R intervals were recorded simultaneously by a combination of two heart rate memory apparatuses (64 K byte type and improved type, Takei Scientific Instruments, Tokyo) and a pulse generator for detecting heart beats in horses (made for trial use by Takei Scientific Instruments, Tokyo) developed previously [6]. The ready-made 64 K byte type apparatus measured heart rate, and the improved one measured R-R intervals.…”

“…The heart rate memory apparatus can store 32,768 successive R-R intervals in one recording session [7]. It is therefore necessary to load down the data into a computer once before the data storage capacity is exceeded, that is, within about 12-h, if the average heart rate in the horse is about 40 beats per min [6]. with a multi-channel data logger (Takei Scientific Instruments, Tokyo) [8].…”

“…1 indicates heart rate, jaw movements and the number of dropped beats each minute during 24-h. Dropped beats could be monitored from the series of R-R intervals recorded, and these dropped beats were regarded as seconddegree A-V blocks, because the R-R interval in the dropped beats was almost twice as long as those before and after the block [2, 6,11].…”