This invention relates to a passive system for the identification of remote movable objects together with a capability of storing and transmitting information uniquely associated with that object. This invention is related to U.S. patent application Ser. No. 406,471, filed Aug. 9, 1982, now U.S. Pat. No. 4,510,495 and entitled "Remote Passive Identification System" now U.S. Pat. No. 4,510,495.
This invention utilizes the identification and transmission aspects of that co-pending application and enhances the system by providing for data collection and storage of parameters unique to the identified object. As in the case of U.S. Pat. No. 4,510,495, this invention has particular utility in livestock management.
Advances in microelectronics have been applied to systems employing coded transponders associated with an object to be identified and engergized by interrogator burst pulses, such that a transmission of coded information signals unique to the object carrying the transponder is generated. Such techniques, when pursued in the dairy industry, allow for efficient herd management by identifying each animal. For example, with cows, once identity has been established, additional data associated with that individual cow may be collected and appropriate action taken. Herd management, therefore, requires in the first instance the identification of the animal such that monitoring of health, reproductive status, allocation and distribution of feed and production (i.e., milk in the case of cows) can all be monitored.
In the context of dairy herds, estrus detection is an important aspect of herd management. Estrus detection rates have a direct influence on the profitability of the herd as a function of calving interval. The optimum calving interval is approximately twelve months. A longer interval results in decreased milk production per cow per day and fewer calves. At present there exists no reliable automated technique of estrus detection on dairy farms. Manual, visual observation and pedometers are typical of attempts based on increased activity of the animal to detect estrus. Those techniques are accurate provided the farmer has sufficient time for observation of the animals. It has been estimated that the present average estrus detection rate is in the range of 40-60%. Given the clear dependency of herd profitability on this detection rate, a need exists for a system employing a reliable estrus detection technique which can be used in the context of contemporary herd management systems.
Reference is made to U.S. Pat. No. 4,247,758. The animal identification and estrus detection system, described therein, employs an activity sensor/recorder, a transponder, an interrogator and an information processing unit. The motion sensor is a mercury switch/battery combination. Motion by the animal wearing the sensor causes the mercury switch to close, which produces a voltage pulse incrementing a binary counter. The sensor defined in U.S. Pat. No. 4,247,758 outputs a voltage pulse of constant amplitude whenever the switch is opened and closed. This constant amplitude pulse is generated independent of force and velocity of motion provided the force is sufficient to close the mercury switch. Consequently, the system cannot detect between various types of motion.
A major disadvantage of the U.S. Pat. No. 4,247,758 system is that it requires a power supply for the sensor and counter. That is, the device carried by the animal is an active device necessitating the use of a battery to power both a sensor and the counter. The requirement of a battery is of considerable importance in application of such devices to animals. For example, a battery operated device must be removed periodically to change batteries which is a potentially arduous task in large herds. The requirement for a battery adds considerable weight and cost to the individual devices. Consequently, a system which eliminates a battery represents an important improvement in this technology. A battery free device may, for example, be implanted in the animal. Even if not implanted, it may remain on the animal over the lifetime of the device or the animal without maintenance.