BIBLIOGRAFÍA

The Kahne boluses and transceivers showed the ability for measuring the temperature, pressure, and pH in the rumen of cows and sheep on a real time bases. This technology is useful on not only in scientific research but also for commercial use. The ruminal pH, temperature, and pressure are important parameters for health in ruminants. Ruminal pH is used as a parameter of health in cattle (Bramley et al, 2003; Kleen et al, 2003). Monitoring the pH in the rumen could assist in preventing ruminal acidosis (Oetzel, 2003; Krause and Oetzel, 2006; Al Zahal et al, 2007; Nagaraja and Titgemeyer, 2007). Temperature in the rumen also indicates the healthiness of the animal. Disease events such as Bovine Viral Diarrhea Virus (BVD) and Bovine Respiratory Disease (BRD) commonly result in an increase in core body temperature (Dye et al, 2007). It was suggested that ruminal temperature may aid in the detection of SARA (Al Zahal et al, 2008). Monitoring ruminal pressure could help in detecting bloat in cattle, especially for cattle in the feedlot that are offered large amount of highly fermentable grains (Theurer, 1986; Cheng et al, 1998). Using Kahne boluses and transceivers that enable the real time observation of ruminal pH, temperature, and pressure could allow first hand treatment of problems when they were detected.

technologies enable the measurement of signals or multiple aspects in the rumen (i.e. pH, temperature, and pressure).

4.8.1 Technologies of measuring rumen temperature

The technologies developed for measurement of rumen temperature including using fistulated animal (Bhattacharya and Warner,1968; Brod et al, 1982; Al Zahal et al, 2007; Al Zahal et al, 2008), using Radiosonde equipment (Dracy et al, 1963) and using FM-AM temperature-sensitive radio transmitting units and telemetering system (Kurtenbach and Dracy, 1965; Darcy and Kurtenbach, 1968), and using the temperature boluses that are available in the United States for measurement of the rumen temperature of feedlot cattle (Dye and Richards, 2007; Dye et al, 2007). Among these technologies, only temperature boluses were designed for both scientific and commercial use. The rest were for scientific research only. In 1963, Darcy et al reported an experiment using radiosonde equipment and transmitter to measure the intra-reticular temperature of intact cattle. The radiosonde equipment has a range of 5 feet (1.67 meters) and had to be placed close to animal. The use of a U.S. Army signal receiver and the close range meant that it could only be used for scientific research. Darcy and Kurtenbach (1968) described the FM-AM temperature telemetering system for monitoring ruminal temperature in intact, unrestrained cattle. The telemetry system covers a 30m2 area for animal to move freely and the transmission units have battery lifetimes of 60 days. The limitations for this technology are the expensive equipment (at that time) and the temperature drift, which happens when the power is low in the transmission unit. The use of rumen fistula is very popular as a research practice to monitor the rumen environment, for example the measurements of ruminal temperature through the fistula. Bord et al (1970) used thermistor probes through the fistula of cattle and a scanning tele-thermometer to monitor the ruminal temperature in one study. Al Zahal et al (2007) described a system for continuous recording of pH through rumen fistula. The electrode was able to measure pH and temperature

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simultaneously. The receiver for that device was mounted on cows back to allow them to move freely and the battery allows one year of data recording. Calibration was performed to eliminate drift if necessary. Dye and Richards (2007) tested temperature boluses and used them to monitor rumen temperature of feedlot cattle (Dye et al, 2007). The studies gave positive feedback on using temperature boluses in commercial feedlots. They identified an advantage of detecting core body temperature, an early warning of health events. It was also concerned with bolus problems including the data from boluses that were not received, and no reading or abnormal readings for the boluses.

The Kahne boluses have the advantages of being able to be used in intact animals and being able to measure pH, temperature, and pressure. The technology described by Al Zahal et al (2007) with fistulated animal may have the advantage of more accurate data recording, but the use of a fistula is not appropriate for a large number of animals or commercially. Temperature boluses (Dye and Richards, 2007) have many similarities to the rumen boluses but they lack the ability to study the relationship between pH and temperature in the rumen.

4.8.2 Technologies of measuring ruminal pressure

Rumen pressure or rumen motility was measured by technologies such as using radiosonde telemetry transmitters (Darcy and Kurtenbach, 1965) and a radio telemetering capsule and demodulator (Cook and Riley, 1970; Riley and Cook, 1974; Riley, 1986). The radiosonde telemetry transmitters described by Darcy and Kurtenbach (1965) can send a signal approximately 20 feet (6.67 meters), allowing the animal to move freely within that range. Riley (1986) used a pressure sensitive capsule for monitoring rumen activity in an intact animal. The transmission units were inexpensive, commercially available and could last for several weeks. Kahne boluses are similar to the pressure sensitive capsule (Riley, 1986) in the sense of measuring ruminal pressure data and transmitting the signals. But with the ability of measuring

pressure with pH and temperature simultaneously, the boluses are much more useful in both scientific research and commercial use.

4.8.3 Technologies of measuring ruminal pH

Ways of measuring ruminal pH were described in section 1.3 in the literature review. The boluses are less invasive than rumen stomach tube, rumenocentesis and rumen fistula. The ethical cost is minimized if boluses were used. In scientific research, both rumen stomach tube, rumenocentesis and rumen fistula have proved to measure ruminal pH effectively (Nordlund and Garrett, 1995; Nordlund, 2003; Al Zahal et al, 2007). The Kahne boluses are still in the testing phase but the results are positive. The Kahne boluses are also the only commercial available products suitable to be used on a large number of animals for pH monitoring (e.g. feedlot).

4.8.4 Overall comparison

In scientific research, only the continuous recording system of pH through rumen fistula (Al Zahal et al, 2007) and the Kahne boluses have the ability of allowing animal to move freely and measuring more than one parameter in the rumen (i.e. ruminal pH and temperature). Temperature boluses (Dye and Richards, 2007) also allow free movement but only measures rumen temperature. Both technologies are good at measuring and collection data in an intensive period.

In commercial business such as a dairy farm or a feedlot, only the Kahne boluses and the temperature boluses enable measurements over longer periods of time for a large number of animals. By using these two technologies, the costs associated with frequent handling of animals could be minimised.

The Kahne bolus appears a better technology compared to other existed technologies. Firstly, it is available for both scientific research and commercial use. Secondly, it can simultaneously measure three parameters in the rumen. Thirdly, it can measure in short intervals (minimums 5 seconds) to closely monitor changes over short time frames or

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with less frequent transmission over longer intervals, allowing a long period of recording (up to 3 months). Fourthly, the reliability of transmission should be improved further and the pH drift problem should be rectified to enable measurement over longer periods.