Develop a Faster Thermometer for Use in Cattle

Background

Measuring rectal temperature is a key step in identifying animals that are sick. Taking an animal’s temperature is one of the few practical methods to diagnose feedlot diseases like BRD. However, currently available thermometers require up to 30 seconds or more to get an accurate reading. This extended time frame can have a negative effect on animal welfare and limits the usefulness of the tool when handling groups of animals.

Objectives

• Develop and validate a new and more rapid thermometer.

What They Did

These researchers have developed and tested a novel digital thermometer and infrared temperature probe that measures bovine rectal temperature near instantaneously to aid in the diagnosis of BRD. This project proceeded through 3 phases. In order to move onto the next phase, individual phase objectives had to be met. The first phase involved the development of the novel digital thermometer and infrared temperature probe. The probe was 3D printed in medically safe plastic and made water resistant and robust, with an optical window on its end to allow the temperature sensor placement into the animals’ rectum. The second phase involved laboratory testing of the novel thermometer against a verified GLA thermometer and an ASTM-certified thermometer to evaluate temperature measurement accuracy and compare the times required to take measurements. The measurements were taken in the water bath, with the GLA and novel thermometer inserted at the same time to allow calculation of time to reach maximum temperature. The third phase involved field testing of the novel thermometer in mixed beef-breed feedlot cattle. Continuous temperature measurement was taken every 0.5 seconds on the novel and GLA thermometer to allow calculation of time to reach maximum temperature.

What They Learned

The results from Phase 2 showed that the novel thermometer was not as accurate as the GLA thermometer, reaching maximum temperatures below or above the ASTM-certified thermometer by 0.5 to 1°C based on at-the-time firmware settings, while the GLA thermometer reached the same temperature as the ASTM thermometer in all comparisons.

For the first trial in Phase 3, the average maximum temperature for the novel thermometer was lower than the GLA thermometer for all animals (P < 0.001). The average within-animal variance in maximum temperature for the novel thermometer was numerically higher (P = 0.254) than for the GLA thermometer.

For the second trial in Phase 3, a lack of consistency between repeated measurements with the novel thermometer was observed. Variation between measurements did not follow a discernable pattern and was different for each animal.

For the third trial in Phase 3, large variation still existed from animal to animal regarding the pattern of temperature change, maximum temperature, etc., when using the novel thermometer. There was no discernable pattern regarding positioning of the novel probe within the animal’s rectum, with no single position proving to be ideal compared to the others.

What it means

Although the novel digital thermometer was shown to be faster than the industry standard GLA thermometer at measuring rectal temperatures in cattle, the measurements were not instantaneous, and several concerns related to accuracy, repeatability, and function were identified. Significant variation was observed among animals during Phase 3 regarding how quickly the maximum temperature is reached, how stable these readings are over time, and the pattern of temperature change. There are several factors which might complicate instantaneous temperature measurement, including the presence of air/gas or manure in the rectum. While the novel thermometer showed promise, it requires refinement of the firmware and a better understanding how best to use the technology to capture accurate and repeatable rectal temperatures before it can be ready for commercial production.