The use of implanted biotelemetry sensors for measuring poultry deep body temperature responses to ambient
temperatures was investigated. The measurement procedure was validated in a two part study. In the first part, the
ambient temperature was held constant and measurements of deep body temperature were collected over 24 h periods to
detect diurnal rhythms. In the second part, ambient temperature was increased above normal growing conditions and
deep body temperature responses to these increases were recorded. The telemetry measurement system was successful in
detecting deep body temperature variations due to the diurnal rhythm and increases in ambient temperature. These results
are promising for future use of biotelemetric measurements of deep body temperature as early indicators of heat stress.