Physiological variation in New Zealand jersey cows during summer

Abstract

Six mature Jersey cows were used in field studies of diurnal variation in rectal temperature, pulse rate, and respiration rate used as indicators of the physiological status of an animal. The studies were made during the New Zealand summer.

Repeatability estimates were derived for each of the measurement systems as follows:

1.	1. Pulse rate—O.75.
2.	2. Respiration rate—O.91.
3.	3. Rectal temperature—O.92.

There was a distinct diurnal pattern for each variable, taking the form of a peak around midday and a low point in the early morning. The ranges for each of the variables were not outside the normal range as defined except for some thermal polypnea. Air temperature ranged from 56.0–79.8°F during the experiments.

It is suggested that any thermal stress on the New Zealand Jersey cow during summer is not likely to be of great economic importance.