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The validity of collecting multiple saliva samples for the measurement of cortisol was tested in two sampling regimes in two weight classes of grower pigs (50 and 100 kg). The sampling regimes were a high-frequency, short-duration (HFSD) protocol involving collection of multiple samples within approximately 2 min of each other over a period 30 min. The second regime was a low-frequency, long-duration (LFLD) protocol in which samples were collected every 30 min for 3 h. Both sampling regimes were applied to individually housed pigs. The effect of repeated sampling of a focal pig on its cohorts in a group-housed pen was tested using the LFLD regime.
There was no evidence of an effect of either of the sampling protocols on salivary cortisol concentrations in individually housed or group-housed pigs. There was some evidence that higher concentrations of salivary cortisol were associated with longer individual sampling durations in the HFSD regime for animals in the 50-kg weight class but not in the 100-kg weight class.
The evidence from these experiments indicates that the collection of multiple saliva samples does not affect salivary cortisol concentrations in grower pigs, but that collection of individual samples in as short a time as possible would be prudent to avoid sampling effects in younger animals.
Cook, N. J., Hayne, S. M., Rioja-Lang, F. C., Schaefer, A. L. and Gonyou, H. W. 2013. The collection of multiple saliva samples from pigs and the effect on adrenocortical activity. Can. J. Anim. Sci. 93: 329–333, 10.4141/cjas2012-120.