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José Wavreille presents Poster 53 during the poster sessions in the Aula.
Session theme 5: Development and improvement of welfare assessment protocols
125
Poster 53
MEASUREMENT OF REPEATABILITY OF SALIVARY CORTISOL IN
GROUPS OF PREGNANT SOWS
J. Wavreille 1 , V. Planchon 1 , G. Breteau 2 , V. Remience 3 , J. Sulon 3 , N. Bartiaux-Thill 1
1 Animal production and Nutrition Department, Walloon Agricultural Research Centre, Gembloux, Belgium
2 National Veterinary College of Toulouse, Toulouse, France
3 Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium
Whereas the repeatability of salivary cortisol measurement has been established in the laboratory,
pre-analytical factors such as the sampling method, operator, animal and time, may account for the
variability of the results. It is therefore considered important to test the salivary cortisol sampling
methodology for use as a suitable stress assessment indicator in sows.
Repeatability and reproducibility are estimated on the basis of standard ISO 5725-2:1994.
According to that standard, the Cochran and Grubbs tests have to be run firstly to detect and
exclude outliers. The standard deviations of repeatability and internal reproducibility are then
obtained from estimation of variance components of the model studied (S.A.S. version 9.1.3.);
repeatability and reproducibility are then calculated from the respective standard deviations. The
experimental design planned to determine repeatability and reproducibility consists of two operators
taking samples twice in succession from ten sows housed in two groups. Sampling was done with
the aid of cotton bud. Half of the sows were 5 or 10 weeks pregnant. Salivary cortisol levels were
determinated in duplicate by a similar direct radioimmunoassay.
The standard deviation of repeatability and the standard deviation of internal reproducibility
estimated are respectively 25.79 ng/100 ml and 27.18 ng/100 ml. The limits of repeatability and
reproducibility are very high: 71.5 ng/100 ml and 75.3 ng/100 ml. When the same operator takes
two samples from the same sow, the maximum range of dispersion around the result can therefore
be 71.5 ng/100 ml in 95% of cases. If two operators take samples from the same sow, the maximum
range of dispersion is 75.3 ng/100 ml.
As reproducibility and repeatability are very similar, it means that the variability of the
measurements is due to the sows and not to the effects of operators. Two operators can then take
samples equally during experimental trials.
Contact information: José Wavreille or email wavreille@cra.wallonie.be
Complete address: Animal production and Nutrition Department, Walloon Agricultural Research
Centre, 8, rue de Liroux - 5030 Gembloux, Belgium
Species: Pig