Relationship between plasma, saliva, urinary and faecal cortisol levels in pigs

Abstract

Blood collection for assessment of stress markers such as cortisol, involves restraining and induction of stress on animals. The present study examined the relationship between circulating cortisol levels with its levels in other biological sources (saliva, urine, faeces) to assess utility of non-invasive methods of sample collection for stress assessment in crossbred pigs (Hampshire × Ghungroo). Urine samples were collected after 1 and 2 h of blood and saliva collection, whereas faecal samples were collected after 24 and 48 h of initial sample collection. Mean cortisol levels in plasma and saliva was positively correlated. The correlation between plasma cortisol and second hour mean urinary cortisol values was higher compared to first hour samples. The faecal reactive metabolite levels were weakly correlated to plasma, saliva and urinary cortisol levels. It is concluded that the salivary cortisol values reflect its plasma levels at the time of collection most closely amongst the biological samples studied.