Urinary excretion of catecholamines, cortisol and their metabolites in Meishan and large white sows: validation as a non-invasive and integrative assessment of adrenocortical and sympathoadrenal axis activity.

Urinary free corticoids (cortisol and cortisone), catecholamines (norepinephrine or NE, epinephrine or E, dopamine or DA, and their O-methoxylated metabolites) as well as creatinine (Cr) were analysed in 42 spontaneously voided urine samples from Large White (LW, n = 20), Meishan (MS, n = 6), and LW x MS (F1, n = 16) lactating sows. The cortisol concentration in the urine of MS (28.1 pg/micrograms Cr) was five-fold greater than that of LW sows (6.2 pg/micrograms Cr, P < 10(-4)). F1 were intermediate (12.0 pg/micrograms Cr). Mean cortisone concentration was also larger in MS (13.5 pg/micrograms Cr) compared to LW (7.1 pg/micrograms Cr, P < 0.01). Although the differences were less pronounced, the concentrations of the catecholamines were also greater in MS than in LW sows (norepinephrine: 25.4 versus 5.9 pg/micrograms Cr, epinephrine: 8.7 versus 2.8 pg/micrograms Cr and dopamine: 59.2 versus 17.8 pg/micrograms Cr, P < 10(-4)). These results confirmed the hypercortisolism state of MS pigs previously shown by plasma cortisol assay and supported the hypothesis that the sympathetic nervous system is hyperactive in this breed. These urinary investigations may offer possible applications for the assessment of chronic stress.