The assessment of cortisol concentration in hair has been proposed as a minimally-invasive technique capable of furnishing information over medium/long period stress response. The aim of the present work was to assess the reliability of using bristles as a matrix for the assessment of mean cortisol level in swine. To this aim, bristles were collected by shaving the rump region of 30 naturally synchronized sows housed in a commercial breeding farm, over two successive reproductive cycles. Samples were collected at three key physiological phases (before delivery-BD; weaning time-WT; pregnancy diagnosis-PD) during two consecutive reproductive cycles (1 and 2), which naturally developed in different seasons of the year (PD1 occurred in April, BD1 in June, WT1 in July, PD2 in September and BD2 in November). Samples were processed as follows: hair was repeatedly washed in water and isopropanol to remove the external debris. The sample was then dried, pulverized and 60mg were weighed. Methanol was added to the sample, and the vial was incubated overnight for steroid extraction. Methanol was then transferred to another vial, evaporated and stored at -20°C pending cortisol assessment, which was carried out by a validated RIA. Differences in cortisol levels between the sampling points were studied with one-way ANOVA and the post-hoc Duncan multiple range test. Two-way ANOVA was applied to evaluate the effects of reproductive phase and season. PD1 and PD2 values were 20.10±1.95 and 16.29±2.15 pg/mg, respectively and were significantly higher (P<0.001) when compared to values obtained at BD and WT. Mean cortisol value at BD2 was higher (P<0.001) than at BD1 (10.48±0.96 vs. 5.17±0.51 pg/mg). Our results showed a significant effect of the reproductive phase on cortisol level in bristles (P<0.00001), suggesting, in agreement with what has been well described in the literature, a higher activation of the adrenal response during late pregnancy and lactation with respect to early-mid pregnancy. Such a difference could be not only due to physiological hormonal changes, but also to the different housing conditions (single crates vs. group housing). An effect of season was also detected, with the lowest cortisol values being recorded during the hot season (P<0.005). However, further research would be necessary to investigate if this reduction in cortisol levels during the hot season plays a role in swine seasonal infertility. Our data suggest that cortisol from hair could be regarded as a reliable method for gathering information, otherwise very difficult to collect, on the mean cortisol concentration of pigs over a medium/long period of time.
Study on hair cortisol variations during two successive reproductive cycles in sows
NANNONI, ELEONORA;GOVONI, NADIA;SCORRANO, FABRIZIO;ZANNONI, AUGUSTA;FORNI, MONICA;MARTELLI, GIOVANNA;SARDI, LUCA;BACCI, MARIA LAURA
2014
Abstract
The assessment of cortisol concentration in hair has been proposed as a minimally-invasive technique capable of furnishing information over medium/long period stress response. The aim of the present work was to assess the reliability of using bristles as a matrix for the assessment of mean cortisol level in swine. To this aim, bristles were collected by shaving the rump region of 30 naturally synchronized sows housed in a commercial breeding farm, over two successive reproductive cycles. Samples were collected at three key physiological phases (before delivery-BD; weaning time-WT; pregnancy diagnosis-PD) during two consecutive reproductive cycles (1 and 2), which naturally developed in different seasons of the year (PD1 occurred in April, BD1 in June, WT1 in July, PD2 in September and BD2 in November). Samples were processed as follows: hair was repeatedly washed in water and isopropanol to remove the external debris. The sample was then dried, pulverized and 60mg were weighed. Methanol was added to the sample, and the vial was incubated overnight for steroid extraction. Methanol was then transferred to another vial, evaporated and stored at -20°C pending cortisol assessment, which was carried out by a validated RIA. Differences in cortisol levels between the sampling points were studied with one-way ANOVA and the post-hoc Duncan multiple range test. Two-way ANOVA was applied to evaluate the effects of reproductive phase and season. PD1 and PD2 values were 20.10±1.95 and 16.29±2.15 pg/mg, respectively and were significantly higher (P<0.001) when compared to values obtained at BD and WT. Mean cortisol value at BD2 was higher (P<0.001) than at BD1 (10.48±0.96 vs. 5.17±0.51 pg/mg). Our results showed a significant effect of the reproductive phase on cortisol level in bristles (P<0.00001), suggesting, in agreement with what has been well described in the literature, a higher activation of the adrenal response during late pregnancy and lactation with respect to early-mid pregnancy. Such a difference could be not only due to physiological hormonal changes, but also to the different housing conditions (single crates vs. group housing). An effect of season was also detected, with the lowest cortisol values being recorded during the hot season (P<0.005). However, further research would be necessary to investigate if this reduction in cortisol levels during the hot season plays a role in swine seasonal infertility. Our data suggest that cortisol from hair could be regarded as a reliable method for gathering information, otherwise very difficult to collect, on the mean cortisol concentration of pigs over a medium/long period of time.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
