A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Effects of sexual hormones on the adrenocortical axis in pigs A Prunier, C Leclercq, E Merlot UMR SENAH, Saint-Gilles, France

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Introduction Surgical castration of male pigs criticized for welfare reasons, stooped in 2018 Two available alternative solutions: rearing entire pigs or immunocastrated pigs (GnRH inhibition) Check for potential effects on health or welfare

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Introduction Literature suggests that: males sexual hormones inhibit the adrenal axis males sexual hormones influence the immune system (inhibition of thymus development and inflammatory reactions) GnRH stimulates the adrenal activity Very few data in pigs

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Introduction French experimental project supported by ANR (French National Agency for Research) to determine the influence of male sexual hormones on : Adrenal and sympathetic axes Immune system Behaviour Growth and nutritional regulations Present data

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Material and methods 5 experimental groups : Entire males, n = 18 Castrated males, n = 14 Entire males Vaccinated against GnRH, n = 21 but 2 excluded due to lack of sexual regression Castrated males Vaccinated against GnRH, n = 15 Females, n = 15 C-V vs C : evaluate the role of GnRH suppression independently of sexual hormones

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Material and methods C & C-V: surgical castration at 5-6 days E-V & C-V: 1 st vaccination against GnRH (Improvac®) at 88 ± 1 days, 2 nd vaccination 4 weeks later Blood samples at 88, 116 days (just before 1 st and 2 nd vaccination, all – F), 151 days (all) for testosterone, oestradiol, cortisol, ACTH

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Material and methods Salivary samples at 112 (all – F), 147 days (all), 151 days (response to stress, all –F) for cortisol Slaughter at 152 day: adrenal and testes weight after trimming

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Results: sexual development Plasma testosterone: effect of castration at 88 & 117 days, effect of castration and vaccination against GnRH at 151 days, F = C at 151 days aa bb Comparisons within age, different letters: P < 0.05

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Results: sexual development Plasma oestradiol: very low levels in all group at 88 & 117 days, effect of castration and vaccination against GnRH at 151 days, F = C at 151 days Different letters: P < 0.05

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Results: sexual development Testes at slaughter: significant regression in E-V males (non-responding pigs were excluded) Different letters: P < 0.05

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Results: adrenal axis Treatment effect depends on time Significant at 23:00 Diurnal variation in C & E pigs only Overall: vaccination increases cortisol in castrate pigs only Salivary cortisol at 116 days of age

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Results: adrenal axis Treatment effect does not depend on time Diurnal variation in all groups Overall: E males have lowest levels Salivary cortisol at 147 days of age

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Results: adrenal axis Time effect similar in all groups Increase at + 60 min Overall: No treatment effect Salivary cortisol at transfer to slaughter house (152 days) Different letters: P = 0.05

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Results: adrenal axis No significant treatment effect Plasma cortisol

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Results: adrenal axis No clear treatment effect Plasma ACTH Different letters: P < 0.08

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Results: adrenal axis Adrenal development reduced in E males, intermediate in C-V and E-V males (lack of GnRH ?) Development of adrenals at slaughter (152 days of age) Within side, different letters: P < 0.05

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Conclusion Vaccination against GnRH seems to influence the adrenal axis but effects depend on age and parameter. This may be explained by the existence of various actions: suppression of sexual hormones (+), inflammatory response to the vaccination (+), suppression of GnRH support (-) Adrenal activity seems to be reduced in entire males at around 5 months of age when sexual hormones are high (puberty clearly established) Females are closer to Castrate than to Entire males (at about 5 months of age)

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T New questions What are the consequences of the reduced activity of the adrenal of entire male pigs on: Their immune system (data showing higher development of the thymus) Their ability to cope to stress (e.g. mobilization of metabolic resources) Their ability to respond to an immune challenge What about immunocastred males ?

A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T Thanks for your attention!