Effects of sexual hormones on the adrenocortical axis

Effects of sexual hormones on the adrenocortical axis in pigs A Prunier, C Leclercq, E Merlot UMR SENAH, 35590 Saint-Gilles, France ALIMENTATION AGRICULTURE ENVIRONNEMENT

Introduction ü Surgical castration of male pigs criticized for welfare reasons, stooped in 2018 ü Two available alternative solutions: rearing entire pigs or immunocastrated pigs (Gn. RH inhibition) ü Check for potential effects on health or welfare ALIMENTATION AGRICULTURE ENVIRONNEMENT

Introduction Literature suggests that: ümales sexual hormones inhibit the adrenal axis ümales sexual hormones influence the immune system (inhibition of thymus development and inflammatory reactions) üGn. RH stimulates the adrenal activity Very few data in pigs ALIMENTATION AGRICULTURE ENVIRONNEMENT

Introduction French experimental project supported by ANR (French National Agency for Research) to determine the influence of male sexual hormones on : ü Adrenal and sympathetic axes Present data ü Immune system ü Behaviour ü Growth and nutritional regulations ALIMENTATION AGRICULTURE ENVIRONNEMENT

Material and methods 5 experimental groups : ü Entire males, n = 18 ü Castrated males, n = 14 ü Entire males Vaccinated against Gn. RH, n = 21 but 2 excluded due to lack of sexual regression ü Castrated males Vaccinated against Gn. RH, n = 15 ü Females, n = 15 C-V vs C : evaluate the role of Gn. RH suppression independently of sexual hormones ALIMENTATION AGRICULTURE ENVIRONNEMENT

Material and methods C & C-V: surgical castration at 5 -6 days E-V & C-V: 1 st vaccination against Gn. RH (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 ALIMENTATION AGRICULTURE ENVIRONNEMENT

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 ALIMENTATION AGRICULTURE ENVIRONNEMENT

Results: sexual development Plasma testosterone: effect of castration at 88 & 117 days, effect of castration and vaccination against Gn. RH at 151 days, F = C at 151 days b b aa Comparisons within age, different letters: P < 0. 05 ALIMENTATION AGRICULTURE ENVIRONNEMENT

Results: sexual development Plasma oestradiol: very low levels in all group at 88 & 117 days, effect of castration and vaccination against Gn. RH at 151 days, F = C at 151 days Different letters: P < 0. 05 ALIMENTATION AGRICULTURE ENVIRONNEMENT

Results: sexual development Testes at slaughter: significant regression in E-V males (non-responding pigs were excluded) Different letters: P < 0. 05 ALIMENTATION AGRICULTURE ENVIRONNEMENT

Results: adrenal axis Salivary cortisol at 116 days of age Treatment effect depends on time Significant at 23: 00 Diurnal variation in C & E pigs only Overall: vaccination increases cortisol in castrate pigs only ALIMENTATION AGRICULTURE ENVIRONNEMENT

Results: adrenal axis Saliv. cort. (rsquare), ng/ml Salivary cortisol at 147 days of age Overall: Treatment effect does not depend on time E males have Diurnal variation in all groups lowest levels 2. 2 C 2. 0 C-V E E-V F 1. 8 1. 6 1. 4 1. 2 1. 0 0. 8 9 11 17 23 5 Time of the day, hours 9 ALIMENTATION AGRICULTURE ENVIRONNEMENT

Results: adrenal axis Salivary cortisol at transfer to slaughter house (152 days) Time effect similar in all groups Increase at + 60 min Overall: No treatment effect 2. 0 1. 9 1. 8 1. 7 1. 6 1. 5 C C-V E E-V Different letters: P = 0. 05 ALIMENTATION AGRICULTURE ENVIRONNEMENT

Results: adrenal axis Plasma cortisol, log, ng/ml No significant treatment effect C C-V E E-V F 2. 0 1. 5 1. 0 0. 5 0. 0 88 117 Age, days 151 ALIMENTATION AGRICULTURE ENVIRONNEMENT

Results: adrenal axis Plasma ACTH No clear treatment effect Different letters: P < 0. 08 ALIMENTATION AGRICULTURE ENVIRONNEMENT

Results: adrenal axis Development of adrenals at slaughter (152 days of age) Adrenal development reduced in E males, intermediate in C-V and E-V males (lack of Gn. RH ? ) Within side, different letters: P < 0. 05 ALIMENTATION AGRICULTURE ENVIRONNEMENT

Conclusion ü Vaccination against Gn. RH 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 Gn. RH support (-) ü Adrenal activity seems to be reduced in entire males at around 5 months of age when sexual hormones are high (puberty clearly established) ü Females are closer to Castrate than to Entire males (at about 5 months of age) ü ALIMENTATION AGRICULTURE ENVIRONNEMENT

New questions What are the consequences of the reduced activity of the adrenal of entire male pigs on: ü Their immune system (data showing higher development of the thymus) ü Their ability to cope to stress (e. g. mobilization of metabolic resources) ü Their ability to respond to an immune challenge What about immunocastred males ? ALIMENTATION AGRICULTURE ENVIRONNEMENT

Thanks for your attention! ALIMENTATION AGRICULTURE ENVIRONNEMENT