[Active immunization of male pigs against gonadoliberin: effect on the secretion of gonadotropic hormones and on 5 alpha-androst-16-ene-one levels in adipose tissue]

27 boars aged 100 days were allocated to 3 experimental groups. The control group was untreated. The 2 other groups were given injections of LHRH, bound to BSA, with either Freund complete adjuvant or alumina gel. 4 immunisations were achieved at weekly intervals and a fifth injection was performed after 4 weeks. In animals treated with alumina gel, no specific antibodies were obtained. In the other hand, all 9 boars treated with FCA exhibited significant titers of specific anti-LHRH antibodies. In these animals, the neutralisation of blood LHRH induced a significant decline in both LH and FSH concentrations. Consequently, fat androstenone levels dropped dramatically, down to low levels, similar to those observed in surgically castrated males.