Return of testicular function after vaccination of boars against GnRH: consequences on testes histology

Abstract

Traditionally, male pigs are surgically castrated without anaesthesia to avoid later occurrence of the sex odour of androstenone in the carcass. Active immunization against gonadotropin-releasing hormone (GnRH) is a painless alternative which inhibits LH and thus steroidogenesis in the Leydig cells. In a preceding study we clarified the return of Leydig cell function after the last dose of antigen by measuring hormones, and found a considerable variation (10 to 24 weeks) till return of their function (testosterone > 0.5 ng/ml blood plasma). The present paper analyses histological data on testes characteristics of the same six boars at an age of 52 weeks (26 weeks after last immunization). Data were compared to another four boars which were not immunized but slaughtered at the same age. Testis weight was related to the concentration of testosterone in blood. In boars, that first returned to testicular function, testis weight even exceeded those in controls probably due to rebound phenomena. Differences in testis weight were mainly due to differences of Leydig cell content of cytoplasm, and less to the size of nuclei. Additionally, the height of seminiferous epithelium was slightly dependent on testosterone concentrations and contributed moderately to differences in testis weight. Altogether, normalization of testicular function, even after return to steroidogenesis, requires another 13 weeks.

Effect of Active Immunization Using Gonadotropin-Releasing Hormone 2-Multiple Antigen Peptide with Different Adjuvants on the Reproductive Functions of Male Rats

“…Moreover, microscopic observation of testicular seminiferous tubules revealed that they had significantly atrophied, and there was almost no mature sperm in the lumens of the ISA 201 adjuvant group compared to the Gel 01 adjuvant and control groups. In the present study, no reversibility appeared uptil the late of this experiment, in contrast to many studies detected testosterone concentration with reversibility (Rottner and Claus, 2009). Based on the contradiction between the results of our study and Rottner's report (Rottner and Claus, 2009) it is thought that the reversibility of the T concentration may occur after a more extended term following immune castration.…”

“…In the present study, no reversibility appeared uptil the late of this experiment, in contrast to many studies detected testosterone concentration with reversibility (Rottner and Claus, 2009). Based on the contradiction between the results of our study and Rottner's report (Rottner and Claus, 2009) it is thought that the reversibility of the T concentration may occur after a more extended term following immune castration. Previous studies reported that the serum LH and FSH levels rapidly increased after GnRH injection, and the LH level quickly reduced after injection of the GnRH antagonist.…”

Influences of Immunocastration on Endocrine Parameters, Growth Performance and Carcass Quality, as Well as on Boar Taint and Penile Injuries

“…Zamaratskaia et al [26] reported inhibitory effects of vaccination against GnRH on male behavior and boar odor that can persist for 22 weeks after V2. In contrast, Claus et al [27] and Rottner and Claus [28] described individual differences in the resumption of testicular steroidogenesis from 10 to 24 weeks after V2. In the present study, fecal testosterone concentration began to increase at least ten weeks after V2.…”

“…For the GnRH antibody increase after V2, individual differences seem to play an important role [4,28,32,33]. Rottner and Claus [28] described maximum GnRH antibody peaks eight to eleven days after V2, whereas Claus et al [33] reported maxima already four to six days after V2. After this peak, GnRH antibody titers start to decrease continuously, explaining lower binding capacity in the early vaccinated groups in comparison to standard vaccinated groups [8].…”

Early Immunocastration of Pigs: From Farming to Meat Quality

“…The individual time span between the last immunization and slaughter in this study was 12 to 23 weeks for the EARLY group pigs and a resumption of steroidogenesis, which is accompanied by a rise of testosterone values, might be an explanation for higher testes weights [ 17 ]. Highly individual and variable time spans of 10 to 24 weeks from the last immunization to a resumption of testes function have been described earlier [ 24 , 25 ]. In these studies, the determined testosterone threshold in the serum for an assumed resumption of the testicular function was 0.5 ng/mL and therefore distinctly lower than values found for the EARLY group pigs in this study.…”