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

Abstract

Castration of male pigs without anesthesia is a significant welfare issue. Improvac®, a GnRH vaccine induces an endogenous immune response leading to a decrease in testicular steroids. Consequences of different vaccination schemes on testicular function and carcass quality were evaluated in immunocastrated boars (IC), surgical castrates (SC), and entire males (EM). Therefore, 128 male piglets were assigned to five treatment-groups and a long term follow-up group. IC groups received two vaccinations (V1, V2) with Improvac® at 8 and 12, 12 and 16, or 12 and 18 weeks. Testosterone-concentrations decreased significantly two weeks after V2 in feces and dropped in serum from V2 to slaughter (S) except IC-8/12 without differing significantly. GnRH-binding results indicated the highest values for IC-12/18 animals. While IC-12/16 and IC-12/18 animals showed boar taint compounds below the threshold levels, two IC-8/12 animals had concentrations above the threshold level. Feed-efficiency was higher in EM than in SC with IC in between. In IC compared to EM, a decreasing amount of polyunsaturated-fatty-acids was obvious and GnRH-vaccination reduced penile injuries. The examined vaccination protocols reduce penile injuries, improve feed efficiency and carcass quality, and reliably prevents boar taint, if manufacturer’s recommendations concerning vaccination schedules are applied. Therefore immunocastration offers a reliable, animal friendly alternative to surgical castration.

Early Immunocastration of Pigs: From Farming to Meat Quality

“…The contents of fatty acids found in this study are within the ranges found by other authors for immunocastrated pigs [ 16 , 17 , 33 ]. The percentage of MUFA and PUFA in the SF and IMF differed significantly between trial groups, while SFA percentage did not differ significantly.…”

“…Daily weight gain during the complete fattening period did not differ significantly between the trial groups and was 903 and 916 g for the CONTROL and EARLY pigs, respectively. This is in accordance to the values found for immunocastrated organic pigs using the standard immunization scheme [ 16 ] but lower than the values for conventionally kept pigs with an early immunization scheme (8 and 12 weeks of age) [ 17 ]. Although feed intake during the pre-fattening phase did not differ significantly between the trial groups, it was higher in the EARLY pigs.…”

“…They were markedly higher than testes weights of pigs in the early immunization schemes of Sladek et al [ 23 ], which received a first dose at 8 weeks and a second dose 8 or 15 weeks prior to slaughter. 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 ].…”

Recent genetic advances on boar taint reduction as an alternative to castration: a review

“…Other studies in which fatty acid composition was compared among entire males, castrated and immunocastrated have been performed. The results have shown lower abundance of SFA and higher abundance of PUFA in entire males compared to castrated and immunocastrated animals (Pauly et al 2012;Mackay et al 2013;Zoels et al 2020). These studies showed that raising entire males and selecting against boar taint compounds can affect the fatty acid composition of adipose tissue.…”

Endocrine Fertility Parameters—Genomic Background and Their Genetic Relationship to Boar Taint in German Landrace and Large White

“…Nevertheless, the increasing TEST concentration after this age has been described by Colenbrander et al [ 29 ] as a consequence of increasing activity in the testis. Newer studies have shown TEST concentrations in a range of of 0.73 to 3.06 ng/mL in Duroc boars depending on the season [ 30 ] or concentrations of 6.6 ng/mL in a Pietrain × LR cross [ 31 ]. The average TEST concentration of females was 0.49 ± 1.66 in LR and 0.15 ± 0.12 in LW.…”