Vaccination of boars with a GnRH vaccine (Improvac) eliminates boar taint and increases growth performance.

Abstract

Peri- and postpubertal boars accumulate substances (e.g., androstenone and skatole) in their fatty tissue that are responsible for boar taint in pork. The objective of this study was to assess the efficacy of a GnRH vaccine, Improvac, in eliminating boar taint. Three hundred male (200 intact boars, 100 barrows) crossbred (Large White x Landrace) pigs were used in a 2 x 3 factorially arranged experiment. The respective factors were sex group (barrows, boars treated with placebo, or boars treated with Improvac) and slaughter age (23 or 26 wk). Vaccines were administered 8 and 4 wk before slaughter. All Improvac-treated pigs exhibited anti-GnRH titers. Testes and bulbo-urethral gland weights in treated pigs were reduced by approximately 50% (P < 0.001) and serum testosterone levels were below 2 ng/mL in the majority of treated boars (94 and 92% across both age groups at 2 and 4 wk, respectively). Boar taint, as assessed by the concentration of androstenone and skatole in s.c. fat, was suppressed to low or undetectable levels in 100% of Improvac-treated boars. No Improvac-treated pigs had significant concentrations of either androstenone (> 1.0 microg/g) or skatole (> 0.20 microg/g). In contrast, 49.5% of placebo-treated controls had significant androstenone and 10.8% had significant skatole levels, resulting in 10% of the control boars with high concentrations of both compounds. The mean concentrations of taint compounds in the Improvac-treated pigs were not significantly different from those in barrows. Improvac-treated boars grew more rapidly (P = 0.051 and < 0.001 for pigs slaughtered at 23 and 26 wk of age, respectively) than control boars over the 4 wk after the secondary vaccination, possibly because of reduced sexual and aggressive activities. Compared with barrows, Improvac-treated boars were leaner and had superior feed conversion efficiency. The vaccine was well tolerated by the pigs, and no observable site reactions could be detected at the time of slaughter. Vaccination of boars with Improvac allows production of heavy boars with improved meat quality through prevention and control of boar taint.

Performances, meat quality and boar taint of castrates and entire male pigs fed a standard and a raw potato starch-enriched diet

“…In fact EM and EM1 gained on average less than C (ADG: 254 g/day), but were still more efficient (FCR: 20.26 kg/kg). These findings are in line with recent studies reporting a tendency towards lower ADG for entire males reared in group compared to castrates (Dunshea et al, 2001;D'Souza and Mullan, 2002;Suster et al, 2006). Contrarily, some previous studies reported that entire male pigs had higher ADG and better FCR than castrates (Whittemore et al, 1988;Campbell et al, 1989;Dunshea et al, 1993).…”

“…However, compared to recent experiments, these studies with entire males of the nineties were carried out with individually penned pigs, which limited the social interactions and, thus, lowered the energy expenditure on activities unrelated to growth. Carcass yield and carcass fat deposition were lower in EM and EM1 than in C, which confirms the results reported by Sather et al (1999), Dunshea et al (2001) and Zeng et al (2002). It is well known that lower backfat deposition rate affects lipid composition of the adipose tissue as the degree of unsaturation of the lipids increases (Bee et al, 2002).…”

“…However, responses of anabolic steroids production by entire males are inconsistent because performance differences between entire males and castrates depend on genotype and housing conditions. The available results on growth performance are based on older genotypes and also on individually penned animals and, -E-mail: Giuseppe.Bee@alp.admin.ch therefore, might not fully reflect the present situation under commercial conditions (Dunshea et al, 2001;Suster et al, 2006). Compared to castrates (Cronin et al, 2003) and gilts (Rydhmer et al, 2006), entire males are more aggressive and sexually active and their fighting and mounting behaviour can result in leg problems and skin damage.…”

Resource efficiency and economic implications of alternatives to surgical castration without anaesthesia

“…Several experiments have been carried out in recent years in order to analyse the advantages of immunocastration by means of Improvac R (Dunshea et al, 2001;Zeng et al, 2002;Cronin et al, 2003;Jaros et al, 2005), or other vaccines ), compared to surgical castration. In all these tests, efficacy of the immunisation was over 97% of the treated pigs and, in most cases, immunised pigs were generally found to have a higher growth rate and better feed efficiency.…”

“…In a study comparing early and late immunocastrated pigs with surgical castrates, with a total of 300 animals (Dunshea et al, 2001), pigs treated with Improvac R at 18 and 22 weeks and slaughtered at the age of 26 weeks showed a daily weight gain that -measured over the last 4 weeks prior to slaughter -was 32% higher than the average of surgically castrated animals (slaughtered at the same age). In the case of the 'early treated' group the difference was lower (17%), but in both age groups the feed conversion rate was better than that of surgical castrates.…”