Evaluation of production performance and carcass quality characteristics of boars immunised against gonadotropin-releasing hormone (GnRH) compared with physically castrated male, entire male and female pigs

Abstract

The objectives of this study were to assess the performance and carcass quality characteristics of boars immunised against gonadotropin-releasing hormone GnRH (IM) compared with physically castrated males (PM), entire males (EM) and entire female pigs (EF). For the study 288 crossbred (Large White × Landrace) pigs were used comprising four equal groups of 72 IM, 72 PM, 72 EM and 72 EF. The study period was from 74 days of age (31.2 ± 5.57 kg body weight; mean ± std. dev.) to slaughter at 172 days of age (107.7 ± 14.82 kg body weight). PM were physically castrated at 5 days of age and IM pigs were vaccinated with the GnRH vaccine Improvac ® (Pfizer Animal Health) at 74 and 145 days of age (89.1 ± 15.93 kg body weight). Across the duration of the study period, growth rate was numerically highest in IM group and significantly higher than EF (P < 0.01). This was also reflected in respective slaughter weights. EM had the lowest feed:gain ratio (P < 0.001) followed by IM which had a lower ratio than both PM and EF. At slaughter, testes weights were reduced in IM by approximately 55% (P < 0.001) compared with EM. Fat content (backfat thickness and intramuscular fat) was higher and lean percentage of carcass lower in PM compared to all other groups (P < 0.05), with no differences between EF, EM and IM. Boar taint compounds, skatole and androstenone, were lower in IM pigs compared with EM (P < 0.05), and not differing from the concentrations measured in PM and EF. Immunisation of entire male pigs against GnRH allows improved feed efficiency compared with physical castrates with no detriment to carcass or meat quality.Additional key words: boar taint, carcass quality, GnRH immunization, production performance, swine. Resumen Evaluación de los rendimientos productivos y de las características de la calidad de la canal de cerdos machos inmunizados frente a la hormona liberadora de gonadotropina (GnRH) en comparación con machos castrados quirúrgicamente, machos enteros y hembrasLos objetivos del presente estudio fueron evaluar la productividad y características de la calidad de la canal de cerdos inmunizados frente a GnRH (IM) en comparación con machos castrados físicamente (PM), machos enteros (EM) y hembras (EF). Se utilizaron un total de 288 híbridos comerciales (Large White × Landrace). Los PM fueron castrados a los 5 días de vida, mientras que los cerdos IM se vacunaron con GnRH Improvac ® (Pfizer Animal Health) a los 74 (31,2 ± 5,57 kg peso vivo; media ± desv. est.) y 145 días de edad (89,1 ± 15,93 kg peso vivo). La ganancia de peso diaria fue numéricamente mayor en el grupo IM, y de forma significativa frente a las EF (P < 0,01). Este efecto también se reflejó en los pesos de sacrificio. EM mostraron el menor valor de índice de conversión (P < 0,001) seguidos por IM, que mostraron un menor índice que PM y EF. En el sacrificio, el peso testicular se redujo en IM un 55% (P < 0,001) en comparación con EM. El contenido de grasa (espesor de grasa dorsal y grasa intramuscular) fue mayor y el porcentaje magro de la c...

Field experience with surgical castration with anaesthesia, analgesia, immunocastration and production of entire male pigs: performance, carcass traits and boar taint prevalence

“…Both studies confirm that (immuno)castration effectively reduces boar taint, which is in line with the literature (Morales et al, 2010;Batorek et al, 2012a). Interestingly, EM from a similar genotype (Pietrain crosses) showed 0% strong boar taint on some farms and 10% and more on other farms.…”

“…The results of both trials also confirm the existing knowledge on lean meat percentage, with lowest values for SCM, highest for EM and intermediate for IM Morales et al, 2010;Boler et al, 2012;Furnols et al, 2012;Pauly et al, 2012). The effect on carcass conformation is less reported.…”

“…Both trials confirm the better G : F ratio in ad libitum fed EM and IM in comparison with SCM (Dunshea et al, 2001;Morales et al, 2010;Batorek et al, 2012b). This is a result of lower feed intake without clear differences in ADG.…”

“…For IM, results for DG for the overall fattening period differed between studies (Millet et al, 2011). Some studies did not show significant differences in ADG (D'Souza and Mullan, 2003;Morales et al, 2010), whereas others found a higher ADG for IM when fed ad libitum compared with EM, due to the increased ADG after the second vaccination Batorek et al, 2012b;Furnols et al, 2012). Whether or not a difference over the entire fattening period is observed probably depends on the magnitude of the feed intake response after the second vaccination and the time between the second vaccination and slaughter.…”

Influence of sex and immunocastration on feed intake behavior, skatole and indole concentrations in adipose tissue of pigs

“…Immunological castration is achieved by two injections of that specific vaccine in a 4 week interval leading to androstenone levels in adipose tissue as otherwise observed in castrated males (Dunshea et al, 2001;Bauer et al, 2008;Zamaratskaia et al, 2008a). A similar effect on skatole formation has been described (Dunshea et al, 2001;Zamaratskaia et al, 2008a;Morales et al, 2010), even if the synthesis of this tryptophan metabolite occurs in the intestine due to microbial activity .…”