Long-Term Immunocastration Protocols Successfully Reduce Testicles’ Size in Bísaro Pigs (original) (raw)
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Animal Reproduction Science, 2011
Gonadotropin-releasing hormone (GnRH) vaccine (Improvac ®) is effective at diminishing boar taint by interfering with testis function. Early pre-pubertal vaccination at and 14 weeks-of-age could be desirable if sufficient and sustained effect could be achieved. Crossbred male pigs (n= 24) were randomly assigned to three groups each with 8 individuals: an unvaccinated control group, one group vaccinated with Improvac ® early at ages 10 and 14 weeks, and a third group vaccinated with Improvac at the standard ages of 16 and 20 weeks. The average age at slaughter was 25 weeks. At slaughter, reductions in testes weight and bulbourethral gland length of vaccinated pigs compared with controls were observed (P<0.001), accompanied by lowerered testosterone concentrations in peripheral blood (P<0.001). The diameter of tubuli seminiferi was affected; being 18% smaller in standard and 38% smaller in early vaccinated males, compared with controls (P<0.01). Leydig cells in vaccinated pigs became pycnotic, and their number decreased in early vaccinated pigs. Spermatogenesis was disrupted, evidenced by spermatocyte loss among standard vaccinated pigs to severe spermatogenic arrest among early vaccinated pigs. This histological picture was reflected in the absence of epididymal spermatozoa in 5 of 8 early vaccinated pigs and a dramatic reduction in the remaining 3 early vaccinated pigs. Among standard vaccinated pigs, 5% of the spermatozoa were morphologically normal (>70% in controls, P<0.01). Early vaccination caused a more severe disruption of testicular structure and function than standard vaccination, thus providing an alternative for immunocastration of male pigs.
Acta Scientiae Veterinariae
Background: Surgical castration of male piglets is frequently performed to prevent development of an unpleasant taste and flavor in meat of mature males, called boar taint. Disadvantages of this method are primarily related to the lower feed efficiency of surgically castrated male pigs, production of less lean meat and more fat on the carcasses than boars, as well as ethical issues associated with the procedure itself. Immunocastration is a method of immunization against gonadotropinreleasing hormone (GnRH) and represents an alternative to avoid boar taint. This study aimed to examine the influence of immunocastration on histological and morphometric parameters of male pig testes.Materials, Methods & Results: A total of 60 crossbred male pigs selected from 30 litters were assigned to two experimental groups: boars (n = 30) and immunocastrated males (n = 30). Two doses (2 mL per dose) of the Improvac® vaccine were given to pigs scheduled for immunocastration. The first injection was ...
Theriogenology, 2009
The objective of this study was to determine the short and long term effects of a gonadotropin-releasing hormone (GnRH) vaccine (Improvac TM Pfizer Ltd.), on sexual maturity, development of the reproductive organs, and the morphology of caudal epididymal spermatozoa in non-castrated male pigs. The pigs were slaughtered 4, 16 or 22 weeks after the second Improvac TM vaccination. A total of 80 crossbred non-castrated male pigs were included in this study comprising two experiments, a short-effect (Experiment 1) and a long-effect (Experiment 2). The first experiment included 56 pigs, 24 of them were maintained as controls and 32 were vaccinated twice, and slaughtered 4 weeks after the second vaccination. The second experiment included 24 pigs, 12 controls and 12 vaccinated twice, and slaughtered either 16 weeks (n = 6) or 22 weeks (n = 6) after the second vaccination. None of the immunized pigs was sexually mature at slaughter, i.e. 4, 16 or 22 weeks after second vaccination. Corresponding results of the control pigs showed that 50% had reached sexual maturity at the age corresponding to 4 weeks after the second vaccination, and 100% at slaughter 16, respectively, 22 weeks after vaccination. At 4, 16 and 22 weeks after second vaccination both testes weight and bulbourethral length were significantly reduced (p < 0.001). The percentages of proximal droplets and abnormal heads were significantly lower in the control pigs than in the immunized pigs at slaughter 4 weeks after vaccination, whereas distal droplets were higher. For the other morphological parameters no significant differences were seen, but all mean values except for acrosome defects were numerically lower in the control pigs compared with the immunized pigs. For pigs slaughtered 16 or 22 weeks after vaccination, the vaccination effect was significant for percentages of proximal droplets, distal droplets, acrosome defects, acrosome abnormality and abnormal heads (p = 0.017-0.001). The immunization clearly disrupted the number and morphology of the interstitial Leydig cells, lasting throughout the study period (4-22 weeks after vaccination). Spermatogenesis was also clearly affected in the immunized pigs, to various degrees, from mild disruption (spermatocyte loss, decrease of the normal number of layers of germ cells) to severe loss of germ cells including tubuli with Sertoli cells-only (complete disappearance of germ cells), also covering the entire study period. The results indicated that the effect of immunization persisted for at least 22 weeks after the second vaccination.
2010
The effect of the immunocastration (vaccination against gonadotropin releasing hormone using Improvac ® vaccine) on growth performance, size of reproductive organs and levels of fat androstenone and skatole was studied in Slovenian pig fatteners. The pigs (50% crosses of Duroc), selected from 35 litters (2 castrates and 3-4 boars per litter) farrowed within two weeks period, were assigned to three experimental groups: boars (n=25), immunocastrated males (n=24) and surgically castrated males (n=25). The vaccinations with Improvac ® were performed at the age of 10 and 19 weeks. The trial started when pigs were 12 weeks old, and lasted until 24 weeks of age, when pigs were slaughtered. During the trial, pigs were lodged individually and their daily feed intake (ad libidum) and weight (at 12, 19 and 24 weeks of age) were recorded. At the slaughter line, the testes and accessory reproductive glands were removed and weighed. Subcutaneous fat samples were taken for the determination of androstenone and skatole concentration. Results on androstenone and skatole showed that the immunisation was 100% successful. The levels of androstenone were below a detection limit of the laboratory method in all pigs. For skatole, the concentrations were at comparably low level in surgically and immunocastrated males, whereas higher levels were observed in boars. Vaccination strongly reduced the weight of testes and accessory reproductive glands. Regarding growth performance, the immunocastrated males showed comparable feed intake, feed efficiency and growth rate as boars in the period from the start of the experiment until the revaccination; thereafter they were closer to the surgical castrates. In the present study, the beneficial impact of the immunocastration on pig productivity and on the reduction of substances responsible for boar taint was confirmed in Slovenian local conditions.
Effect of immunocastration (Improvac®) in fattening pigs II: Carcass traits and meat quality
Slovenian Veterinary Research, 2010
The effect of the immunocastration (vaccination against gonadotropin releasing hormone using Improvac ® vaccine) on growth performance, size of reproductive organs and levels of fat androstenone and skatole was studied in Slovenian pig fatteners. The pigs (50% crosses of Duroc), selected from 35 litters (2 castrates and 3-4 boars per litter) farrowed within two weeks period, were assigned to three experimental groups: boars (n=25), immunocastrated males (n=24) and surgically castrated males (n=25). The vaccinations with Improvac ® were performed at the age of 10 and 19 weeks. The trial started when pigs were 12 weeks old, and lasted until 24 weeks of age, when pigs were slaughtered. During the trial, pigs were lodged individually and their daily feed intake (ad libidum) and weight (at 12, 19 and 24 weeks of age) were recorded. At the slaughter line, the testes and accessory reproductive glands were removed and weighed. Subcutaneous fat samples were taken for the determination of androstenone and skatole concentration. Results on androstenone and skatole showed that the immunisation was 100% successful. The levels of androstenone were below a detection limit of the laboratory method in all pigs. For skatole, the concentrations were at comparably low level in surgically and immunocastrated males, whereas higher levels were observed in boars. Vaccination strongly reduced the weight of testes and accessory reproductive glands. Regarding growth performance, the immunocastrated males showed comparable feed intake, feed efficiency and growth rate as boars in the period from the start of the experiment until the revaccination; thereafter they were closer to the surgical castrates. In the present study, the beneficial impact of the immunocastration on pig productivity and on the reduction of substances responsible for boar taint was confirmed in Slovenian local conditions.
Animal Reproduction Science, 2008
The objective of this study was to evaluate the long-term effect of a gonadotropin-releasing hormone (GnRH) vaccine, Improvac (Pfizer Ltd.), on the levels of GnRH antibodies, testosterone, estrone sulphate (E1S) and androstenone, as well as skatole and indole in male pigs. Additionally, the long-term effect of immunocastration on social and sexual behaviour was studied. Male pigs were assigned to two treatment groups: a treatment group given two doses of Improvac (n = 12) and a control group of entire male pigs (n = 12). The pigs were kept either 16 or 22 weeks after vaccination. Blood samples were collected five or six times; prior to both first and second vaccination, then three or four times during the 16 or 22 week period after second vaccination. Immunocastration significantly reduced levels of testosterone and E1S in plasma, and levels of androstenone in fat (P < 0.001 for all). Skatole and indole levels in plasma and fat were also lower in immunocastrated pigs than in entire male pigs. These effects lasted up to 22 weeks after the second vaccination. Testis weight and bulbourethral gland length were lower in immunocastrated pigs at slaughter and these pigs showed less social, manipulating and aggressive behaviour than entire male pigs. The immunocastrated pigs remained sexually inactive throughout the study. Our study represents a further step in the evaluation of the effectiveness of Improvac as an alternative to surgical castration of entire male
Reproduction in Domestic Animals, 2008
The objective of this study, comprising two trials, was to evaluate the effect of a gonadotropin-releasing hormone (GnRH-vaccine Improvac TM ; Pfizer Ltd) in a sample of the Swedish pig population. The pigs (n ¼ 120) were assigned to three groups: control (entire male pigs), surgical castration and immunization against GnRH. Surgically castrated pigs did not express detectable levels of either testosterone or estrone sulphate (E1S) in plasma, or androstenone in fat and had lower skatole and indole levels in fat than entire male pigs. Immunization significantly reduced testes weight and bulbourethral gland length, plasma levels of the testicular hormones testosterone and E1S, and fat levels of androstenone, skatole and indole. Skatole levels in plasma were significantly lower than in entire male pigs in the second trial, but not in the first due to overall low skatole levels. All immunized pigs and surgically castrated pigs expressed skatole concentrations in fat below the level of 0.2 lg/g, above which meat is regarded as tainted. In contrast, eight entire male pigs exceeded this level. Indole levels in plasma from immunized pigs were lower than those from entire male pigs. Surgical castration caused lower daily weight gain in the suckling period compared with piglets raised intact, whereas in the post-weaning period no difference was observed. Immunization resulted in higher feed intake and daily weight gain after the second injection. The estimated lean meat content was improved in comparison with the castrated pigs, but was lower than for entire male pigs. Dressing percentage was lower in immunized pigs than in surgically castrated and entire male pigs. The frequency of skin damage did not differ between immunized and entire male pigs or between immunized and surgically castrated pigs.
Early vaccination with Improvac®: effects on performance and behaviour of male pigs
animal, 2012
The aim of this study was to investigate the effect of giving a two-dose regimen of gonadotropin-releasing hormone vaccine, Improvac R (Pfizer Ltd), earlier than currently recommended, on performance and behaviour of growing/finishing pigs. Cross-bred male pigs (n 5 192) were randomly allocated, within a litter, into four groups at birth: one group of pigs surgically castrated without anaesthesia before one week of age, a second group of early vaccinated pigs given Improvac at 10 and 14 weeks of age, a third group of standard vaccinated pigs given Improvac at 16 and 20 weeks of age, so that the second vaccination was given 4 to 6 weeks before slaughter as recommended by the manufacturer, and a fourth group of entire male pigs. The experiment started when the pigs were 12 weeks old and lasted until 25 weeks of age, when the pigs were slaughtered. The pigs were fed restrictedly. Daily weight gain and feed conversion during the entire raising period did not differ significantly between groups. Estimated lean meat content of early vaccinated and surgically castrated pigs was lower when compared with entire male pigs, whereas standard vaccinated pigs did not differ from entire males. Dressing percentage was higher in early vaccinated and surgically castrated pigs than in standard vaccinated and entire male pigs, partly because of lower size and weight of reproductive organs. For both groups of vaccinated pigs, both problematic and non-problematic behaviours decreased after their second injection, from the levels of entire males to those of surgically castrated pigs. After the second injection, pigs of both vaccination groups performed no mountings, in contrast with entire male pigs of the same age. Skin lesions at slaughter were fewer and less severe for vaccinated pigs compared with entire male pigs. No difference in income per carcass was observed for surgically castrated or vaccinated pigs. However, for entire male pigs the income was lower, as the payment system in Sweden also takes into consideration the additional cost for boar taint analyses and reduced payment for tainted carcasses. Under our experimental conditions, early vaccination with Improvac can be used as an alternative to the recommended schedule to minimise problematic behaviour with unaffected profitability.
Testes Weight is Not a Reliable Tool for Discriminating Immunocastrates from Entire Males
In view of the criticism regarding the piglet castration as currently practiced, one of the alternatives is the active immunisation against the hypothalamic GnRH hormone referred to as immunocastration. This method is effective in prevention of boar taint in pork and has the advantage of avoiding the pain associated with castration (performed without anaesthesia and analgesia). However, in some rare cases the immunocastration may not be effective and such pigs (so called non-responders) present a risk for boar taint. It is therefore important to have a reliable indicator of the effective immunocastration for the use on the slaughter line. Determination of boar taint substances (androstenone and skatole) is time consuming and expensive, whereas the size of reproductive organs could serve as an indicator of successful immunocastration. Present study provides results for 76 immunocastrates (IC) and 55 entire males (EM) varying in body (or carcass) weight and delay between immunocastrat...