Search Results (18)

Dog overpopulation poses serious challenges to public health, animal welfare, and environmental sustainability. While surgical castration remains the most commonly used method for controlling reproduction in dogs, it carries risks and limitations, including surgical complications and long-term behavioral or physiological side effects. This review examines the potential of immunocastration—vaccination targeting gonadotropin-releasing hormone (GnRH)—as an alternative approach. Immunocastration has been shown to suppress reproductive hormones, reduce gonadal function, and decrease behaviors such as roaming, aggression, and sexual mounting in dogs. The review also includes evidence from other species (e.g., pigs, cattle, and horses) to contextualize effectiveness and welfare implications. While behavioral effects are more variable and less frequently studied than physiological outcomes, recent findings suggest immunocastration may have fewer negative emotional side effects (e.g., anxiety and stress-related behaviors) than surgical sterilization. The review highlights the mechanisms, applications, and behavioral outcomes of immunocastration, including its reversibility, cost-effectiveness, and suitability for mass implementation. Overall, immunocastration offers a promising addition to dog population management strategies, particularly in regions with limited surgical infrastructure. Future research should focus on standardizing vaccine protocols and assessing long-term behavioral and welfare outcomes in diverse dog populations. Full article

Surgical castration, a common practice in animal husbandry, raises animal welfare concerns and adversely affects growth performance. Active immunization against gonadotropin-releasing hormone (GnRH) provides a non-surgical alternative. Both methods ultimately suppress sex hormone production, but their comparative effects on the gut microbiota, a crucial regulator of host health and metabolism, remain unclear. Here, 60 Sprague Dawley (SD) rats were randomly allocated into three groups—control (n = 20; 10 female and 10 male), surgical castration (n = 20; 10 female and 10 male), and GnRH immunocastration groups (n = 20; 10 female and 10 male)—at 4–5 weeks of age to comparatively investigate the impacts of surgical versus GnRH immunocastration on the gut microbiota. Our study demonstrated GnRH immunocastration significantly reduced gonadal weight, effectively suppressing gonadal development to a level comparable to surgical castration. However, the two methods induced distinct, sex-dependent shifts in the gut microbiota. Surgical castration reduced the gut microbial community diversity, whereas the community structure of GnRH immunocastrated rats more closely resembled that of the control group, indicating a milder impact on the microbial diversity and composition. Notably, GnRH immunocastration resulted in higher microbial alpha diversity than surgical castration in both female and male SD rats. Specific bacterial genera, such as Clostridia_UCG014, Lactobacillus, and Lachnospiraceae_UCG006, were similarly altered in both surgical castration and GnRH immunocastration female SD rats, while Intestinimonas and Erysipelatoclostridiaceae_UCG004 were concurrently changed in male SD rats. Conversely, Eubacterium_nodatum_group exhibited opposite responses, increasing with GnRH immunocastration but decreasing with surgical castration in male SD rats. Functional prediction revealed fundamental sex differences in microbial metabolic pathways. In females, nitrogen metabolism, glyoxylate/dicarboxylate metabolism, and mismatch repair were changed, while the pathways involved in siderophore biosynthesis, the citrate cycle (TCA cycle), genetic information processing, and amino acid metabolism were changed in male SD rats. In conclusion, GnRH immunocastration appears to be a less disruptive intervention, better preserving microbial diversity and inducing a unique functional profile. These findings highlighted the importance of considering the castration method’s impact on the gut microbial ecosystem in animal production and provided insights for developing humane and effective approaches to animal population control. Full article

Surgical castration of male piglets is a common practice to prevent boar taint and reduce aggressive behaviour. However, it raises welfare concerns and alters carcass fat deposition. Immunocastration, a vaccine-based alternative targeting gonadotropin-releasing hormone (GnRH), mitigates these welfare issues. This study evaluated carcass traits and meat quality in surgically and immunocastrated pigs slaughtered at two weight classes (approximately 116 kg and 136 kg). We compared growth performance, carcass composition, fat quality, and key meat quality indicators among surgically castrated males, immunocastrated males, and immunocastrated females. Inclusion of uncastrated and immunocastrated females provides novel comparative data for mixed-sex production systems, where such information is scarce. This broader evaluation helps fill current gaps in knowledge about immunocastration effects in female pigs. Surgically castrated males showed higher backfat thickness and fat content, particularly at the heavier weight, while immunocastrated pigs exhibited intermediate traits. Ultimate pH, colour, marbling, water-holding capacity, and moisture loss varied with castration method, sex, and slaughter weight, though many differences were subtle. The findings confirm that immunocastration offers a favourable balance between animal welfare and production traits, producing pork quality comparable to surgical castration. These results provide valuable insights for optimizing pork production systems, balancing welfare, efficiency, and meat quality. Full article

Objectives: Research on the immunocastration vaccine is of great significance for animal management. In this study, the gonadotropin-releasing hormone (GnRH) ferritin nanoparticle vaccine was constructed using Spy Catcher-Spy Tag (SC-ST) as a delivery system; Methods: The Spy Catcher was constructed to fuse with the expression vector pET-30a-SF of ferritin nanoparticles. Two polypeptides, STG1: Spy Tag-GnRH I-PADRE and STG2: Spy Tag-GnRH I-GnRH II, coupled to SF in vitro to form two nanoparticles, were designed and synthesized to detect castration effects in mice. We mixed them with the adjuvant MONTANIDE ISA 206 VG to explore the adjuvant’s effect on immunogenicity; Results: All immunized groups produced anti-GnRH specific antibodies after the second immunization, which was significantly higher in the immunized group and the combined adjuvant group than in the control group, and the immune response could still be detected at the 12th week. The concentrations of testosterone, follicle-stimulating hormone, and luteinizing hormone in serum were significantly decreased. The number of sperm in the epididymis of mice in each immune group was significantly reduced, and the rate of sperm deformity was high; Conclusions: The two ferritin-based GnRH nanoparticles developed in this study can significantly cause testicular atrophy, decreased gonadal hormone concentration, decreased sperm count, and increased deformity rate in male mice. These findings provide experimental evidence supporting their potential application in animal immunocastration. Full article

Castration is a prevalent and indispensable practice in sheep husbandry, aiding in enhancing meat quality, mitigating aggressive behavior, and managing unwanted reproduction. Nevertheless, the conventional surgical castration procedure poses several challenges, including heightened stress and pain, detrimental impacts on animal welfare, and diminished economic efficacy in farming operations. Consequently, immunocastration methods, serving as substitutes for surgical castration, are progressively finding application in livestock. The rumen, an essential and distinctive digestive and absorptive organ in ruminants, has been associated with enhanced meat quality and productive performance following castration in previous research studies, albeit fewer investigations have explored the potential impacts of GnRH immunization on the rumen’s internal milieu in sheep post-de-escalation. Hence, the present study delved into evaluating the impact of GnRH immunocastration on the rumen microbiome and metabolomics in male Xizang sheep. This was achieved through the establishment of a GnRH immunocastration animal model and the collection of rumen fluid for microbiological and comprehensive metabolomics investigations. The outcomes of this investigation unveiled that the impact of GnRH immunocastration on body weight gain was more pronounced during the achievement of the castration objective. In addition, the Firmicutes-to-Bacteroidota ratio in the immune male (IM) group exceeded that of the control group (EM), suggesting that GnRH immunodeficiency may enhance the digestion and absorption of feed in male Xizang sheep. At the taxonomic level, the elevated presence of Prevotella and Quinella bacteria in the IM group compared to the EM group indicated that castration influenced a segment of the rumen microbiota in male Xizang sheep, thereby bolstering the digestive and metabolic efficacy of the rumen concerning nutrient utilization, particularly in the breakdown and absorption of proteins, carbohydrates, and lipids, ultimately expediting the fattening process and weight gain in male Xizang sheep following castration. Moreover, analysis of ruminal fluid metabolomics revealed that GnRH immunization had notable impacts on certain metabolites in the ruminal fluid of male Xizang sheep, with metabolites like 5-hydroxyindole acetic acid and 3-hydroxyindole acetic acid showing significant downregulation in the IM group compared to the EM group, while niacin and tyramine exhibited significant upregulation. These findings indicate a profound influence of GnRH immunization on the maintenance of ruminal equilibrium and ruminal health (including the health of ruminal epithelial cells). This study validates that GnRH immunocastration not only achieves the objectives of castration but also enhances ruminal health in male Xizang sheep, thus laying a foundational theoretical basis for the application and dissemination of GnRH immunocastration technology. Full article

Castration is often employed in animal management for reproductive control. However, it is important to evaluate its impact on animal welfare. In this study, we developed rat models for both surgical (n = 6) and GnRH immunocastration (n = 6) to assess the effects of these castration methods on physiological and behavioral characteristics. The novel GnRH-based vaccine significantly increased serum GnRH antibody levels and drastically reduced testosterone, with the testes shrinking to one-fifth the size of those in the control group, thereby halting spermatogenesis at the secondary spermatocyte stage. Behavioral evaluations demonstrated that sexual behavior was significantly suppressed in both surgically and immunologically castrated groups compared to the control, confirming the effectiveness of both methods. However, psychological tests revealed significant signs of depression and social deficits in the surgically castrated group, whereas the behavior of the GnRH-immunocastrated group did not significantly differ from the control. Furthermore, no significant differences in learning and memory were observed among the three groups in the water maze test. Compared to surgical castration, GnRH immunocastration offers effective results and better animal welfare, providing a more humane alternative for livestock management. Full article

Reproductive control in mammals, particularly in beef production systems, is crucial for managing behaviors driven by sex steroids, which can cause biosecurity issues, reduced weight gain, and decreased meat quality. Additionally, controlling sexual activity in females prevents unwanted pregnancies when both sexes are housed together for fattening. Surgical castration in cattle, commonly performed under field conditions, is associated with significant welfare concerns due to pain and infection risks. Furthermore, castrating female cattle in the field is often impractically expensive. Hence, new reproductive control methods that prioritize animal welfare and are suitable for both sexes are essential. Immunocastration (IC), which involves vaccination against the GnRH-I hormone, has emerged as a promising alternative, demonstrating efficacy and safety in various species. Immunocastration has proven to be an effective alternative to surgical castration in controlling reproduction and promoting animal welfare in several species. This study aims to evaluate the safety, immunogenicity, immunocastration effect, and productive impact of a novel IC vaccine developed in Chile for female cattle. Two consecutive trials were conducted, the first under controlled conditions and the second under field conditions. The results demonstrated that the new vaccine is safe and effective for use in beef cattle, inducing specific immunity against GnRH-I, reducing gonadal functionality, and improving productive parameters. These findings suggest that this new IC vaccine can significantly benefit the beef cattle industry by providing a welfare-friendly and efficient method of reproductive control. Full article

Stallion mules have been used as working equids in several countries. Aggressiveness under the influence of testosterone results in the necessity for surgical castration before work training. The gonadotropin-releasing hormone (GnRH) vaccine may be an alternative method for immunocastration in mules. The objective of this study was to evaluate the effect of the GnRH vaccine on anti-GnRH antibody concentration, serum testosterone concentration, clinical adverse effects, and behavioral changes in response to receiving selected physical manipulations from humans. Twenty-five mules were separated into three groups: Control-intact, Control-castrated, and Treatment. The Treatment group was further divided according to condition (intact or unilateral cryptorchid) and age. The Treatment group received 195 µg of the GnRH vaccine intramuscularly at weeks 0, 4, and 8. The anti-GnRH antibody concentrations increased at weeks 6 and 10, and then they gradually decreased to baseline at week 24. The Treatment-intact-young group had the highest concentration of anti-GnRH antibody. The serum testosterone concentrations in the Treatment group were lower than before vaccination from weeks 6 to 14. Subcutaneous edema adjacent to the injection site was detected in the Treatment-intact group after booster vaccination. In conclusion, the mules responded to the GnRH vaccine, which could temporarily suppress testosterone for up to 14 weeks. Full article

The Bísaro pig is a Portuguese autochthonous breed greatly appreciated for its meat quality and is mainly reared outdoors. Immunocastration could be a solution to avoid undesirable pregnancies and boar taint in cull sows. The present study tested three immunocastration protocols (with Improvac^®) according to their reproductive cycle. The first inoculation was performed two weeks after farrowing (IM1, n = 5), at the beginning of estrus (IM2, n = 5), and one week after the end of estrus (IM3, n = 5), followed by a second administration four weeks apart. A control group (C, n = 5) was also included in the same housing conditions. The sample collection included the reproductive tract for morphometric evaluation, neck fat for the quantification of boar taint compounds, and a portion of the Longissimus thoracis et lumborum for meat quality trait assessment. The reproductive tracts from intact sows (C) were significantly heavier compared to the immunocastrated groups (p < 0.05) (1.403 kg C to 0.508 kg IM1, 0.590 kg IM2, and 0.599 kg IM3), suggesting the regression of the reproductive tract to nonstimulated conditions due to immunization against GnRH. The IM1 group exhibited significantly smaller reproductive tract measurements compared to group C for most of the evaluated segments (p < 0.05). No marked differences were observed in the meat quality traits. Therefore, immunocastration can be used in culling sows to avoid ovarian activity, and it is not detrimental to pork quality traits. Full article

Immunocastration and rearing of entire males (EMs) are sustainable alternatives to surgical castration. However, these animal carcasses have variable risk of boar taint and should be identified at the slaughter line. We aimed to identify a simple and reliable indicator of androstenone-related boar taint by evaluating pelvic urogenital tract weight as a marker of boar-taint animals at the slaughter line. The pelvic urogenital tract, testes, and accessory sex glands of EMs and immunocastrates (ICs) were collected, dissected, and weighed, before colorimetric measurements of testicular tissue. Additionally, GnRH antibody titers and testosterone, androstenone, and skatole levels were determined. Our results showed that 81.8% of EMs had androstenone levels above the risk threshold (>0.5 µg/g fat; EM/A^high subgroup), whereas in ICs, the C/A^high subgroup with androstenone >0.5 µg/g fat accounted for only 4.3%. Androstenone levels correlated negatively with GnRH antibody titers and positively with testosterone levels and reproductive organ weights. Identification of ICs with androstenone levels above the threshold (IC/A^high subgroup) may be achieved via testes or pelvic urogenital tract weight measurements. However, in EMs, the latter is a more reliable parameter. A principal component analysis based on these variables and hierarchical clustering also distinguished the A^high from the A^low subgroup, irrespective of IC/EM. The findings highlight the possible use of pelvic urogenital tract weight along with testes weight as a simple, reliable, and efficient morphometric indicator for identifying androstenone-positive carcasses of different sex categories. Full article

This study investigated the effects of immunocastration and slaughter age on the carcass yield performance of intensively farmed common eland males. Eighteen male eland (five immunocastrated juveniles, three intact juveniles, five immunocastrated sub-adults, and five intact sub-adults) were finished for four months, after which their carcass, offal, primal cut, and individual muscle yields were determined. Juveniles were ~6 months of age at the start of the experiment, while sub-adults were ~1.5 years old. Primal cuts were dissected to determine the percentage yields of meat, bones (with tendons), separable fat, and trimmings. Immunocastration had no effect on offal or carcass yields. While sub-adults had increased individual muscle yields, juveniles had greater proportionate yields of primal cuts and a greater total high-value: low-value meat ratio. Whilst slaughtering younger male eland could provide additional economic advantages, this should be considered being against changing marketing trends. Full article

Immunocastration relies on the vaccine-mediated stimulation of an immune response to gonadotropin-releasing hormone (GnRH) in order to interrupt spermatogenesis. This approach offers a less painful alternative to traditional castration approaches but the current, commercially available options require multiple doses of vaccine to maintain sterility. Thus, a series of pilot studies were conducted to determine the feasibility of a single-dose immunocastration vaccine implant. These five studies utilized a total of 44 Holstein bulls to determine the optimal vaccine composition and validate the ability of a stainless-steel subcutaneous implant to deliver a vaccine. Outcome measures included the duration of implant retention, scrotal dimensions and temperature, implant site temperature, anti-GnRH antibodies, and serum testosterone concentration. Over the course of several studies, anti-GnRH antibodies were successfully stimulated by vaccine implants. No significant treatment effects on scrotal dimensions or testosterone were detected over time, but changes in spermatogenesis were detected across treatment groups. Results indicate that a single-dose implantable immunocastration vaccine elicits a humoral immune response and could impact spermatogenesis in bulls. These findings provide opportunities for the refinement of this technology to improve implant retention over longer periods of time. Taken together, this approach will offer producers and veterinarians an alternative to physical castration methods, to improve animal welfare during routine livestock management procedures. Full article

Porker immunocastration against gonadoliberin (GnRH) secretion has been utilized since 2009; however, consumers are still skeptical of it. This is due to not having full information available on the problem of a boar taint, as well as a lack of research on morphological and molecular changes that may occur in the animal reproductive system and other body systems. The present study aimed to explore the functional status of steroidogenic Leydig cells of the testicular interstitial tissue in immunocastrated Polish Landrace pigs. Analyses were performed using Western blot, immunohistochemistry for relaxin (RLN), insulin-like 3 protein (INSL3), pelleted growth factor receptor α (PDGFRα), cytochrome P450scc, 3β- and 17β-hydroxysteroid dehydrogenases (3β-HSD, 17β-HSD), cytochrome P450arom, and 5α-reductase (5α-RED). Immunoassay ELISA was used to measure the androstenone, testosterone, and estradiol levels in the testis and serum of immunocastrates. We revealed disturbances in the distribution and expression of (i) RLN, indicating an inflammatory reaction in the interstitial tissue; (ii) INSL3 and PDGFRα, indicating alterations in the differentiation and function of fetal, perinatal, or adult Leydig cell populations; (iii) P450scc, 3β-HSD, 17β-HSD, P450arom, and 5α-RED, indicating disturbances in the sex steroid hormone production and disturbed functional status of Leydig cells; as well as (iv) decreased levels of androstenone, testosterone, and estradiol in testicular tissue and serum, indicating the dedicated action of Improvac to reduce boar taint at both the hypothalamic–hypophysis–gonadal axis and local level (Leydig cells). In summary, our study provides a significant portion of knowledge on the function of Leydig cells after immunocastration, which is also important for the diagnosis and therapy of testis dysfunction due to GnRH action failure and/or Leydig cell differentiational–functional alterations. Full article

Precocious puberty in beef heifers can result in unwanted pregnancies due to accidental breeding by farm bulls. Inbreeding, premature calving followed by dystocia and a high stillbirth rate or slaughtering of pregnant heifers are the consequences of this behaviour. The aim of the study was to postpone puberty by using Improvac^®, an anti-GnRH vaccine. Therefore, n = 25 calves were twice vaccinated, once at the age of 5 and then at 6.5 months. n = 24 calves served as unvaccinated case controls. The onset of puberty was assigned if progesterone analysis in the blood exceeded 1 ng/mL. Progesterone values were excluded if the corresponding serum cortisol levels were ≥60 nmol/L. Our target was met, as in the vaccinated group none of the calves exceeded a progesterone value >1 ng/mL until the scheduled age of slaughter at 11 months and only 12.5% of the animals exceeded a progesterone value of 1 ng/mL over the whole measuring period (>400 days) compared with 56.5% of the calves in the control group. In conclusion, the favourable results from our study using the vaccine Improvac^® represent an animal-friendly, non-invasive and reliable way to avoid early pregnancy in heifers as well as the slaughter of pregnant cattle. Full article

Castration by surgical techniques is common in livestock; however, post-surgery complications and concerns for animal wellbeing have created a need for new non-invasive alternatives. The objective of this study was to evaluate immunocastration in bulls using antigen GnRX G/Q; a recombinant peptide proved to be effective in laboratory and companion animals. A nine-month trial with 80 9-month-old Normand x Hereford bulls, kept in a pastured system, was conducted. The herd was divided in half with 40 bulls surgically castrated (SC) and 40 castrated by immunization against GnRH (IC). The antigen was injected on days 0 and 40 of the experiment. After the second dose, the IC group had elevated GnRH antibodies and decreased testosterone levels (below 5 ng/mL) that were maintained for 23 weeks. At slaughter on day 190, the immunocastrated group obtained a higher weight, hot carcass, and dressing percentage than the SC group. There was no difference in pH, color of meat, fat coverage, cooking loss, or tenderness between groups. The bulls showed no inflammatory reaction at the injection site or adverse side effects from the vaccine. Our results demonstrate that immunocastration with GnRX G/Q is an efficient and safe alternative to surgical castration in livestock. Additional work evaluating antigen effects over a longer period is needed to validate commercial viability. Full article