Castration Of Male Pigs Research Articles

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

Simple SummarySurgical castration of male pigs is associated with pain. Improvac®, a GnRH vaccine induces an endogenous immune reaction that leads transiently to a decrease in testicular steroid synthesis after second vaccination. Investigating consequences of different vaccination schemes revealed that GnRH vaccination reliably prevents boar taint, if the manufacturers’ recommendations are applied. It had beneficial effects on animal welfare as it reduced penile injuries. Animals showed improved feed efficiency, leaner carcasses, and lower PUFA (polyunsaturated fatty acids) percentages than surgically castrated animals. Thus, immunocastration offers a reliable and animal friendly alternative to surgical castration.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.

Age at castration (surgical or immunological) impacts carcass characteristics and meat quality of male pigs

In order to accurately estimate body composition at slaughter and to meet specific market targets, the influence of age at time of castration (surgical or immunological) on body composition and boar taint indicators must be determined for male pigs. In all, 48 males were randomly assigned to one of four management regimens: (1) entire male pigs (EM), (2) EM surgically castrated at ~40 kg BW and 10 weeks of age (late castrates; LC), (3) conventional, early surgical castrates (within 4 days of birth; EC) and (4) EM immunized with a gonadotropin-releasing hormone (GnRH) analog (primary dose at 30 kg BW and 8 weeks of age; booster dose at 70 kg and 14 weeks of age; IM). Pigs were fed corn and soybean meal-based diets that were not limiting in essential nutrients. Back fat was sampled on days −3, 8, 18 and 42, relative to administering the booster dose of GnRH analog at day 0, to determine androstenone concentrations (n=8 or 9/group). Fat androstenone concentrations in IM were lower than EM between days 8 and 42 after administering the booster dose (173 v. 863 ng/g, respectively; P<0.01), and were not different from surgically castrated males (EC and LC) after day 18. Slaughter occurred at ~115 kg BW, 42 days (6 weeks) after administering the booster dose for IM, and 10 and 20 weeks after surgical castration for LC and EC, respectively (n=8 or 9/group). At slaughter, live BW, liver weight as a percent of live BW, dissectible bone as a percent of cold carcass side, body protein and water contents and whole-body protein deposition decreased with time after surgical castration (linear; P<0.05), whereas dressing percentage, dissectible fat, probe fat depth and body fat content increased with time after surgical castration (linear; P<0.05). The IM had intermediate dressing percentage and dissected fat to EM and EC, whereas liver weight as a percent of live BW and body protein and lipid contents were not different from EM. Whole-body lipid deposition tended to be greater in IM than in EM between 14 and 20 weeks of age (373 v. 286 g/d; P=0.051). In conclusion, castration of male pigs after 6 weeks of age has a lasting effect on physical and chemical body composition. The relationship between time after castration and body composition may be developed to predict carcass composition and can be used to determine the ideal immunization schedule aimed at specific markets in the future.

Ssc-miR-7134-3p regulates fat accumulation in castrated male pigs by targeting MARK4 gene

Castration of male pigs is a common practice used to reduce boar taint in commercial pork production, but it also significantly results in fat accumulation in carcass. Our previous study revealed a miRNA gene, ssc-miR-7134-3p that was implicated in adipogenesis. However, the relationship between ssc-miR-7134-3p and fat deposition due to castration is unknown. In the present study, we observed that ssc-miR-7134-3p targets the coding sequence (CDS) region of MARK4 based on bioinformatics analysis and dual-luciferase assays. Experiments using silent mutations and sub-cloning showed that ssc-miR-7134-3p binds independently to two adjacent sites in the MARK4 CDS. Subsequently, ssc-miR-7134-3p inhibits MARK4 protein expression in pig fibroblast cells, being consistent with the targeting demonstrated in vitro. We found higher MARK4 protein levels in the back fat of castrated pigs than in intact pigs, providing further evidence that MARK4 is involved in regulation of fat deposition. In addition, one SNP (g.2581A>G) in MARK4 was significantly associated with the back fat trait in Chinese and European pig populations. Taken together, we would conclude that ssc-miR-7134-3p targets the MARK4 gene for fat accumulation in the castrated male pigs.

Boar taint compound levels in back fat versus meat products: Do they correlate?

Surgical castration of male pigs will soon be abandoned, turning a major advantage of this practice, the elimination of boar taint, into the biggest challenge for pig industry when raising intact male pigs becomes common practice. To map the (economical) consequences in relation to boar-taint consumer acceptance, as well as offer a processing strategy for tainted carcasses to stockholders, the current study investigated not only back fat boar taint levels, but additionally generated information on the levels of boar taint compounds recovered after the production of commercially relevant meat products using UHPLC-HRMS laboratory analysis. Our results demonstrate that levels of androstenone, skatole and indole in back fat and meat products tend to correlate strongly, particularly in fatty meat products (generally r>0.80). Concentration values in the edible (lean) meat fraction were significantly lower compared to back fat and fat sampled from fresh or processed meat (p<0.05).

Influence of social mixing and group size on skin lesions and mounting in organic entire male pigs

Alternatives to surgical castration are needed, due to stress and pain caused by castration of male pigs. One alternative is production of entire male pigs. However, changed behaviour of entire males compared with castrated males might adversely affect the welfare of entire males and changes in management procedures and production system might be needed. Elements from the organic pig production system might be beneficial in this aspect. The aim of this article is to investigate the effect of grouping strategy including social mixing and group size on levels of mounting behaviour and skin lesions, hypothesising that procedures that disrupt the social stability (e.g. regrouping) will have a larger negative effect in small groups compared with large groups. Approximately 1600 organic entire male pigs of the breed (Landrace×Yorkshire)×Duroc were reared in parallel in five organic herds, distributed across four batches in a 2×2 factorial design in order to test the influence of social mixing (presence or absence of social mixing at relocation) and group size (15 and 30 animals). Animals were able to socialise with piglets from other litters during the lactation period, and were all mixed across litters at weaning. A second mixing occurred at insertion to fattening pens for pigs being regrouped. Counting of skin lesions (1348 or 1124 pigs) and registration of mounting behaviour (1434 or 1258 pigs) were done on two occasions during the experimental period. No interactive effects were found between social mixing and group size on either skin lesions or mounting frequency. Herd differences were found for both mounting frequency and number of skin lesions. No association between skin lesions and mounting were revealed. Social mixing and group size were shown as interacting effects with herds on mounting frequency (P<0.0001), but with no consistent pattern across all herds. In addition, no effect of social mixing was found on mean number of skin lesions, but more lesions were observed in large groups (P<0.036). This could indicate that keeping entire male pigs in groups of 30 animals as compared with smaller groups of 15 may marginally decrease the welfare of these animals.

Reduction of Boar Taint Compounds in Kraski prsut through Dry-curing Process

Given that surgical castration of male pigs could be abandoned, the problem of product acceptability can become critical in dry-cured hams, especially when raw material comes from conventional pig husbandry. In this study, we have investigated 16 thighs harvested from 8 entire male fatteners that were submitted to 15 months of dry-curing process. Skatole and androstenone were determined in subcutaneous fat before (n = 8) and post processing (n = 16). After 15 months of dry-curing, markedly lower fat tissue concentrations of androstenone (36%) and skatole (20%) were determined. The reduction was independent of the level of boar taint substances.

Neonatal surgical castration of male pigs reduces thymic growth but has moderate consequences on thymocytes1

Thymus integrates numerous signals from the neuroendocrine-immune system, including sex steroids, glucocorticoids, and catecholamines. Neonatal surgical castration, commonly practiced in pig husbandry, modifies thymic hormonal environment, for example, sex steroids and probably glucocorticoids and catecholamines, which are important modulators of thymic function. This study aimed at investigating, in pubescent male pigs, the consequences of neonatal suppression of testicular hormones on thymic T cell differentiation and hormonal control of thymocyte proliferation. A total of 34 male pigs were allocated to 2 experimental groups: control (CT) intact males and males surgically castrated (SC) at 5 or 6 d of age. At slaughter, thymus was weighed and thymic samples were collected to determine fat content and distribution of thymocyte subsets by identification of CD1, CD4, CD8, and γδ T cell receptor (TCR) cell surface markers and to measure thymocyte proliferation in presence of cortisol, norepinephrine, and sex steroids. Results showed that absolute and relative thymus weights were greater (P < 0.01 and P < 0.01, respectively) whereas thymic fat content was less (P < 0.01) in CT than in SC pigs. Surgical castration did not change the frequency of CD1+ immature thymocytes. The proportion of γδ T cells tended to be greater in CT than in SC pigs (P < 0.1) but the proportions of CD4+, CD8+, and CD4+CD8+ thymocytes were similar in both groups (P > 0.1) indicating that the Tαβ lineage was not influenced by early castration. Proliferation of thymocytes in response to concanavalin A (ConA) was greater in SC than in CT pigs (P < 0.05). Cortisol and norepinephrine decreased the ConA-induced proliferation in CT and SC pigs (P < 0.05). In addition, proliferation of thymocytes was less inhibited by norepinephrine in SC than in CT males (P < 0.05). The greatest concentration of testosterone (25 ng/mL) increased (SC males, P < 0.05) or tended to increase (CT males, P < 0.1) the proliferative responsiveness to ConA but the lowest dose (2.5 ng/mL) and the greatest dose of testosterone combined with estradiol had no significant effect (P > 0.1). Overall, our data show little effect of neonatal castration on thymocyte differentiation as well as of sex hormones on thymocyte proliferation. However, thymic cells seem to be more sensitive to the inhibitory influence of norepinephrine in CT than in CS pigs. The significance of such difference for animal health remains to be explored.

A comparison of slaughter performance and meat quality of pigs immunised with a gonadotrophin-releasing factor vaccine against boar taint with physically castrated pigs

The objective of this study was to evaluate the effect of vaccination against gonadotropin-releasing factor (GnRF) on carcass characteristics and meat quality and back fat quality. In total, 400 healthy male pigs were randomly assigned into two treatment groups: physically castrated males (CM) and vaccinated males (IM). CM pigs were physically castrated within 3 days of age. IM pigs received the GnRF vaccine twice, at 14 and 21 weeks of age. At the end of the experiment, 20 pigs of each treatment were weighed individually and slaughtered at 25 weeks of age. The longissimus muscle was collected to evaluate the meat quality including pH, drip loss, shear force, cooking loss, intramuscular fat, fatty acid composition and inosine monophosphate. Subcutaneous fat was sampled to evaluate fatty acid composition. IM pigs had a lower dressing percentage and were leaner (P &lt; 0.01). The inosine monophosphate content was higher in pork from IM pigs than from CM pigs (P &lt; 0.05). IM pigs had a higher content of polyunsaturated fatty acids in longissimus muscles than CM pigs (P &lt; 0.01), mostly because of the higher linoleic acid content (P &lt; 0.01). IM pigs had higher levels of unsaturated fatty acids in subcutaneous fat than CM pigs (P &lt; 0.01), mostly because of the higher linoleic acid and linolenic acid (P &lt; 0.01) and the lower myristic acid content (P &lt; 0.01). There were no adverse effects of the GnRF vaccine on slaughter performance and meat quality of pigs. These results suggest that GnRF vaccine administered to pigs increases the inosine monophosphate content in longissimus muscles and the content of polyunsaturated fatty acids in longissimus muscles and back fat. Consequently, vaccination with Improvac for boar taint control will provide a good alternative to physical castration of male pigs.

New GnRH-like peptide construct to optimize efficient immunocastration of male pigs by immunoneutralization of GnRH

Castration of male pigs is routinely performed in order to prevent the occurrence of boar taint in pig carcasses. However, boar taint can also be eliminated by immunological castration using a synthetic peptide vaccine against GnRH. For pig farming, to make immunocastration a feasible alternative method to surgical castration, the composition of the vaccine has to be not only reliable and effective but also cost-efficient and safe. Previously the authors have developed an effective immunocastration vaccine by replacing the monomer GnRH by a much more immunogenic tandem peptide. However, this tandem-GnRH vaccine preparation needs Complete Freund's adjuvant and to be applied at a relatively high dose. Therefore, alternative antigens were designed to cope with this problem and tested with different adjuvants and dosages. An effective new antigen was designed based on a GnRH-tandem peptide, which was dimerized and modified in one amino acid position of the decapeptide to allow conjugation of this tandem-dimer to ovalbumin. In mild adjuvants and in low dosage, this antigen was very effective in reducing testis weight, serum LH and androstenone level in backfat. Thus, an improved immunocastration vaccine has been designed that is relatively cost-efficient and highly efficacious in two vaccinations at low dose.