Boar Taint Research Articles

Performance and carcass characteristics of immunocastrated and surgically castrated Iberian pigs fed diets of different protein concentration. Preliminary results

espanolLa inmunocastracion ha resultado una estrategia util en el cerdo para prevenir el olor sexual en la carne. En trabajos previos se indica que los cerdos inmunocastrados (IC) pueden presentar mejores indices productivos que los castrados quirurgicamente (SC). Ademas de las ventajas en bienestar animal que conlleva esta practica, la mejora en produccion puede tener interes en razas como la Iberica, con capacidad de crecimiento limitada. El objetivo de este estudio ha sido examinar los efectos de la inmunocastracion sobre los indices productivos del cerdo Iberico, el uso de la proteina en la dieta y las caracteristicas de la canal, en animales alimentados con dietas de diferente concentracion proteica. Se utilizaron 27 animales de tres sexos (machos IC, machos SC, y hembras IC) alimentados con 3 dietas isoenergeticas (160, 140 y 120 g PB/kg materia seca), con tres animales por cada combinacion de tratamientos. Los animales se vacunaron contra la hormona liberadora de gonadotropina a los 4,3 (40 kg) y 6 meses de edad (70-80 kg). Los tratamientos se ofrecieron a los animales, que permanecieron alojados individualmente, desde los 40 a los 100 kg de peso. Se realizaron ensayos de digestibilidad y balance de N a los 50 y 90 kg de peso. A los 100 kg se sacrificaron los animales. Los resultados preliminares indican que los machos IC tuvieron un ritmo de crecimiento superior (803 vs 706 and 696 g/d, para machos IC, machos SC y hembras IC, respectivamente; P EnglishImmunocastration has proved to be an effective strategy to prevent sexual development and boar taint in pigs. Previous results indicate that immunocastrated (IC) pigs exhibit better performance than surgically castrated (SC) pigs. In addition to animal welfare benefits, this fact could be of interest for Iberian pigs, as their growth capacity rapidly diminishes as animal ages. The purpose of this study was to examine the effects of immunocastration on Iberian pig performance, protein utilization, and carcass traits under different dietary protein concentrations. Pure Iberian pigs (n=27) were used as follows: 3 sexes (IC males, IC females, SC males); 3 isoenergetic diets (160, 140 and 120 g CP/kg DM); 3 pigs/ group. Pigs were vaccinated against Gonadotropin Releasing Hormone at 4.3 months (40 kg) and 6 months (70-80 kg) of age. Experimental diets were offered to individually-housed pigs from 40 to 100 kg BW. Digestibility and N-balance assays were performed at 50 and 90 kg BW, respectively. Pigs were slaughtered at 100 kg BW. Preliminary results indicate greater growth rate for IC males (803 vs 706 and 696 g/d, for IC males, SC males and IC females, respectively; P

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.

Immunocontraceptive Vaccine- an Ore to be Mined

Immunocontraception is the novel contraceptive approach, which uses body immune system to elicit an immune response to wedge the important steps in reproduction and reduce the fertility rate in vaccinated animals. Immunocontraceptives are developed mainly to target the three main areas of reproductive process namely gamete production, gamete function, and gamete outcome. Contraceptive vaccines, which antagonize the effect of gonadotropin-releasing hormone (GnRH), follicular stimulating hormone (FSH) and luteinizing hormone (LH) have been tested in various species including dogs and cats. GnRH based vaccines are used for immune-castration of pigs to reduce the boar taint, which devalues the pork. Vaccines acting through the sperm-specific proteins and zona pellucida (ZP) glycoproteins have a greater advantage because of their high specificity to the germ cells. Immunization of dogs with native porcine ZP inhibit the fertility associated with ovarian dysfunction. Production of the monoclonal antibody against these proteins have added the advantage in immunocontraception. Recombinant ZP vaccines produced using Escherichia coli have reduced cross-reactivity with the somatic cells and impart long-term infertility. In spite of these advantages, immunocontraceptives may develop resistance in the immunized population in future, so more scientific inputs are required to increase the immunogenicity of immunocontraceptive vaccines and the novel vaccine delivery methods need to be developed which would impart long-term infertility with a single injection.

Histological and Morphometric Examination of the Testes of Boars and Male Pigs Immunocastrated with Improvac®

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 &amp; 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 given at 10 weeks of age, and the second injection at 20 weeks of age. All pigs were fed the same commercial diet ad libitum, group-housed (15 pigs/pen) and slaughtered at 25 weeks of age. After slaughter, testicle weights were measured and samples of testicular tissue were taken for histological examination. Immunocastrated males had lower testicle weights than boars (P &lt; 0.01). Furthermore, structural damage to the germinal epithelium was visible in the seminiferous tubules of vaccinated pigs. In the testicular interstitium of these animals, the number of Leydig cells were reduced; almost all of these cells exhibited different degrees of abnormality. Moreover, the diameter of the seminiferous tubules and thickness of the germinal epithelium were greater (P &lt; 0.01), and the percentage of germinal epithelium in the seminiferous tubules as well as percentage of blood vessels in the interstitium were higher in boars as compared to immunocastrated males (P &lt; 0.01). Seminiferous tubule lumen diameter was greater (P &lt; 0.01), and percentage of lumen in the seminiferous tubules as well as percentage of non-blood vessel tissue in the interstitium were higher in immunocastrated males than boars (P &lt; 0.01).Discussion: Vaccination against GnRH, as used in this study, reduced the synthesis of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which led to decreased spermatogenesis and androgen production. The smaller diameter of the seminiferous tubules as well as germinal epithelium thickness, and lower percentage of germinal epithelium in the seminiferous tubules in immunocastrated males could be explained by reduced FSH synthesis, and subsequent reduced spermatogenesis. The described testicular malformations in immunocastrated animals caused their lower weight, and greater diameter of the lumen as well as a higher lumen percentage of the seminiferous tubules. The vaccine reduced LH synthesis, so the Leydig cells of immunocastrated animals had lower activity than the same cells in boars. The percentage of blood vessels in the interstitium of boar testes was higher, which was related to the blood supply required for normal function of Leydig cells. It was concluded that differences existed in the structure of the seminiferous tubules and interstitium between boars and immunocastrated males , which were reflected in values of the examined histological and morphometric parameters. The development of these differences was related to the inhibition of GnRH synthesis and secretion.

Use of genetic markers to reduce boar taint in Canadian pigs – Preliminary results from validation in commercial trials

cAMP-responsive element-binding protein (CREB)-regulated transcriptional coactivator 3 (CRTC3) is well known to be related to obesity in humans and mice. However, the effects of CRTC3 have not been studied in pigs. Here, we characterized the structure of the porcine CRTC3 gene and identified single nucleotide polymorphisms (SNPs) in its coding region. Moreover, mRNA expression profiles of CRTC3 in muscle and fat tissues were examined. Of the 40 identified SNPs, the p.V515F mutation, located on exon 16, was genotyped in 368 Yorkshire pigs. The p.V515F mutation was significantly associated with lean meat production ability, including reduced back fat thickness (P = 0.0317) and loin eye area (P = 0.0174). Moreover, the SNP was significantly associated with differences in intermuscular fat (P = 0.0092), total muscle area in the belly (P = 0.0108), and total fat percentage in the belly (P = 0.0298). Taken together, our results suggest that the p.V515F mutation affects to lean meat production ability and amount of belly fat.

Consumer acceptance of minced meat patties from boars in four European countries

A consumer study was performed in four EU countries to further clarify the acceptability of meat with boar taint. In Denmark, France, Italy and Poland, a total of 476 female consumers evaluated 8 meat patties from boars with varying levels of skatole (0.10–0.40μg/g fat tissue) and androstenone (0.47–2.00 μg/g fat tissue), in a pair-wise comparison with patties from castrates. Boar meat patties were always less preferred than the castrate meat patties, regardless of the level of androstenone and skatole. Acceptability of the boar meat patties decreased with increasing skatole level. In samples with low skatole levels, higher levels of androstenone also reduced acceptability among androstenone sensitive consumers. No clear threshold levels for androstenone and skatole could be identified. Maps presenting the reduction in preference due to increasing levels of skatole and androstenone, and corrected for the general acceptance of the meat product were developed, taking into account androstenone sensitivity. Further work is needed, covering the whole range of androstenone and skatole levels found in entire male pigs and for a wider set of meat products.

Eating quality traits of shoulder roast and stir fry cuts outperformed loin and silverside cuts sourced from entire and immunocastrated male pigs

This study investigated the effects of ageing period (2 or 7days), endpoint temperature (70 or 75°C), cut type (loin (M. longissimus thoracis et lumborum), silverside (M. biceps femoris), blade (M. triceps brachii) and chuck tender (M. supraspinatus)), cooking method (roast and stir fry (all cuts) and steak (loin only)) on eating quality attributes of pork from entire and immunocastrated male pigs. Higher intramuscular fat levels were found in all cuts from immunocastrated males compared with entire males. Of the seven cut type×cooking method combinations evaluated, shoulder cuts had the lowest fail rate (P<0.001) and loin steak and silverside cuts scored lowest (P<0.001) for tenderness, juiciness, overall liking, quality grade and re-purchase intention. Although no differences in sensory scores due to gender were observed, boar taint was identified in 10% of entire males. Minimising adverse risks in eating quality due to boar taint in males remains a key industry issue to ensure consistent delivery of high quality pork.

Exploiting whole genome sequence data to fine map and characterize candidate genes within a quantitative trait loci region affecting androstenone on porcine chromosome 5.

SummaryMale piglets are routinely castrated to eliminate boar taint. However, this treatment is undesirable, and alternative approaches, including genetic strategies to reduce boar taint, are demanded. Androstenone is one of the causative agents of boar taint, and a QTL region affecting this pheromone has previously been reported on SSC5: 22.6–24.8 Mb in Duroc. The QTL region is one of the few reported for androstenone that does not simultaneously affect levels of other sex steroids. The main objective of this study was to fine map this QTL. Whole genome sequence data from 23 Norwegian Duroc boars were analyzed to detect new polymorphisms within the QTL region. A subset of 161 SNPs was genotyped in 834 Duroc sires and analyzed for association with androstenone in adipose tissue and testosterone, estrone sulphate and 17β‐estradiol in blood plasma. Our results revealed 100 SNPs significantly associated with androstenone levels in fat (P < 0.001) with 94 of the SNPs being in strong linkage disequilibrium in the region 23.03–24.27 Mb. This haplotype block contains at least four positional candidate genes (HSD17B6,SDR9C7,RDH16 and STAT6) involved in androstenone biosynthesis. No significant associations were found between any of the SNPs and levels of testosterone and estrogens, confirming previous findings. The amount of phenotypic variance explained by single SNPs within the haplotype block was as high as 5.4%. As the SNPs in this region significantly affect levels of androstenone without affecting levels of other sex steroids, they are especially interesting as genetic markers for selection against boar taint.

Lipolysis and aroma generation as mechanisms involved in masking boar taint in sodium reduced fermented sausages inoculated with Debaryomyces hansenii yeast.

The use of boar back fat for processing of fermented sausages may cause the presence of abnormal odours. In dry-cured products, ripening time is essential to develop the sensory characteristics. Yeast has been proposed as an alternative to mask boar taint odour through its metabolic activity but it is necessary to elucidate which mechanisms are involved. The aim is to study the effect of Debaryomyces hansenii inoculation on the lipolysis process and generation of aroma compounds in fermented sausages manufactured with boar back fat at two different ripening times. D. hansenii inoculated sausages had a higher degree of lipolysis as demonstrated by higher content of free fatty acids, ester compounds and branched aldehydes which contribute the fruity odour. The increase in lipolysis produced by D. hansenii inoculation was not followed by an increase in oxidation during processing possibly due to the metabolic activity of yeast. The effect of back fat type was scarcely appreciated whereas ripening time had a stronger effect on sausage. Boar sausages were characterised by a lower polyunsaturated fatty acid profile and lesser lipolysis than gilt sausages. Yeast inoculation with D. hansenii and long ripening time were appropriate strategies to limit the perception of boar taint in dry fermented sausages. © 2017 Society of Chemical Industry.

Fine mapping of a QTL affecting levels of skatole on pig chromosome 7

BackgroundPrevious studies in the Norwegian pig breeds Landrace and Duroc have revealed a QTL for levels of skatole located in the region 74.7–80.5 Mb on SSC7. Skatole is one of the main components causing boar taint, which gives an undesirable smell and taste to the pig meat when heated. Surgical castration of boars is a common practice to reduce the risk of boar taint, however, a selection for boars genetically predisposed for low levels of taint would help eliminating the need for castration and be advantageous for both economic and welfare reasons. In order to identify the causal mutation(s) for the QTL and/or identify genetic markers for selection purposes we performed a fine mapping of the SSC7 skatole QTL region.ResultsA dense set of markers on SSC7 was obtained by whole genome re-sequencing of 24 Norwegian Landrace and 23 Duroc boars. Subsets of 126 and 157 SNPs were used for association analyses in Landrace and Duroc, respectively. Significant single markers associated with skatole spanned a large 4.4 Mb region from 75.9–80.3 Mb in Landrace, with the highest test scores found in a region between the genes NOVA1 and TGM1 (p < 0.001). The same QTL was obtained in Duroc and, although less significant, with associated SNPs spanning a 1.2 Mb region from 78.9–80.1 Mb (p < 0.01). The highest test scores in Duroc were found in genes of the granzyme family (GZMB and GZMH-like) and STXBP6. Haplotypes associated with levels of skatole were identified in Landrace but not in Duroc, and a haplotype block was found to explain 2.3% of the phenotypic variation for skatole. The SNPs in this region were not associated with levels of sex steroids.ConclusionsFine mapping of a QTL for skatole on SSC7 confirmed associations of this region with skatole levels in pigs. The QTL region was narrowed down to 4.4 Mb in Landrace and haplotypes explaining 2.3% of the phenotypic variance for skatole levels were identified. Results confirmed that sex steroids are not affected by this QTL region, making these markers attractive for selection against boar taint.

Differential expression and co-expression gene networks reveal candidate biomarkers of boar taint in non-castrated pigs

Boar taint (BT) is an offensive odour or taste observed in pork from a proportion of non-castrated male pigs. Surgical castration is effective in avoiding BT, but animal welfare issues have created an incentive for alternatives such as genomic selection. In order to find candidate biomarkers, gene expression profiles were analysed from tissues of non-castrated pigs grouped by their genetic merit of BT. Differential expression analysis revealed substantial changes with log-transformed fold changes of liver and testis from −3.39 to 2.96 and −7.51 to 3.53, respectively. Co-expression network analysis revealed one module with a correlation of −0.27 in liver and three modules with correlations of 0.31, −0.44 and −0.49 in testis. Differential expression and co-expression analysis revealed candidate biomarkers with varying biological functions: phase I (COQ3, COX6C, CYP2J2, CYP2B6, ACOX2) and phase II metabolism (GSTO1, GSR, FMO3) of skatole and androstenone in liver to steroidgenesis (HSD17B7, HSD17B8, CYP27A1), regulation of steroidgenesis (STARD10, CYB5R3) and GnRH signalling (MAPK3, MAP2K2, MAP3K2) in testis. Overrepresented pathways included “Ribosome”, “Protein export” and “Oxidative phosphorylation” in liver and “Steroid hormone biosynthesis” and “Gap junction” in testis. Future work should evaluate the biomarkers in large populations to ensure their usefulness in genomic selection programs.

Surgical castration with pain relief affects the health and productive performance of pigs in the suckling period

BackgroundSurgical castration is still practiced in many EU countries to avoid undesirable aggressive behavior and boar taint in male pigs. However, evidence shows that castration is painful and has a detrimental influence on pig health. This study investigated the clinical and productive effects of surgical castration in the suckling period.A total of 3696 male pigs, 3 to 6 days old, comprising of 721 litters from two different farms were included in the study. Within each litter, half of the males were kept as intact males (IM) and half were surgically castrated (CM). Surgical castration was conducted by a trained farmer. Average daily gain (ADG), body weight at weaning (BWW), percentage of pre-weaning mortality (PWM) and antibiotic usage were measured. Pig major acute phase protein (PigMAP) serum concentrations were analyzed prior to castration, and on days 1 and 10 after castration. Productive performance data were analyzed using a linear mixed model. Mortality and percentage of pigs treated with antibiotics were analyzed using the Fisher’s exact test.ResultsNo overall differences in BWW and ADG were observed between the two groups. However, differences were observed when the same effects were analyzed in the 25% lightest, 50% medium and 25% heaviest pigs at birth. PWM was higher in CM than in IM groups (6.3% vs 3.6%; p < 0.001), especially in the light (12.2% vs 6.2%; p = 0.02) and in the medium (5.5% vs 2.7%; p = 0.04) weight groups. In the heaviest pigs group PWM was not affected by castration, but IM tended to show higher ADG (p = 0.06) and showed higher BWW (8.0 kg vs 7.8 kg; p = 0.05) than CM. There were no differences in percentage of pigs treated with antibiotics between the two groups (5.8% vs 5.8%; p = 0.98) in this study. Furthermore, PigMAP was increased in CM the day after castration (0.944 mg/ml vs 0.847 mg/ml; p = 0.025), but there was no difference between CM and IM groups at day 10.ConclusionsSurgical castration has a negative impact on production in the suckling period because it causes an increase in PWM, especially in pigs in the three lower quartiles for body weight, and negatively affects the BWW in pigs born in the highest quartile for body weight.

Attitudes of Serbian food technology students towards surgical and immunocastration of boars and their sensitivity to androstenone and skatole

Various European Union pork chain actors and stakeholders agreed in 2010 on a road map to voluntarily abandon piglet castration by 1 January 2018. Because currently in Serbia, male piglets are surgically castrated and consumers are not used to the boar taint odour and flavour, the introduction of boar meat may modify the acceptability of pork. The objective of the study was to investigate the attitudes, awareness and opinions of future Serbian food technologist towards surgical castration of boars and its alternatives, and to test their sensitivity to androstenone and skatole. We found that they were concerned about the animal welfare issues and that they were willing to pay a little more for meat from animals treated with dignity. This was more so if they were females and less so if they had had a rural upbringing. They strongly believed that surgical castration is painful for the animals, but at the same time agreed that meat from castrated pigs is of better quality. Their ambiguous attitudes regarding efficacy and quality of alternatives to surgical castration clearly indicated the knowledge gap that must be filled by appropriate modifications of the curriculum. Students demonstrated average sensitivity to both androstenone and skatole. Females exhibited higher intensities of difference in both cases.

713 Sensory characteristics of Berkshire crossbreds sired by heritage breeds

The objective of this study was to evaluate the sensory characteristics of Berkshire crossbreds sired by heritage breeds. The experiments were conducted at the North Carolina Agricultural and Technical State University farm located in Greensboro, North Carolina. Berkshire sows were artificially inseminated with semen from Berkshire (BB) and Hereford (HB) boars. Piglets were farrowed outdoors and were housed in a deep-bedded hoop structure after weaning at 4 weeks of age. The boars were not castrated, and the piglets were given standard NRC feed and water ad libitum. Animals were randomly selected and harvested at an USDA inspected abattoir at approximately 200 days of age. Loins were removed from one side of 14 BB and 10 HB pigs after harvest, and were packed in ice and transported to the NCSU Food Science for sensory panel testing. Samples of loin chops from BB and HB female and male pigs were presented to 101 panelists. The panelists evaluated the overall liking, as well as the overall flavor, freshness, texture and meaty flavor likings for each of the four samples on a 9-point hedonic scale where 1 = dislike extremely and 9 = like extremely. They also evaluated the texture, moisture and meaty flavor of the samples on a 5-point JAR scale where 1 or 2 = too little, 3 = just about right, and 4 or 5 = too much. The responses were analyzed with PROC GLM in SAS 9.3. Breed and sex were included as fixed effects. Interaction between breed and sex was not included because it wasn't statistically significant (P > 0.05). The difference between the breeds, as well as the sexes, were not significant for the overall, overall flavor, freshness, and meaty flavor likings (P > 0.05). There was a significant difference between both breeds and sexes for the texture liking (P < 0.05). Berkshire sired pigs and females scored higher than HB and males, respectively. However, when the panelists were asked to evaluate the texture of the loin chops on a 5-point JAR scale, they could not tell the difference between the samples. Boar taint did not affect the sensory characteristics of pork from pigs reared outdoors. Even though there was a statistical difference in the texture liking of the samples from different sexes, the difference was not observed when the range of the evaluation scale was reduced. However, BB and females received higher scores for purchase intent than HB and males, respectively (P < 0.05).

Polymorphisms in the SOX9 region and testicular disorder of sex development (38,XX; SRY-negative) in pigs

Testicular XX disorder of sex development (XX DSD, SRY-negative), causing sterility, is quite frequently diagnosed in pig populations, however, its molecular background is still unknown. This disorder may affect carcass quality (boar taint) due to the presence of testicular tissue in animals with ambiguous female external genitalia. A chromosome fragment encompassing the SOX9 gene was previously considered as a candidate region in functional and association studies. We analyzed distribution of polymorphic variants in 5’UTR and in 3’-flanking regions of the SOX9 gene in a cohort of 12 XX DSD pigs and a panel of 116 normal females. Altogether, 8 previously known polymorphic sites were analyzed and no significant association under Bonferroni correction (P>0.0063) between DSD phenotype and identified SNPs was found. The region harboring the SOX9 gene was also searched for the presence of copy number variation (CNV) by fluorescence in situ hybridization technique (FISH), using a set of 7 BAC probes. A potential CNV region, manifested by size variation (large and small) of fluorescence signals, produced by a single BAC probe hybridizing downstream (approx. 500kb) of the SOX9 gene, was observed in 4 DSD cases. We conclude, that a new CNV polymorphism in the region harboring SOX9 gene can be considered as a promising marker for the DSD phenotype.

Chicory fructans in pig diet reduce skatole in back fat of entire male pigs

Androstenone, skatole and indole are main compounds responsible for boar taint, an off-odour in meat of some entire male pigs. Several feed ingredients derived from chicory have been reported to reduce fat skatole levels, while results for indole are more contradictory. The skatole-reducing effect is probably based on the prebiotic effects described for fructan compounds. Inulin and oligofructose have a high and low degree of polymerization, respectively. The fermentation rate decreases with an increasing degree of polymerization, which may result in differing effects of the compounds on skatole and/or indole levels. In this study we evaluated the effect of the inclusion of 5% inulin or 5% oligofructose during the last 3weeks before slaughter on carcass quality, concentration of skatole and indole in back fat as well as on the olfactory evaluation of boar taint in fat. Carcass weight did not differ between treatment groups but lean meat percentage increased when feeding oligofructose (P=0.019) compared to the control group, which is relevant for further research. Inclusion of 5% inulin or 5% oligofructose in the finisher diet of entire male pigs significantly reduced the back fat skatole concentration, without influence on indole. Olfactory score for boar taint tended to decrease when oligofructose was added to the diet.

Effects of immunocastration on growth performance, body composition, meat quality, and boar taint

The study objective was to evaluate the effect of immunocastration in the period between the first and second vaccinations and subsequently between the second vaccination and slaughter on growth performance, carcass composition, meat quality, and boar taint, and compare results in immunocastrated males (IC), uncastrated boars (UCM), surgically castrated barrows (CM), and gilts (FE). The study included 70 pigs of the Duroc × (Large White × Landrace) crossbreed. Upon the overall assessment of the selected fattening indicators (average daily gain, feed intake), significant differences between CM and the other groups were demonstrated. Meanwhile, no significant differences were found between the IC, UCM, and FE groups. In this test, immunocastrates showed no negative effect from the second vaccination in relation to those carcass value indicators evaluated in comparison with UCM and FE. CM showed adversely lower carcass value parameters compared the other groups. No significant differences in pH, meat colour, drip loss, shear force, and intramuscular fat were found. The values of these indicators obtained for IC converged with those measured in UCM and FE. It was demonstrated that immunocastration prevented the occurrence of undesired boar taint. Androstenone decreased by 77% and skatole by 71% in IC as compared to UCM.

Sensory evaluation of boar meat products by trained experts

Rearing entire male pigs, one of the alternatives for surgical castration, entails the possible occurrence of boar taint. This study aimed at the investigation of the acceptability of meat from entire male pigs in 8 different meat products (cutlets, bacon, blade loin, tenderloin, dry fermented sausage, cooked ham, dry-cured ham and minced meat) by trained assessors. Generally, the sensory evaluation of meat samples was affected the most in the androstenone (AEON) group, indicating that AEON is the most offensive boar taint compound for sensitive assessors. Differences between the meat products showed the highest potential for processing tainted meat in cold meat products, which was most likely due to the serving temperature on the one hand and production-related influences on the other. However, more insights regarding reducing and masking effects of production-related factors on boar taint are necessary.

Association analysis of SNPs in the porcine CYP2E1 gene with skatole, indole, and androstenone levels in backfat of a crossbred pig population

The occurrence of boar taint in meat from uncastrated males may significantly affect the economics of pork production. The aim of this study was to analyse associations of four single nucleotide polymorphisms (SNPs) in the porcine CYP2E1 gene with skatole, indole, and androstenone levels in the Czech Large White–Czech Landrace commercial crossbreds. The SNPs were: g.2412C>T, c.1422C>T, c.1423G>A and c.*14G>T. Skatole, indole and androstenone levels were estimated by HPLC, and genotypes at the SNPs were determined by PCR–RFLP. SNPs c.1423G>A and c.*14G>T were in complete linkage disequilibrium. In boars, all SNPs were associated with the indole levels (P<0.05; P<0.01). There also were differences in the skatole levels in different genotypes, but these were not significant. No associations with androstenone levels were found. The associations of the SNPs with indole compounds should be studied in other commercial populations of boars to verify the favourable alleles and genotypes, with the prospect for their application in marker-assisted selection.

Sensory evaluation of boar-taint-containing minced meat, dry-cured ham and dry fermented sausage by a trained expert panel and consumers

One of the main issues related to entire male pigs is the occurrence of boar taint, an off-odour, which compromises meat consumability. In this study, odour thresholds (indole: 24–65µgkg−1, skatole: 44–89µgkg−1, androstenone: 121–342µgkg−1) for the boar taint compounds were estimated in minced meat, dry fermented sausage and dry-cured ham. Afterwards, sensory evaluation of these products containing 10% tainted meat (minced meat and dry fermented sausage) or moderate boar taint compound levels (dry-cured ham) occurred. The beneficial effect of diluting tainted meat was demonstrated, as no significant difference in consumability was observed between gilts and 10% tainted meat by experts as well as consumers. Also dry-curing proved a promising technique for masking boar taint and preventing consumer dissatisfaction. The obtained results demonstrate the applicability of the estimated thresholds in meat as a tool for identifying masking and reducing strategies on the perception of boar taint.