Genomic Prediction and Genome-Wide Association Study for Boar Taint Compounds

With a perspective future ban on surgical castration in Europe, selecting pigs with reduced ability to accumulate boar taint (BT) compounds (androstenone, indole, skatole) in their tissues seems a promising strategy. BT compound concentrations were quantified in the adipose tissue of 1075 boars genotyped at 29,844 SNPs. Traditional and SNP-based breeding values were estimated using pedigree-based BLUP (PBLUP) and genomic BLUP (GBLUP), respectively. Heritabilities for BT compounds were moderate (0.30-0.52). The accuracies of GBLUP and PBLUP were significantly different for androstenone (0.58 and 0.36, respectively), but comparable for indole and skatole (~0.43 and ~0.47, respectively). Several SNP windows, each explaining a small percentage of the variance of BT compound concentrations, were identified in a genome-wide association study (GWAS). A total of 18 candidate genes previously associated with BT (MX1), reproduction traits (TCF21, NME5, PTGFR, KCNQ1, UMODL1), and fat metabolism (CTSD, SYT8, TNNI2, CD81, EGR1, GIPC2, MIGA1, NEGR1, CCSER1, MTMR2, LPL, ERFE) were identified in the post-GWAS analysis. The large number of genes related to fat metabolism might be explained by the relationship between sexual steroid levels and fat deposition and be partially ascribed to the pig line investigated, which is selected for ham quality and not for lean growth.

Genetic Correlations between Boar Taint Compound Concentrations in Fat of Purebred Boars and Production and Ham Quality Traits in Crossbred Heavy Pigs

Selecting pigs with reduced ability to accumulate boar taint (BT) compounds in their tissues is an alternative to male surgical castration. As the majority of slaughter pigs are crossbred, before selecting against BT in purebreds, it is essential to consider possible impacts on commercial traits in crossbreds. This study estimated the genetic correlations between BT compound levels measured in 1115 purebred pigs and carcass and ham quality traits collected in 26,577 crossbred Italian heavy pigs. Genetic correlations were estimated in bivariate Bayesian analyses including one BT trait and one production or ham quality trait at a time. Heritability of androstenone, skatole, and indole was 0.41, 0.49, and 0.37, respectively. A moderate negative correlation between skatole and carcass yield (-0.40), and between all BT compounds and backfat (from -0.26 to -0.55) was observed. Conversely, positive correlations (from 0.11 to 0.54) were found between skatole and ham fat thickness traits. Correlations between BT compounds and iodine number ranged from -0.07 (for androstenone) to -0.64 (for skatole), whereas those with PUFA ranged from -0.13 (for indole) to -0.33 (for skatole). Hence, reducing BT could decrease ham fat thickness and increase unsaturated fatty acids, with potential negative impacts on product quality.

Outdoor Finishing of Intact Male Portuguese Alentejano Pigs on a Sustainable High-Fiber Diet: Impacts on Blood, Growth, Carcass, Meat Quality and Boar Taint Compounds

This trial evaluated the effect of sex on the blood, growth, carcass, meat quality, and boar taint compounds in male Alentejano (AL) pigs (n = 30). From ~40 to 130 kg LW, castrated (C) and intact pigs (I and IExp groups) were fed commercial diets ad libitum. Between ~130 and 160 kg (slaughter), C and I pigs continued on commercial diets, while IExp were fed an experimental diet containing locally produced pulses and by-products aimed at reducing boar taint. At ~160 kg, blood urea levels were higher in IExp than C pigs, triacylglycerols were lower in both intact groups, and cortisol was lower in IExp. IExp pigs exhibited faster growth, improved feed conversion ratio, carcass higher commercial yield and leaner meat than C pigs. The loin intramuscular fat in intact pigs was lower, less saturated and more polyunsaturated, while total collagen was higher. Fat androstenone content was higher in intact pigs and skatole content was similar across treatments, although they were below threshold values for consumer detection. Finally, although boar taint compounds were low in intact AL pigs raised outdoors, adding pulses and by-products to the experimental diet did not result in a reduction in fat skatole content compared to pigs fed the commercial diet.

The Uptake and Deconjugation of Androstenone Sulfate in the Adipose Tissue of the Boar

Boars express high testicular levels of sulfotransferase enzymes, and consequently, the boar taint causing compound androstenone predominantly circulates as a steroid sulfate. Androstenone sulfate is suspected to function as a steroid reservoir that can be deconjugated to provide a source of free androstenone for accumulation. Therefore, the purpose of this study was to characterize the uptake and deconjugation of androstenone sulfate in the adipose tissue of the boar. Real-time PCR was used to quantify the expression of steroid sulfatase (STS) and several organic anion transporting polypeptides (OATPs) in the adipose tissue. Additionally, [³H]-androstenone sulfate was incubated with adipocytes or supernatant from homogenized fat to assess steroid uptake and conversion, respectively. A positive correlation existed between OATP-B expression and androstenone sulfate uptake (r = 0.86, p = 0.03), as well as between STS expression and androstenone sulfate conversion (r = 0.76, p < 0.001). Moreover, fat androstenone concentrations were positively correlated (r = 0.85, p < 0.001) with androstenone sulfate conversion and tended to increase with STS expression in early maturing boars. This suggests that androstenone sulfate uptake and deconjugation are mediated by OATP-B and STS, respectively, which may influence the development of boar taint in early maturing animals.

Antimelanoma activities of chimeric thiazole-androstenone derivatives

The discovery of chimeric anti-melanoma agents is reported. These molecules are potent growth suppressors of melanoma cells in vitro with growth inhibition of 50% (GI₅₀) values as low as 1.32 µM. Compounds were more toxic to melanoma cells in vitro than commonly used anti-melanoma agent dacarbazine as measured by TUNEL assay. They induced both caspase-independent apoptosis evident by colocalization of TUNEL with endonuclease G (EndoG) and caspase-mediated apoptosis measured by colocalization of TUNEL with caspase-activated DNase (CAD). In addition, compounds 3 and 5 strongly induced oxidative injury to melanoma cells as measured by TUNEL colocalization with heme oxygenase-1 (HO1). Dacarbazine induced only caspase-independent apoptosis, which may explain why it is less cytotoxic to melanoma cells than compounds 3, 4 and 5.

The Effects of Androstenone on the Plasma Serotonin, β-Endorphin, and Cortisol Concentrations in Thoroughbred Horses

Simple Summary

The development of horse managing tools is needed to prevent accidents and to improve welfare for domestic horses because the safety hazards for people who are exposed to horses are well documented. Androstenone, a pheromone secreted from boars, changes the behavior of dogs to become less excited. In horses, a previous study showed that a specific receptor for androstenone was expressed in the vomeronasal organ and nasal cavity. Horses treated with androstenone also showed more compliant behaviors. Thus, this study was conducted to investigate the mechanism of androstenone for changing horse behaviors. The change in the plasma concentrations of serotonin, β-endorphin, and cortisol in response to the treatment of androstenone was evaluated using an immunoassay. The results of this study demonstrated that androstenone may control the neuroendocrine system of horses, resulting in behavioral changes. This is the first work that studies the mechanism of pheromone treatment in horses and can be applied for further study about the effect of pheromone therapy on horses.

Abstract

Androstenone influences the changing behaviors of animals. Previous studies discovered that an androstenone receptor was expressed in horses and treatment with androstenone induced horses to be more compliant. As changes in the level of neuroendocrine factors result in animal behavioral changes, the objective of the study was to monitor the changes in the concentrations of 5-HT, β-endorphin, and cortisol in response to androstenone. Eight thoroughbred horses (five mares and three geldings) were treated with androstenone diluted in jojoba oil (10 µg/mL) and only oil for a control cross-overly. A handler applied the treatments to the horses′ nostril and rubbed for 5 s. Blood samples were collected before, 15, 30, and 60 min after each treatment. The concentrations of each neurotransmitter were analyzed by enzyme-linked immunosorbent assay. The concentrations of each neurotransmitter after the treatment were compared to its baseline concentration. The concentration of 5-HT of the androstenone-treated horses remained consistent throughout the experiment, while the concentration of the control group significantly decreased over time. The plasma concentration of β-endorphin in the androstenone-treated group also remained constant, whereas the concentration increased in the control group. Cortisol levels did not change in either the treated or untreated groups. An androstenone treatment triggers changes in the secretion of 5-HT and β-endorphin in horses.

The Binding of Free and Sulfated Androstenone in the Plasma of the Boar

Simple Summary

Boar taint is characterized by an off-odor or off-flavor in heated pork products that is caused by the accumulation of androstenone in the fat. We have previously demonstrated that androstenone is transported to the fat bound by the plasma protein albumin; however, it is unclear if androstenone sulfate, which is more abundant in the circulation, is transported in the same manner and if the transport of androstenone in the plasma influences the degree of accumulation in the fat. In this article, we determined that androstenone sulfate bound minimally in the plasma of the boar and suggested that this may leave it readily available to enter peripheral tissues, such as the fat where it may enzymatically return free androstenone. Additionally, we demonstrated that the binding of androstenone in the plasma varies significantly between boars with high and low concentrations of androstenone in the fat. This suggests that the binding of androstenone to albumin in the plasma affects the transport and distribution of androstenone within the boar.

Abstract

Androstenone circulates in the plasma bound to albumin before accumulating in the fat, resulting in the development of boar taint. Androstenone sulfate is more abundant in the circulation than free androstenone; however, it is unclear how androstenone sulfate is transported in the plasma and if steroid transport affects the development of boar taint. Therefore, the purpose of this study was to characterize the binding of androstenone sulfate in boar plasma and determine if variability in steroid binding affects the accumulation of androstenone in the fat. [³H]-androstenone sulfate was incubated with plasma and the steroid binding was quantified using gel filtration chromatography. Inter-animal variability was assessed by quantifying androstenone binding specificity in plasma obtained from boars that had high or low fat androstenone concentrations at slaughter. Androstenone sulfate bound minimally in the plasma and to isolated albumin, which suggests that it is transported primarily in solution. The specific binding of androstenone quantified in plasma and isolated albumin from low fat androstenone animals was significantly higher (p = 0.01) than in high fat androstenone boars. These results indicate that the binding of androstenone to albumin varies amongst individual animals and affects the transport of androstenone in the plasma and accumulation in the fat of the boar.

Correlation Networks Provide New Insights into the Architecture of Testicular Steroid Pathways in Pigs

Steroid metabolism is a fundamental process in the porcine testis to provide testosterone but also estrogens and androstenone, which are essential for the physiology of the boar. This study concerns boars at an early stage of puberty. Using a RT-qPCR approach, we showed that the transcriptional activities of several genes providing key enzymes involved in this metabolism (such as CYP11A1) are correlated. Surprisingly, HSD17B3, a key gene for testosterone production, was absent from this group. An additional weighted gene co-expression network analysis was performed on two large sets of mRNA-seq to identify co-expression modules. Of these modules, two containing either CYP11A1 or HSD17B3 were further analyzed. This comprehensive correlation meta-analysis identified a group of 85 genes with CYP11A1 as hub gene, but did not allow the characterization of a robust correlation network around HSD17B3. As the CYP11A1-group includes most of the genes involved in steroid synthesis pathways (including LHCGR encoding for the LH receptor), it may control the synthesis of most of the testicular steroids. The independent expression of HSD17B3 probably allows part of the production of testosterone to escape this control. This CYP11A1-group contained also INSL3 and AGT genes encoding a peptide hormone and an angiotensin peptide precursor, respectively.

Endocrine Fertility Parameters-Genomic Background and their Genetic Relationship to Boar Taint in German Landrace and Large White

The surgical castration of young male piglets without anesthesia is no longer allowed in Germany from 2021. One alternative is breeding against boar taint, but shared synthesis pathways of androstenone (AND) and several endocrine fertility parameters (EFP) indicate a risk of decreasing fertility. The objective of this study was to investigate the genetic background between AND, skatole (SKA), and six EFP in purebred Landrace (LR) and Large White (LW) populations. The animals were clustered according to their genetic relatedness because of their different origins. Estimated heritabilities (h²) of AND and SKA ranged between 0.52 and 0.34 in LR and LW. For EFP, h² differed between the breeds except for follicle-stimulating hormone (FSH) (h²: 0.28-0.37). Both of the breeds showed unfavorable relationships between AND and testosterone, 17-β estradiol, and FSH. The genetic relationships (r_g) between SKA and EFP differed between the breeds. A genome-wide association analysis revealed 48 significant associations and confirmed a region for SKA on S us S crofa chromosome (SSC) 14. For EFP, the results differed between the clusters. In conclusion, r_g partly confirmed physiologically expected antagonisms between AND and EFP. Particular attention should be spent on fertility traits that are based on EFP when breeding against boar taint to balance the genetic progress in both of the trait complexes.

Influence of Immunocastration on Slaughter Traits and Boar Taint Compounds in Pigs Originating from Three Different Terminal Sire Lines

Simple Summary

Due to the negative public opinion and welfare issues related to surgical castration, gradual introduction of alternatives like entire males and immunocastrates is taking place. Despite several economical and welfare advantages that the alternatives offer, numerous issues (i.e., boar taint, meat quality alterations), as well as their interactions with rearing and breeding (genetic) factors remain unanswered. Therefore, the focus of this study was to investigate the possibility of using different commercial sire lines in three male sex categories (entire males, immunocastrates, surgical castrates) and to compare their carcass traits, meat quality and boar taint compounds. A significant effect of terminal sire line and/or male category together with their interaction was observed for most of the investigated carcass and meat quality traits. The observed interaction should be taken into consideration when deciding on the production of a specific male category.

Abstract

The aim of the research was to investigate the influence of terminal sire line (TSL) and male category (MC) on carcass and meat quality of commercial fatteners. The study was performed on 180 pigs originating from three terminal sire lines: A (Pietrain × Large White), B (pure Pietrain), and C (Pietrain × Duroc × Large White), being assigned to three groups according to MC: immunocastrates (IC, n = 60), surgical castrates (SC, n = 60) and entire males (EM, n = 60). TSL affected most of the carcass and meat quality traits, together with the androstenone concentration. At the same time, MC had a significant effect on fat thickness, ham circumference, drip loss, cooking loss and androstenone and skatole concentrations. A significant interaction effect was observed for carcass length and ham circumference, as well as for most of the measured meat quality traits (except cooking loss, CIE L*, CIE b*, and Warner Bratzler Shear Force (WBSF)). Among the three investigated sire lines, immunocastration was shown to be most beneficial for fatteners sired by the TSL C. However, if deciding to raise EM, fatteners from the TSL B are recommended in terms of carcass and meat quality, although strategies for avoiding boar taint in their carcasses must be taken into consideration.

Applying an association weight matrix in weighted genomic prediction of boar taint compounds

Biological information regarding markers and gene association may be used to attribute different weights for single nucleotide polymorphism (SNP) in genome-wide selection. Therefore, we aimed to evaluate the predictive ability and the bias of genomic prediction using models that allow SNP weighting in the genomic relationship matrix (G) building, with and without incorporating biological information to obtain the weights. Firstly, we performed a genome-wide association studies (GWAS) in data set containing single- (SL) or a multi-line (ML) pig population for androstenone, skatole and indole levels. Secondly, 1%, 2%, 5%, 10%, 30% and 50% of the markers explaining the highest proportions of the genetic variance for each trait were selected to build gene networks through the association weight matrix (AWM) approach. The number of edges in the network was computed and used to derive weights for G (AWM-WssGBLUP). The single-step GBLUP (ssGBLUP) and weighted ssGBLUP (WssGBLUP) were used as standard scenarios. All scenarios presented predictive abilities different from zero; however, the great overlap in their confidences interval suggests no differences among scenarios. Most of scenarios of based on AWM provide overestimations for skatole in both SL and ML populations. On the other hand, the skatole and indole prediction were no biased in the ssGBLUP (S1) in both SL and ML populations. Most of scenarios based on AWM provide no biased predictions for indole in both SL and ML populations. In summary, using biological information through AWM matrix and gene networks to derive weights for genomic prediction resulted in no increase in predictive ability for boar taint compounds. In addition, this approach increased the number of analyses steps. Thus, we can conclude that ssGBLUP is most appropriate for the analysis of boar taint compounds in comparison with the weighted strategies used in the present work.

Combined Effect of Dietary Protein, Ractopamine, and Immunocastration on Boar Taint Compounds, and Using Testicle Parameters as an Indicator of Success

This study investigates the combined effect of immunocastration, dietary protein level (low, medium or high) and ractopamine hydrochloride supplementation (0 or 10 mg/kg) on the adipose concentrations of androstenone, skatole and indole in pigs, and explores whether body mass, carcass fatness or testicular parameters may be indicators of boar taint in these carcasses. Immunocastration was successful in decreasing testicle functioning, and adipose androstenone and skatole concentrations, in all individuals. Immunocastration decreased testicle weight and length, seminiferous tubule circumference and epithelium thickness. Testicle tissue from immunocastrates was also paler, and less red in color, in comparison to non-castrated controls. Dietary protein level and ractopamine hydrochloride supplementation had no influence on the adipose concentration of androstenone, skatole and indole. Testicle size and color were moderate to strong indicators of androstenone and skatole concentrations in the carcasses, and thus vaccination success. Immunocastration together with the adjustment of dietary protein and ractopamine hydrochloride supplementation, is successful in preventing boar taint while maintaining growth performance.

Developing and Understanding Olfactory Evaluation of Boar Taint

Simple Summary

Boar taint is an unpleasant smell and taste of fat of uncastrated male pigs. Growing welfare concerns are pushing towards a ban on the common practice of castrating male piglets as a means to prevent boar taint. This pushes the pork industry to apply alternative strategies to prevent the consumption of tainted of meat. Detecting boar taint is an important aspect of solving this problem, both as a control strategy in slaughterhouses and in boar taint research. This study provides a training protocol and scoring method as well as recommendations for evaluating boar taint.

Abstract

Trained expert panels are used routinely in boar taint research, with varying protocols for training of panelists and scoring methods. We describe a standardized process for training and scoring, to contribute to standardize the olfactory detection of boar taint. Three experiments are described in which we (1) evaluate the importance of training and the effect of the previous sample, (2) determine detection thresholds on strips and in fat for our panel, and (3) test priming panelists before boar taint evaluation. For the final evaluation of boar taint, we propose a consistent three-person evaluation scoring on a 0–4 scale using a final mean score of 0.5 as the cut-off for boar taint. This gave an optimal sensitivity of 0.81 and a specificity of 0.56 compared to chemical cut-offs. Even limited training proved useful, but priming assessors with strips did not improve the evaluation of fat samples. Detection thresholds were higher in fat compared to strips, except for indole. We recommend panelists to always smell a non-tainted control sample after a tainted one as a ‘reset’ mechanism, before continuing. For longitudinal studies, we additionally advise to set up an expert panel with a fixed number of assessors performing each evaluation in duplicate.

Pork Production with Entire Males: Directions for Control of Boar Taint

Simple Summary

Castration of male piglets has traditionally been carried out to control boar taint, but animal welfare concerns about surgical castration has brought this practice under scrutiny. In addition, castration decreases growth performance and increases the environmental impact of pork production, so alternatives to castration are needed to control boar taint. In this review, we summarize the current knowledge on boar taint metabolism and outline some key areas that require further study. We also describe some opportunities for controlling the boar taint problem and propose that by defining the differences in metabolic processes and the genetic variations that can lead to boar taint in individual pigs, we can design effective custom solutions for boar taint.

Abstract

Boar taint is caused by the accumulation of androstenone and skatole and other indoles in the fat; this is regulated by the balance between synthesis and degradation of these compounds and can be affected by a number of factors, including environment and management practices, sexual maturity, nutrition, and genetics. Boar taint can be controlled by immunocastration, but this practice has not been accepted in some countries. Genetics offers a long-term solution to the boar taint problem via selective breeding or genome editing. A number of short-term strategies to control boar taint have been proposed, but these can have inconsistent effects and there is too much variability between breeds and individuals to implement a blanket solution for boar taint. Therefore, we propose a precision livestock management approach to developing solutions for controlling taint. This involves determining the differences in metabolic processes and the genetic variations that cause boar taint in specific groups of pigs and using this information to design custom treatments based on the cause of boar taint. Genetic, proteomic or metabolomic profiling can then be used to identify and implement effective solutions for boar taint for specific populations of animals.

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

Simple Summary

Surgical 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.

Abstract

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.

Genetic determinism of boar taint and relationship with growth traits, meat quality and lesions

Breeding entire males is an alternative to surgical castration to improve their welfare. However, entire males may have a major quality defect called boar taint. Boar taint is partly due to the presence of androstenone in fat. In this study, we estimated the genetic parameters between androstenone and production traits to evaluate the consequences of selection against boar taint for traits of interest. We focused on growth traits, meat quality, lesions, hormone levels and computerised tomography measurements in purebred Piétrain (P) or Piétrain cross Large White (X) entire males. The number of measured animals varied from 670 P and 734 X for hormones concentrations to 553 P and 645 X for computerised tomography measurements. Skin lesions were measured on live pigs shortly after mixing, at the end of the fattening period, and on carcasses. Heritabilities of traits measured by tomography ranged from low to high: femur density (P: 0.34, X: 0.69), loin eye area (P: 0.53, X: 0.88) and loin eye density (P: 0.12, X: 0.18). The mean number of lesions at each stage was lower in purebred pigs than in crossbreds (entering the fattening stage 4.01 in P and 4.68 in X; before slaughter 3.72 in P and 4.22 in X; on carcass 4.50 in P and 4.96 in X). We also observed a decrease in the average number of lesions between the two stages in live pigs. We found high genetic correlations between stages in purebred pigs (0.74 to 0.76) but low correlations (−0.30 to 0.29) in crossbred pigs. Selection aiming to decrease fat androstenone is feasible (h² = 0.57 in P and h² = 0.71 in X). It would have overall positive effects on meat production and quality traits. Selection aiming to reduce plasma oestradiol would strongly reduce the level of fat androstenone (rg = 0.89 in P and rg = 0.84 in X). Selection against oestradiol is easier and less invasive since it would only require a blood sample rather than a fat biopsy in live animals.

Characterization of eQTLs associated with androstenone by RNA sequencing in porcine testis

Characterization of genetic variants affecting genome-wide gene expression levels (expression quantitative trait loci or eQTLs) in pig testes may improve our understanding of genetic architecture of boar taint (an animal welfare trait) and helps in genome-assisted or genomic selection programs. The aims of this study were to identify eQTLs associated with androstenone, to find candidate eQTLs for low androstenone, and to validate the top eQTL by reverse transcriptase quantitative PCR (RT-qPCR). Gene expression profiles were obtained by RNA sequencing in testis from Danish cross-bred pigs and genotype data by 80K single nucleotide polymorphism panel. A total of 262 eQTLs [false discovery rate (FDR) < 0.05] were identified by using two software packages: Matrix eQTL and Krux eQTL. Of these, 149 cis-acting eQTLs were significantly associated with androstenone concentrations and gene expression (FDR < 0.05). The eQTLs were associated with several genes of boar taint relevance including CYP1A2, CYB5D1, and SPHK2. One eQTL gene, AMPH, was differentially expressed (FDR < 0.05) and affected by chicory. Five candidate eQTLs associated with low androstenone concentrations were discovered, including the top eQTL associated with CYP1A2. RT-qPCR confirmed target gene expression to be significantly (P < 0.05) different based on eQTL genotypes. Furthermore, eQTLs were enriched as QTLs for 15 boar taint related traits from the PigQTLdb. This is the first study to report eQTLs in testes of commercial crossbred pigs used in pork production and to reveal genetic architecture of boar taint. Potential applications include development of a DNA test and in advanced genomic selection models for boar taint.

Reduction of androstenone perception in pan-fried boar meat by different masking strategies

BACKGROUND

Consumers highly sensitive to androstenone María (AND) will probably reject meat from entire male pigs, which tends to have high levels of this hormone. To avoid this, the effect of different masking strategies (sprinkling with mixed spices or fennel, marinating and breading with garlic-parsley or curry) on the sensory parameters of pork loin chops obtained from entire animals with high levels of AND (1.0-2.9 mg kg^-1 AND in fat) and castrated animals (<0.4 mg kg^-1 AND in fat), both with low levels of skatole (<0.1 mg kg^-1 skatole in fat) was investigated.

RESULTS

The garlic-parsley breadcrumbs led to the highest reduction in the perception of AND compared with the other masking strategies used, and preserved the juiciness of the product. There was a negative correlation between AND and fat content.

CONCLUSION

AND odor and flavor can be reduced in meat from entire male pigs by using suitable strategies, the best strategy being the garlic-parsley breadcrumbs. © 2017 Society of Chemical Industry.

Association of Cytokine Production with Hormone Level and Sensory Responses during the Formation of Psychoactive Drug Addiction in Men

We performed immunophysiological examination of 144 men aged 17-25 years, patients with psychoactive substance dependence, episodic psychoactive drug users, and conditionally healthy individuals. Associations of proinflammatory cytokine production with age, sex, hormone levels, and olfactory and nociceptive indices were revealed in cases of psychoactive drug use and formation of addiction. Predictive models based on the use of androstenone aversion, pressure algometry testing, and immunological parameters were proposed.

Efficiency of genomic prediction for boar taint reduction in Danish Landrace pigs

Genetic selection against boar taint, which is caused by high skatole and androstenone concentrations in fat, is a more acceptable alternative than is the current practice of castration. Genomic predictors offer an opportunity to overcome the limitations of such selection caused by the phenotype being expressed only in males at slaughter, and this study evaluated different approaches to obtain such predictors. Samples from 1000 pigs were included in a design which was dominated by 421 sib pairs, each pair having one animal with high and one with low skatole concentration (≥0.3 μg/g). All samples were measured for both skatole and androstenone and genotyped using the Illumina SNP60 porcine BeadChip for 62 153 single nucleotide polymorphisms. The accuracy of predicting phenotypes was assessed by cross‐validation using six different genomic evaluation methods: genomic best linear unbiased prediction (GBLUP) and five Bayesian regression methods. In addition, this was compared to the accuracy of predictions using only QTL that showed genome‐wide significance. The range of accuracies obtained by different prediction methods was narrow for androstenone, between 0.29 (Bayes Lasso) and 0.31 (Bayes B), and wider for skatole, between 0.21 (GBLUP) and 0.26 (Bayes SSVS). Relative accuracies, corrected for h², were 0.54–0.56 and 0.75–0.94 for androstenone and skatole respectively. The whole‐genome evaluation methods gave greater accuracy than using only the QTL detected in the data. The results demonstrate that GBLUP for androstenone is the simplest genomic technology to implement and was also close to the most accurate method. More specialised models may be preferable for skatole.

Responsiveness of human neonates to the odor of 5α-androst-16-en-3-one: a behavioral paradox?

The odorous steroid 5α-androst-16-en-3-one (AND) occurs in numerous biological fluids in mammals, including man, where it is believed to play a chemocommunicative role. As AND was recently detected in milk and amniotic fluid, sensitivity and hedonic responses to this substance were assessed in human neonates. To this aim, respiration and facial expressions were recorded in 3-day-old newborns in response to aqueous solutions of AND, ranging from 500ng/mL to 0.5 fg/mL. Although analyses of respiratory rate did not lead to clear-cut results, the newborns changed their facial expressions at concentrations not detected by adults in a triangle test. Newborns displayed negative facial actions of longer duration to AND relative to an odorless control. Thus, AND may be considered to be offensive to newborns, which is a counterintuitive outcome as they are exposed to this compound in the womb (and it should therefore be familiar), in milk, and on the mother's skin surface (and it should therefore be conditioned as positive). Multiple reasons for this perceptual-behavioral paradox are discussed.

Suppression of boar taint in cryptorchid pigs using a vaccine against the gonadotropin-releasing hormone

Thirteen unilaterally cryptorchid Large White pigs, which had been immunized at 4 and 8 weeks of age and a third time at 64 ± 4 kg body weight against the gonadotropin releasing hormone with the vaccine Improvac®, were slaughtered at the age of 170 ± 9 days at a body weight of 102 ± 12 kg. Twelve pigs tested negative in the olfactory test of the salivary gland; their descended testicles were small and their fat androstenone concentration was low compared to normally developed boars of a previous experiment which had been vaccinated twice with Improvac® according the manufacturer's recommendation. One cryptorchid boar, which tested positive in the olfactory test and whose testicular weight and fat androstenone concentration corresponded to values of unvaccinated boars of the same age, obviously had not responded to the vaccination. It is an open question if the vaccination protocol for normal boars is sufficient to prevent boar taint in the majority of cryptorchid pigs, too.

Boar taint in entire male pigs: a genomewide association study for direct and indirect genetic effects on androstenone

Androstenone is one of the compounds causing boar taint of pork and is highly heritable (approximately 0.6). Recently, indirect genetic effects (IGE; also known as associative effects or social genetic effects) were found for androstenone, meaning that pen mates (boars) affect each other's androstenone level genetically. Similar to estimating variance components with a direct-indirect animal model, direct and indirect genetic SNP effects can be estimated for androstenone. This study aims to detect SNP with significant direct genetic effects and IGE on androstenone. The dataset consisted of 1,282 noncastrated boars (993 boars genotyped) from 184 groups of pen members. After quality control, 46,421 SNP were included in the analysis. One model for single-SNP regression was fitted, where both the direct SNP effect of the individual itself and the indirect SNP effects of its pen mates were included. None of the SNP (direct or indirect) were found genomewide significant. One QTL on SSC6 was chromosome-wide significant for the direct effect. A single SNP on SSC9 and 2 regions and a single SNP on SSC14 were found for the indirect effect. A backwards elimination method and haplotype analysis were used to quantify the variance explained by the SNP. The backwards elimination method identified 4 independent regions affecting androstenone. The QTL on SSC6 explained 2.1 and 2.6% of the phenotypic variance using the backwards elimination method or the haplotype analysis. The QTL on SSC14 explained 3.4 and 2.7% of the phenotypic variance using the backwards elimination method or the haplotype analysis. The single association on SSC9 explained 2.2% of the phenotypic variance. All significant QTL together explained 7 to 8% of phenotypic variance and 40 to 44% of the total genetic variance available for response to selection. Besides the newly discovered QTL and the confirmation of known QTL, this study also presents a methodology to model SNP for IGE.

A rapid radioimmunological evaluation of the androstenone content in boar fat

Fat from boars containing androstenone is absorbed to a piece of filter paper. The filter paper is then placed in a tube and a buffer containing antibodies against androstenone is added. Following incubation the filter paper is removed, and by measurement of the residual binding capacity for androstenone in the buffer a relative value for androstenone content in the fat is obtained.

The coefficient of correlation between the results obtained by this rapid method and the ordinary radioimmunoassay was −0.95.