Search

Boar taint is a quality defect in meat, related to accumulation of skatole and androstenone in male pigs. The levels of skatole and its main metabolites in plasma and urine samples were measured with a validated liquid chromatography-MS method and related to activity of hepatic cytochrome P450 (CYP450) in order to identify 'fast metabolizing' pigs. Urine (n=46), blood (n=12), liver (n=25) and adipose tissue (n=46) were sampled from a total of 46 entire male pigs. Skatole levels in fat were negatively correlated to CYP2E1 activity and positively to 3-hydroxy-3-methyloxindole (HMOI), indole-3-carboxylic acid (ICA) and 2-aminoacetophenone in urine. HMOI and ICA levels in urine were the best predictors of high skatole levels in fat. In summary, the present study provided further evidence for the key role of CYP2E1 in skatole metabolism and suggested that measurement of HMOI and/or ICA in urine might provide information about skatole levels in live pigs.

In today's production systems, pigs raised for slaughter are mixed many times, resulting in stress and fighting. The negative consequences of mixing are probably more severe with entire males than with castrates, as they fight more. In this project, we studied a system without castration where entire male pigs met unfamiliar pigs only once. Piglets from two litters were allowed to visit each other from circa 2 weeks of age through an opening between the farrowing pens. Entire males from these litters were kept in intact groups from weaning and onwards, and they were slaughtered pen-wise in intact groups. Control pigs were raised and weaned in their litters and mixed with unknown pigs when moved to the growing-finishing unit. They were slaughtered by split marketing based on individual weight. In total, 96 entire males from 24 litters were studied. Activity and social interactions of pigs were studied by direct observations on three observation occasions per pen for pigs kept in intact groups and four occasions for control pigs. All pigs were inspected for skin lesions during raising and at slaughter. Results showed that fewer pigs in intact groups were resting (17.1% v. 28.5%; P = 0.044) and they showed less aggressive behaviour (16.1 v. 27.7 number of interactions per hour; P = 0.001) than control pigs when moved to the growing-finishing unit. They also got fewer skin lesions compared with control pigs (15 v. 35; P < 0.001). Consequently, control pigs tended to grow slower during the 1st week after mixing; however, growth rate during the whole growing-finishing phase did not differ between treatments (P = 0.205). Control pigs directed more aggressive behaviour towards non-litter mates than towards litter mates during the whole growing-finishing phase, whereas pigs from the other treatment made no difference between litter mates and other familiar pigs. At 67 kg, there was more sexual behaviour (mounting) among control pigs (7.6 v. 3.4; P = 0.033), but after slaughter no differences were found in testis weight or boar taint compounds. At slaughter, more entire males that were slaughtered pen-wise and kept in intact groups were without skin lesions compared with the mixed control pigs (74% v. 13%; P < 0.001). This study shows that the welfare of entire male pigs can be improved by socialising piglets and by keeping them in intact groups during raising and at slaughter.

The aim of this study was to investigate the effect of giving a two-dose regimen of gonadotropin-releasing hormone vaccine, Improvac® (Pfizer Ltd), earlier than currently recommended, on performance and behaviour of growing/finishing pigs. Cross-bred male pigs (n = 192) were randomly allocated, within a litter, into four groups at birth: one group of pigs surgically castrated without anaesthesia before one week of age, a second group of early vaccinated pigs given Improvac at 10 and 14 weeks of age, a third group of standard vaccinated pigs given Improvac at 16 and 20 weeks of age, so that the second vaccination was given 4 to 6 weeks before slaughter as recommended by the manufacturer, and a fourth group of entire male pigs. The experiment started when the pigs were 12 weeks old and lasted until 25 weeks of age, when the pigs were slaughtered. The pigs were fed restrictedly. Daily weight gain and feed conversion during the entire raising period did not differ significantly between groups. Estimated lean meat content of early vaccinated and surgically castrated pigs was lower when compared with entire male pigs, whereas standard vaccinated pigs did not differ from entire males. Dressing percentage was higher in early vaccinated and surgically castrated pigs than in standard vaccinated and entire male pigs, partly because of lower size and weight of reproductive organs. For both groups of vaccinated pigs, both problematic and non-problematic behaviours decreased after their second injection, from the levels of entire males to those of surgically castrated pigs. After the second injection, pigs of both vaccination groups performed no mountings, in contrast with entire male pigs of the same age. Skin lesions at slaughter were fewer and less severe for vaccinated pigs compared with entire male pigs. No difference in income per carcass was observed for surgically castrated or vaccinated pigs. However, for entire male pigs the income was lower, as the payment system in Sweden also takes into consideration the additional cost for boar taint analyses and reduced payment for tainted carcasses. Under our experimental conditions, early vaccination with Improvac can be used as an alternative to the recommended schedule to minimise problematic behaviour with unaffected profitability.

The aim of this study was to investigate the effect of a vaccine against gonadotropin-releasing hormone (GnRH), Improvac(®) (Pfizer Ltd), administered at a pre- or early pubertal stage on boar taint, hormonal status and reproductive organs. Crossbred male pigs (Swedish Yorkshire dams×Swedish Landrace sires or Swedish Yorkshire sires, n=192) were at birth randomly allocated to four groups: one group of pigs surgically castrated without anaesthesia before age 1 week, a second group of early vaccinated pigs given Improvac at ages 10 and 14 weeks, a third group of standard vaccinated pigs given Improvac at ages 16 and 20 weeks, and a fourth group of entire male pigs. Following the second vaccine injection, antibody titres increased rapidly, accompanied by a rapid decrease in testosterone and a slower decrease of skatole in plasma to the same low levels as for surgically castrated pigs. At slaughter, the levels of androstenone and skatole in adipose tissue were low in surgically castrated and vaccinated pigs, whereas entire male pigs had elevated levels (p<0.001). Similarly, oestradiol was at low levels for surgically castrated and vaccinated pigs, whereas entire male pigs had elevated levels (p<0.001). IGF-1 was lowest for surgically castrated pigs and highest for entire male pigs, with vaccinated pigs at an intermediate level (p<0.001). At slaughter, reproductive organs were small in pigs vaccinated with Improvac, and smaller in pigs vaccinated early (p<0.001). Under our experimental conditions, early vaccination with Improvac can be used as an alternative to the recommended schedule with maintained control of boar taint and testicular secretory activity., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Postmortem changes in pork muscle protein phosphorylation in relation to the RN(-) genotype were investigated using one-dimensional gel electrophoresis and a phosphor specific staining. The phosphorylation levels of several protein bands were found to be affected by the RN(-) genotype and to change during postmortem development. Glycogen phosphorylase, phosphofructokinase, and pyruvate kinase were found in protein bands affected by the RN(-) genotype, and the phosphorylation profile indicates that part of the increased rate and extended pH decline of the RN(-) genotype could be a consequence of phosphorylation of these key enzymes during the postmortem metabolism. The results illustrate that the protein phosphorylation level of the muscle proteins could be interpreted as a global metabolic fingerprint containing information about the activity status of the enzymes in the postmortem metabolism.

Gonadotropin-releasing hormone (GnRH) vaccine (Improvac(®)) is effective at diminishing boar taint by interfering with testis function. Early pre-pubertal vaccination at 10 and 14 weeks-of-age could be desirable if sufficient and sustained effects could be achieved. Crossbred male pigs (n=24) were randomly assigned to three groups each with eight individuals: an unvaccinated control group, one group vaccinated with Improvac(®) early at ages 10 and 14 weeks, and a third group vaccinated with Improvac at the standard ages of 16 and 20 weeks. The average age at slaughter was 25 weeks. At slaughter, reductions in testes weight and bulbourethral gland length of vaccinated pigs compared with controls were observed (P<0.001), accompanied by lowered testosterone concentrations in peripheral blood (P<0.001). The diameter of tubuli seminiferi was affected; being 18% smaller in standard and 38% smaller in early vaccinated males, compared with controls (P<0.01). Leydig cells in vaccinated pigs became pycnotic, and their number decreased in early vaccinated pigs. Spermatogenesis was disrupted, evidenced by spermatocyte loss among standard vaccinated pigs to severe spermatogenic arrest among early vaccinated pigs. This histological picture was reflected in the absence of epididymal spermatozoa in 5 of 8 early vaccinated pigs and a dramatic reduction in the remaining 3 early vaccinated pigs. Among standard vaccinated pigs, 5% of the spermatozoa were morphologically normal (>70% in controls, P<0.01). Early vaccination caused a more severe disruption of testicular structure and function than standard vaccination, thus providing an alternative for immunocastration of male pigs., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The objective of this study was to determine the short and long term effects of a gonadotropin-releasing hormone (GnRH) vaccine (Improvac Pfizer Ltd.), on sexual maturity, development of the reproductive organs, and the morphology of caudal epididymal spermatozoa in non-castrated male pigs. The pigs were slaughtered 4, 16 or 22 weeks after the second Improvac vaccination. A total of 80 crossbred non-castrated male pigs were included in this study comprising two experiments, a short-effect (Experiment 1) and a long-effect (Experiment 2). The first experiment included 56 pigs, 24 of them were maintained as controls and 32 were vaccinated twice, and slaughtered 4 weeks after the second vaccination. The second experiment included 24 pigs, 12 controls and 12 vaccinated twice, and slaughtered either 16 weeks (n=6) or 22 weeks (n=6) after the second vaccination. None of the immunized pigs was sexually mature at slaughter, i.e. 4, 16 or 22 weeks after second vaccination. Corresponding results of the control pigs showed that 50% had reached sexual maturity at the age corresponding to 4 weeks after the second vaccination, and 100% at slaughter 16, respectively, 22 weeks after vaccination. At 4, 16 and 22 weeks after second vaccination both testes weight and bulbourethral length were significantly reduced (p<0.001). The percentages of proximal droplets and abnormal heads were significantly lower in the control pigs than in the immunized pigs at slaughter 4 weeks after vaccination, whereas distal droplets were higher. For the other morphological parameters no significant differences were seen, but all mean values except for acrosome defects were numerically lower in the control pigs compared with the immunized pigs. For pigs slaughtered 16 or 22 weeks after vaccination, the vaccination effect was significant for percentages of proximal droplets, distal droplets, acrosome defects, acrosome abnormality and abnormal heads (p=0.017-0.001). The immunization clearly disrupted the number and morphology of the interstitial Leydig cells, lasting throughout the study period (4-22 weeks after vaccination). Spermatogenesis was also clearly affected in the immunized pigs, to various degrees, from mild disruption (spermatocyte loss, decrease of the normal number of layers of germ cells) to severe loss of germ cells including tubuli with Sertoli cells-only (complete disappearance of germ cells), also covering the entire study period. The results indicated that the effect of immunization persisted for at least 22 weeks after the second vaccination.

The objective of this study was to evaluate the long-term effect of a gonadotropin-releasing hormone (GnRH) vaccine, Improvac (Pfizer Ltd.), on the levels of GnRH antibodies, testosterone, estrone sulphate (E1S) and androstenone, as well as skatole and indole in male pigs. Additionally, the long-term effect of immunocastration on social and sexual behaviour was studied. Male pigs were assigned to two treatment groups: a treatment group given two doses of Improvac (n=12) and a control group of entire male pigs (n=12). The pigs were kept either 16 or 22 weeks after vaccination. Blood samples were collected five or six times; prior to both first and second vaccination, then three or four times during the 16 or 22 week period after second vaccination. Immunocastration significantly reduced levels of testosterone and E1S in plasma, and levels of androstenone in fat (P<0.001 for all). Skatole and indole levels in plasma and fat were also lower in immunocastrated pigs than in entire male pigs. These effects lasted up to 22 weeks after the second vaccination. Testis weight and bulbourethral gland length were lower in immunocastrated pigs at slaughter and these pigs showed less social, manipulating and aggressive behaviour than entire male pigs. The immunocastrated pigs remained sexually inactive throughout the study. Our study represents a further step in the evaluation of the effectiveness of Improvac as an alternative to surgical castration of entire male pigs. It shows that Improvac may have an extended effect compared with that currently implied by the directions for use.

The objective of this study, comprising two trials, was to evaluate the effect of a gonadotropin-releasing hormone (GnRH [corrected] vaccine Improvac; Pfizer Ltd) in a sample of the Swedish pig population. The pigs (n = 120) were assigned to three groups: control (entire male pigs), surgical castration and immunization against GnRH. Surgically castrated pigs did not express detectable levels of either testosterone or estrone sulphate (E1S) in plasma, or androstenone in fat and had lower skatole and indole levels in fat than entire male pigs. Immunization significantly reduced testes weight and bulbourethral gland length, plasma levels of the testicular hormones testosterone and E1S, and fat levels of androstenone, skatole and indole. Skatole levels in plasma were significantly lower than in entire male pigs in the second trial, but not in the first due to overall low skatole levels. All immunized pigs and surgically castrated pigs expressed skatole concentrations in fat below the level of 0.2 microg/g, above which meat is regarded as tainted. In contrast, eight entire male pigs exceeded this level. Indole levels in plasma from immunized pigs were lower than those from entire male pigs. Surgical castration caused lower daily weight gain in the suckling period compared with piglets raised intact, whereas in the post-weaning period no difference was observed. Immunization resulted in higher feed intake and daily weight gain after the second injection. The estimated lean meat content was improved in comparison with the castrated pigs, but was lower than for entire male pigs. Dressing percentage was lower in immunized pigs than in surgically castrated and entire male pigs. The frequency of skin damage did not differ between immunized and entire male pigs or between immunized and surgically castrated pigs.

Androstenone is one of the main compounds responsible for boar taint, and 3beta-hydroxysteroid dehydrogenase (3betaHSD) might be involved in its metabolism. In this study, the gene expression of 3betaHSD and 17beta-hydroxysteroid dehydrogenase (17betaHSD) were determined by real-time PCR analysis and related to the concentrations of androstenone, testosterone, and estrone sulphate (E1S). The experiments were performed on gonadally intact male pigs classified based on high or low fat androstenone concentrations, as predetermined by HPLC, as well as on immunocastrated and surgically castrated male pigs. The male pigs with high androstenone concentrations in fat had low 3betaHSD gene expression in liver and testis. Moreover, the 17betaHSD gene expression in liver, but not in testis, varied negatively with fat androstenone concentrations. Immunocastrated and surgically castrated male pigs had nondetectable concentrations of fat androstenone and plasma testosterone and E1S, and the castration procedure induced a significant increase of 3betaHSD and 17betaHSD gene expression. The mRNA expression was generally much greater from the 3betaHSD than from the 17betaHSD gene. Furthermore, fat androstenone was negatively correlated with liver 3betaHSD gene expression (Pearson correlation, r = -0.69; P < 0.05), and the 17betaHSD gene expression in liver was negatively correlated with plasma E1S (r = -0.95; P < 0.001), indicating an important role of liver 17betaHSD in the estrogen metabolism of gonadally intact male pigs. Another strong correlation was found between 3betaHSD and 17betaHSD gene expression in liver of the gonadally intact male pigs (r = 0.86; P < 0.01), possibly reflecting similar regulation mechanisms of these genes.

The effect of Human chorionic gonadotropin (hCG) stimulation on the concentrations of free and conjugated androstenone in plasma was studied in 34 crossbred entire male pigs (Landrace x Swedish Yorkshire). Seventeen pigs were treated with hCG 4 days prior to slaughter and the remaining pigs were treated with sterile saline and served as controls. Blood samples were taken prior to hCG or saline injection and on the day before slaughter and analysed for concentrations of free and conjugated androstenone. Testicular tissue samples were taken at slaughter and analysed for the levels of cytochrome b5 (cyb5) protein. Here we have demonstrated for the first time that hCG stimulation causes an increase in the plasma levels of both free and conjugated androstenone. Not all animals responded in the same way to hCG treatment regarding levels of free and conjugated androstenone demonstrating that individual animals can have differences in their capacity to produce free and conjugated androstenone. We suggest that hCG treatment is a good way to determine the potential for androstenone conjugation when androstenone synthesis in the testis is high. The levels of cyb5 protein in the testis were slightly related (r=0.41, p < 0.10) to free androstenone levels in the pigs after hCG administration, although levels of cyb5 protein were not affected by hCG treatment.

We report the identification of quantitative trait loci (QTL) affecting carcass composition, carcass length, fat deposition and lean meat content using a genome scan across 462 animals from a combined intercross and backcross between Hampshire and Landrace pigs. Data were analysed using multiple linear regression fitting additive and dominance effects. This model was compared with a model including a parent-of-origin effect to spot evidence of imprinting. Several precisely defined muscle phenotypes were measured in order to dissect body composition in more detail. Three significant QTL were detected in the study at the 1% genome-wide level, and twelve significant QTL were detected at the 5% genome-wide level. These QTL comprise loci affecting fat deposition and lean meat content on SSC1, 4, 9, 10, 13 and 16, a locus on SSC2 affecting the ratio between weight of meat and bone in back and weight of meat and bone in ham and two loci affecting carcass length on SSC12 and 17. The well-defined phenotypes in this study enabled us to detect QTL for sizes of individual muscles and to obtain information of relevance for the description of the complexity underlying other carcass traits.

This study aimed to describe the association between incidence of boar taint and pubertal changes in gonadal hormones, size of reproductive organs and aggressive behaviour in entire male pigs. In total, 111 entire male pigs were included in the study. Sampling was performed first at 90 kg live weight (LW) and, then, at 115 kg LW. Variables measured were skatole and androstenone levels in plasma and fat, testosterone and oestrone sulphate in plasma, free oestrone in fat, weight of testes and length of bulbourethral glands. Aggressive interactions between pigs were registered when a limited amount of feed was provided to the pigs prior to routine feeding. The number of initiated interactions (attacks) and the difference between number of initiated and received interactions (relative attacks) were calculated for each pig. Multivariate analysis revealed that gonadal hormones and reproductive organ size influenced prevalence of boar taint, accounting for 30% of the variation in skatole levels in fat and for 37% of the variation in androstenone levels in fat. These relations were independent of aggression levels in entire male pigs. Skatole levels were influenced by the levels of oestrone sulphate in plasma and free oestrone in fat, but not levels of plasma testosterone. Pigs with testes weight below 565 g and a bulbourethral gland length <90 mm did not produce high amounts of skatole; therefore, these values can be used as a threshold level to detect pig carcasses with low skatole levels. High androstenone levels could not be predicted by measuring reproductive organ sizes. More research is required to develop a rapid and accurate method for the analysis of carcasses of entire male pigs.

Relationship between free oestrone and boar taint compounds in adipose tissue were studied in two groups of entire male pigs of different breeds. Group A consisted of 33 entire crossbred male pigs (dam Yorkshire and sire backcross Yorkshire x Wild Boar, generation seven). Group B consisted of 194 entire male pigs of crossbreeds between Swedish Hampshire (H) and Finnish Landrace (L), LH x H, H x LH, LH x LH (dam x sire). The measurements of free oestrone in adipose tissue were performed with a new method developed and validated in our laboratories. The standard curve was linear for concentrations of free oestrone ranging from 0.13 to 5.10 ng/g. The method exhibited parallelism of results between serial dilutions and a mean recovery of 97 +/- 13.7%. Intra-assay variations for samples with concentrations of free oestrone from 0.67 to 2.08 ng/g were from 9.23 to 11.94%. Inter-assay variations for the samples with concentrations of free oestrone from 0.89 to 2.96 ng/g were from 3.78 to 10.11%. The levels of free oestrone in fat from group A were well correlated with fat levels of androstenone (r = 0.66; p < 0.001) and levels of oestrone sulphate in peripheral plasma collected at the same time as the fat (r = 0.74, p < 0.001). The levels of free oestrone in fat from group B were significantly correlated to fat levels of androstenone (r = 0.68, p < 0.001) and skatole (r = 0.29, p < 0.001). In group B, age-related differences in fat levels of free oestrone, androstenone and skatole were studied. Free oestrone and skatole levels increased simultaneously at the age of 22 week (p < 0.05 for both), and androstenone levels increased at the age of 26 week (p < 0.05). It was suggested that the levels of free oestrone in adipose tissue might be used for the evaluation of hormonal status of male pigs as an alternative to plasma levels of testicular hormones. The levels of free oestrone might be involved in the regulation of skatole levels in fat as indicated by both the simultaneous increases in skatole and free oestrone levels in fat and positive correlation between skatole and free oestrone.

This study describes the age-related variation in boar taint compounds, skatole and androstenone, and testosterone, oestradiol-17 beta (E17 beta), oestrone sulphate (ES), dehydroepiandrosterone sulphate (DHEAS), triiodothyronine (T(3)) and insulin-like growth factor-1 (IGF-1) in six boars. Three pairs of littermates of crossbred entire male pigs (from three Yorkshire x Duroc dams and one Hampshire sire) were included. Blood samples were taken at the age of 9-15 weeks and thereafter at weekly intervals from the age of 20-32 weeks. Plasma concentrations of skatole, androstenone, testosterone, E17 beta, ES, DHEAS, T(3) and IGF-1 were measured. We found that skatole levels in boars increased at the age around puberty after an increase in the levels of testicular steroids. Levels of skatole were not associated with the levels of sex steroids, T(3) and IGF-1. However, the increased level of testicular steroids is probably the underlying factor needed for high skatole levels to occur although the specific mechanism leading to increased skatole levels remains unknown.

Pig meat shows natural variations in the concentrations of precursors of heterocyclic amines (HCAs), which may affect formation of HCAs in cooked pig meat. To study this, 26 pigs with an inherent genetic variation (carriers and noncarriers of the RN(-) allele) were subjected to different feeding regimes (conventional feed compared with feed composed according to organic standards). In addition, the effect of sex (castrated males or females) was considered when assessing chemical and technological meat quality parameters. Concentrations of precursors of HCAs, i.e., creatine, residual glycogen, dipeptides, and free amino acids, were analyzed in the raw meat, and the levels of some HCAs (4,8-DiMeIQx, MeIQx, PhIP, harman, and norharman) were then determined in fried meat patties prepared from these pigs. The RN genotype most affected technological meat quality parameters and the level of precursors of HCAs, especially the level of residual glycogen, where carriers of the RN(-) allele showed levels four times as high as those of noncarriers (75.3 +/- 2.6 compared with 17.2 +/- 2.4 micromol/g meat, least-squares means +/- SE). The increased level of residual glycogen resulted in about 50% lower amounts of total mutagenic HCAs in cooked meat compared with cooked meat from normal pigs. Fried meat from carriers of the RN(-) allele obtained darker crust color than meat from noncarriers. Feeding regime and sex did not significantly affect the chemical composition of the meat or the formation of HCAs.

A study was conducted to elucidate the effects of social factors on the concentrations of boar taint substances, androstenone and skatole, in boars. The factors included dominance (social rank) and the effects of strongly tainted animals on other members of the group. Four successive replicates of 100 pigs (50 boars + 50 gilts) with an average live weight of 24 kg were randomly allocated to 10 pens of 10. Data for this study were collected during the period of 67 to 114 kg of live weight and included the repetitive recording of agonistic behavior during competitive feeding; blood sampling for determination of plasma androstenone, skatole and testosterone in boars; feces sampling for determination of skatole content; and collection of bulbourethral glands in boars, and uteri plus ovaries in gilts at slaughter, for the assessment of sexual maturity. Results show an influence of social rank on plasma concentrations of androstenone (P = .0001) and testosterone (P = .0001), the weight of the bulbourethral glands (P = .0001), and plasma skatole (P = .02). Pens were classified according to the pig with the highest concentration of androstenone in the pen into high, medium, and low maximum pens. In pens with high maximum concentrations of androstenone, the second-highest androstenone concentration (P = .0001), and the average concentration (P = .0003) in the pen were higher than those in pens with medium or low maximum concentrations of androstenone. Mean aggression level was also higher (P = .02), but pens with high maximum aggression level did not have higher mean androstenone concentration. Rank effect on androstenone was more important than aggression effect. Neither maximum androstenone concentration nor maximum aggression level in a pen was related to the pen mean stage of sexual maturity in either sex. No influences of rank, aggression, or aggression received were found on the feces skatole level, and no pheromonal communicative function was demonstrated for skatole. High androstenone concentrations did not have a suppressive effect on androstenone concentrations in other males of the group; on the contrary, the levels were increased. This may be due to a stimulating effect of androstenone and, possibly, mating activity. Consequently, in the production of boars for slaughter, strongly tainted animals should be avoided or removed and mating activity minimized. This could be facilitated by, for instance, slaughtering before sexual maturity or separate rearing of the sexes.

The relationship between the metabolism of androsterone and skatole, the major compounds responsible for boar taint, was investigated in F4 Swedish Yorkshire x European Wild Pig intact males. The metabolism of androstenone and skatole were studied in liver microsomes, and the testicular steroid production was measured in testes microsomes. Including androstenone in the assays of skatole metabolism reduced the formation of 6-hydroxyskatole (pro-MII), and three other skatole metabolites (P<.05). The formation of three additional metabolites was not affected. Liver microsomal incubations of androstenone produced two metabolites, I and II. The rate of the formation of metabolite I and the rate of androstenone metabolism were correlated with the rate of skatole metabolism. Liver metabolism of androstenone was not related to levels of androstenone in fat. Testicular synthesis of 16-androstene steroids was correlated with combined synthesis of estrogens and androgens, plasma levels of androstenone, levels of skatole in fat, and skatole metabolism in the liver (P<.05). Plasma levels of estrone sulfate were correlated with levels of skatole in fat and with androstenone levels in fat and plasma and were negatively correlated with synthesis of skatole metabolite F-1 and pro-MII sulfation. These results indicate that the liver metabolism of androstenone and skatole are related. However, it is likely that the relationship between levels of androstenone and skatole in fat is due more to a link between the testicular synthesis of androstenone rather than to the metabolism of androstenone and skatole in the liver. Sex steroids may affect this relationship because of their biosynthesis along with androstenone and possible inhibition of skatole metabolism in the liver.

Forty-eight weaned, winter-born crossbred males (average age of 42 days) were exposed to either a natural photoperiod (January-June at 60 degrees N, Control) or one of two artificial photoperiods (1400 lx) in light-sealed rooms. The Spring/Summer group was exposed to an artificial photoperiod simulating conditions from the vernal equinox (mid-March) to August at 60 degrees N and the Autumn/Winter group to a photoperiod, simulating conditions from the autumnal equinox (mid-September) to February at 60 degrees N. Plasma samples were collected biweekly until the pigs were slaughtered, after reaching 115 kg, and analysed for testosterone, estrone sulfate, thyroxine and prolactin. Additionally, three animals per treatment (n = 9) were injected with gonadotropin-releasing hormone (GnRH) and plasma samples were collected every 15 min and analysed for luteinizing hormone and testosterone. Boar taint, carcass composition and reproductive traits were measured at slaughter. Live-weight gain from start to slaughter was lower among the Control animals compared with the Autumn/Winter and Spring/Summer animals. There was a peak in plasma testosterone in both the Spring/Summer and Autumn/Winter groups at 71 days of age, whereas plasma testosterone in the Control group remained at prepubertal levels. At 113 and 127 days of age, the Control group had somewhat higher testosterone levels than the Spring/Summer group, but at 141 days of age and on the day before slaughter, the Autumn/Winter group had a higher mean plasma testosterone concentration. There were no differences between treatments in the endocrine response to the GnRH challenge. Bulbourethral gland weight at slaughter was lower in the Spring/Summer group than in the Autumn/Winter group. The percentage of proximal cytoplasmic droplets was higher in the Spring/Summer group than in both the Control and Autumn/Winter groups. Spermatogenesis at the time of slaughter was clearly more mature in animals in the Autumn/Winter group than in those in the Spring/Summer and Control groups. Fat androstenone was lower in the Spring/Summer group than in the Control group. In the sensory evaluation, the Spring/Summer group had less boar taint than the Autumn/Winter group. Artificial short days with moderate initial changes in photoperiod, stimulated spermatogenesis compared with long days, in accordance with the pattern seen in European Wild Boars (Sus scrofa). Boar taint was also affected with higher scores in the Autumn/Winter group than in the Spring/Summer group, although this was not clearly indicated by the traditional measurements of boar taint-fat contents of androstenone and skatole.

A quantitative trait locus (QTL) analysis of growth and fatness data from a three generation pig experiment is presented. The population of 199 F2 animals was derived from a cross between wild boar and Large White pigs. Animals were typed for 240 markers spanning 23 Morgans of 18 autosomes and the X chromosome. A series of analyses are presented within a least squares framework. First, these identify chromosomes containing loci controlling trait variation and subsequently attempt to map QTLs to locations within chromosomes. This population gives evidence for a large QTL affecting back fat and another for abdominal fat segregating on chromosome 4. The best locations for these QTLs are within 4 cM of each other and, hence, this is likely to be a single QTL affecting both traits. The allele inherited from the wild boar causes an increase in fat deposition. A QTL for intestinal length was also located in the same region on chromosome 4 and could be the same QTL with pleiotropic effects. Significant effects, owing to multiple QTLs, for intestinal length were identified on chromosomes 3 and 5. A single QTL affecting growth rate to 30 kg was located on chromosome 13 such that the Large White allele increased early growth rate, another QTL on chromosome 10 affected growth rate from 30 to 70 kg and another on chromosome 4 affected growth rate to 70 kg.

To determine if artificial light regimens could influence sexual maturation and boar-taint factors in entire male pigs, 48 weaned, winter-born crossbred males (52-64 days old) were exposed to either a natural photoperiod (January-June, 60 degrees N, Control, n= 16) or to one of two artificial photoperiods (1400 1x) in light-sealed rooms. We exposed the Spring group to an increasing artificial photoperiod (January - June, 60 degrees N, n=16) and the Autumn group to a decreasing one (July-December, 60 degrees N, n = 16). Plasma samples were collected bi-weekly until the pigs were slaughtered, after reaching 115 kg. Boar taint, carcass composition and reproductive traits were measured at slaughter. Plasma testosterone increased earlier in the Autumn group than in the Control and Spring groups, but the difference was only transient. Estrone sulfate concentrations remained low in the Autumn group, whereas they increased in the Control and Spring groups, indicating a lack of synchrony between testicular androgen and estrogen production in the Autumn group. In the beginning of the study, when the Autumn group was subjected to long days, plasma prolactin was higher in the Autumn group than in the Spring group, but the relation was reversed 14 weeks later when the spring group was exposed to long days. Weight of reproductive organs (epididymidal weight and the total weight of the testes, epididymides and the bulbourethral glands relative to carcass weight) were lower in the Autumn and Spring groups than in the Control group. The Spring and Autumn groups had lower concentrations of skatole in fat compared with the Control group, whereas no clear difference was detected between groups in concentrations of androsterone in fat or in the sensory evaluation of boar taint. Estimated lean meat percentage was lower among animals in both the Autumn and Spring groups compared with the Control group. This study shows that photoperiod can influence male pubertal development and boar-taint factors in the domestic pig.

An intercross between wild boar and a domestic Large White pig population was used to map quantitative trait loci (QTL) for body proportions, weight of internal organs, carcass composition, and meat quality. The results concerning growth traits and fat deposition traits have been reported elsewhere. In the present study, all 200 F2 animals, their parents, and their grandparents were genotyped for 236 markers. The marker genotypes were used to calculate the additive and dominance coefficients at fixed positions in the genome of each F2 animal, and the trait values were regressed onto these coefficients in intervals of 1 cM. In addition, the effect of proportion of wild boar alleles was tested for each chromosome. Significant QTL effects were found for percentage lean meat and percentage lean meat plus bone in various cuts, proportion of bone in relation to lean meat in ham, muscle area, and carcass length. The significant QTL were located on chromosomes 2, 3, 4, and 8. Each QTL explained 9 to 16% of the residual variance of the traits. Gene action for most QTL was largely additive. For meat quality traits, there were no QTL that reached the significance threshold. However, the average proportion of wild boar alleles across the genome had highly significant effects on reflectance and drip loss. The results show that there are several chromosome regions with a considerable effect on carcass traits in pigs.

The frequency of the dominant RN- allele (Rendement Napole) was estimated in purebred Swedish Hampshire pigs (n = 208) by using the estimated glycogen content in the longissimus muscle at slaughter (glycolytic potential; GP). Carriers (n = 177) and noncarriers (n = 31) of the RN- allele were compared with purebred Swedish Yorkshire (Y, n = 208) and Swedish Landrace (L, n = 114) pigs with respect to GP and carcass composition. Technological meat quality was compared between the RN phenotypes from the Hampshire breed and Yorkshire pigs. The distribution of GP deviated from a normal distribution in all three breeds. Hampshire pigs with GP > or = 183 micromol lactate equivalents per gram wet weight were regarded as carriers of the RN- allele (RN-/RN-, or RN-/rn+), and those constituted 85% of all Hampshire pigs evaluated, giving a frequency of .61 for the dominant allele (RN-). The RN- carriers had higher GP than noncarriers, Landrace, and Yorkshire pigs, but noncarriers and Landrace did not differ regarding GP. The two RN phenotypes did not differ in carcass composition, but the carriers were leaner than Landrace and Yorkshire, with larger proportions of meat plus bone in ham and back. Noncarriers and Yorkshire did not differ in leanness, but both these groups were leaner than Landrace. The RN- carriers had lower Napole yield (cured cooked muscle) and higher drip loss than noncarriers and Yorkshire, but in comparison with noncarriers they also had lower shear force values. In conclusion, the frequency of the RN- allele is high in purebred Swedish Hampshire. Most of the effects of the allele on technological meat quality (i.e., ultimate pH, water-holding capacity, and technological yield) found in crossbred pigs seem also to be consistent for purebred pigs. However, the RN- allele exerted less influence on meat content in purebred pigs.

The relationships between levels of skatole and androstenone in fat, plasma levels of skatole metabolites, plasma testosterone and estrone sulfate, and levels of cytochrome P450IIE1 in liver were investigated in Swedish Yorkshire pigs and F4 Wild Pig crosses. Levels of skatole, the skatole metabolite MIII, and androstenone were higher in males from the Wild Pig crosses than in the Yorkshire pigs. Plasma levels of the skatole metabolite MII and the ratio between MII and MIII were higher in female Yorkshire pigs than in male pigs. Skatole was correlated with androstenone, cytochrome P450IIE1, and estrone sulfate in the Wild Pig crosses but not in Yorkshire pigs. However, plasma levels of skatole metabolites were not correlated to levels of cytochrome P450IIE1 in liver in either group on animals. Pigs with high levels of cytochrome P450IIE1 in liver had low levels of skatole in fat, and pigs with low levels of cytochrome P450IIE1 in liver had low and high skatole levels. Using stepwise regression analysis, only levels of cytochrome P450IIE1 in liver significantly explained the variation in skatole levels in the Wild Pig crosses. Our results support the hypothesis that low levels of cytochrome P450IIE1 in liver may result in high levels of skatole in backfat of uncastrated male pigs due to decreased metabolism and clearance of skatole. However, these pigs cannot be identified based on plasma levels of skatole metabolites MII and MIII.

The relationship between the histochemical and biochemical properties of muscle and the quality of meat during selection to improving the lean tissue growth rate was studied. Pigs (n = 82) from Generations 2 and 4 were randomly sampled in a selection experiment in which the genotype x protein interaction was studied. Comparisons were made of longissimus muscle (LM) and quadriceps femoris (QF) from Generations 2 and 4, and biceps femoris (BF) in the fourth generation from pigs fed a low- or high-protein diet. A higher total growth rate, lean tissue growth rate, and lean percentage were found in pigs fed the high-protein diet than in pigs fed the low-protein diet. Pigs fed the high-protein diet had a higher glycolytic capacity in all muscles than pigs fed the low-protein diet. When the meat quality traits were compared, pigs fed the high-protein diet had a lower intramuscular fat content, higher shear force value, higher protein extractability, lower light reflectance, and somewhat higher water-holding capacity. With selection, pigs became fatter on both diets. In Generation 4, glycolytic and oxidative capacity was somewhat higher in muscle tissue than in Generation 2. Muscle metabolic profile and meat quality traits differed among muscles (LM, BF, QF) but no pronounced differences were found between generations. No marked changes were observed in Type I, IIA, or IIB fibers, either between diets or between generations. The Type IIC fibers could only be identified in Generation 4.

The presence of free androgen and glucocorticoid receptors was demonstrated in the rectus femoris muscle of the pig. No detectable free androgen receptors were observed in intact male pigs. Androgen receptor characteristics in castrates and gilts were related to the growth rate of the lean meat in the ham. The amount of free androgen receptor was less (P less than .05) and the androgen was more tightly bound to its receptor (P less than .05) in pigs with above-average ham growth. Moreover, a higher DNA content (P less than .01) was also found in these pigs, giving a lower (P less than .05) protein to DNA ratio. The anabolic action of androgens is likely to be mediated via androgen receptors in skeletal muscle cytosol. The amounts of free glucocorticoid receptors found were influenced by the pH of the cytosolic fraction. The relationships between cytosolic pH and both the amount of glucocorticoid receptor (positive; P less than .01) and plasma levels of cortisol (negative; P less than .05) might reflect the stress to which the pigs are exposed at slaughter.

The antibody response to two Escherichia coli antigens (O149 and K88) and the in vitro reactivity of peripheral blood lymphocytes (PBLs) to pokeweed mitogen was studied in growing pigs after exposure to varying degrees of stress. Three experimental groups were used; transportation by lorry, transportation by lorry after a previous injection of a tranquillizing drug (amperozide), no transportation but an amperozide injection. Another group was used as a control group. This group was not transported and received no amperozide injection. The animals were the offspring of boars and sows heterozygous (Nn) for the Hal gene, and all 3 Hal genotypes (NN, Nn, nn) were identified and could thus be compared within litters. Immediately after the experimental treatment, the highest PBL reactivity was found for the amperozide-treated animals and for the non-transported animals, with no differences in reactivity between Hal genotypes. Two weeks later, the treatments caused different effects on pigs of the 3 Hal genotypes, both with regard to the PBL reactivity and the IgG response to O149. The NN pigs had a higher PBL reactivity than the nn pigs for all treatments except the 'drug + transport' class where the reverse rank order was found. The NN pigs also had a higher IgG response to O149 than the nn pigs in the 'drug + no transport' class. The amperozide treatment was followed by a higher PBL reactivity in non-transported NN pigs and in transported nn pigs. The amperozide-treated non-transported NN pigs also had a higher IgG response to O149. The highest PBL reactivity and IgG response to O149 were found mainly in pigs with the lowest cortisol levels. Pronounced differences between litters were found for both the antibody response and the PBL reactivity.

Effects of stress on concentrations of cortisol and corticosteroid-binding globulin (CBG) in blood plasma and on glucocorticoid receptor concentrations in muscle cytosol were studied in pigs representing three Halothane (Hal) genotypes (NN, Nn, nn). At 12 wk of age, animals were divided into four groups: pigs subjected to transport (5 h in a truck), pigs treated with amperozide prior to transport, pigs not transported but treated with amperozide and pigs neither transported nor given amperozide. Animals were slaughtered the week they reached 100 kg live weight (3 mo later). The Hal gene showed no major influence on the variables studied except for cortisol concentrations (P = .06) measured directly after transport at 12 wk of age (NN = 66.8 nM, Nn = 61.4 nM, nn = 69.4 nM). However, the response in each Hal genotype differed, depending on whether or not the pigs had been exposed to transport. Two weeks after transport, NN pigs developed higher cortisol concentrations than untransported animals, whereas the response was reversed in nn animals; Nn pigs showed no difference in this regard. At slaughter, the effect of transport (12 wk of age) on cortisol and CBG was still apparent. In NN pigs cortisol and CBG concentrations were elevated (P less than or equal to .05, P = .08, respectively), whereas concentrations tended to be lower in nn pigs (P = .17, P = .07, respectively) when compared with untransported pigs. Transported pigs had lower receptor concentrations at slaughter (P less than or equal to .01) than untransported pigs. However, pigs given amperozide in connection with transport had a receptor concentration comparable to that in untransported pigs. Our study shows conclusively that transport stress had long-term effects on cortisol, CBG and glucocorticoid receptor concentrations. In addition, amperozide had long-term effects on cortisol and receptor concentrations.

The aim of this study was to evaluate the effectiveness of a gonadotropin-releasing hormone (GnRH) vaccine, Improvac™ (Pfizer Ltd), in suppressing aggressive and sexual behaviour of male pigs. One hundred and thirty-six pigs were assigned to three treatments: entire male pigs (n=64), immunocastration against GnRH (n=48) and surgical castration (n=24). Surgical castration was performed before the age of 1 week. Vaccination comprised two injections: the first injection was given 8 to 11 weeks before slaughter and the second injection 4 weeks before slaughter. After the second injection, immunocastrated pigs showed less non-violent social and aggressive behaviours than entire male pigs of the same age. Mounting was reduced to the same low level as observed in surgically castrated pigs, and more immunocastrated pigs were without skin lesions compared with entire male pigs. Pigs that received the second injection only 1 week before the observation day did not differ significantly in behaviour from those that received the injection 3 weeks before the observation day. Thus, the behaviour seems to change soon after the second injection and these changes remain until slaughter. [ABSTRACT FROM AUTHOR]

PIGCAS (Attitudes, practices and state of the art regarding piglet castration in Europe) is to our knowledge the first project that has focused on castration practice across European countries (European Union minus Bulgaria, Malta and Romania, plus Norway and Switzerland). About 250 million pigs are slaughtered in Europe each year. Of the 125 million male pigs, approximately 20% are left entire, less than 3% are castrated with anaesthesia and the rest is castrated without anaesthesia. The study identified large variations in castration procedures, both within and between countries. In females, castration is very rare, but is practiced without anaesthesia in special breeds/production systems in some of the southern countries. [ABSTRACT FROM AUTHOR]

This paper constitutes an updated review of the production and meat quality aspects of rearing entire male pigs. Since a major obstacle in rearing entire males is the incidence of boar taint, possible methods for detection are also summarised. Safe and fast methods for detection of boar taint would be valuable in avoiding complaints from consumers. Pig meat quality is determined by many aspects, among which odour and taste are the most important attributes. Odour may be negatively affected by the presence of a pheromonal steroid, androstenone, and a fermentation product of L-tryptophan, skatole. Male pigs are surgically castrated in many countries to minimise the risk of accumulation of high levels of androstenone and skatole. Raising entire male pigs is more profitable because they have superior production characteristics and improved meat quality due to leaner carcasses and higher protein content, as compared to castrated pigs. Furthermore, surgical castration is negative from an animal welfare point of view. In most studies, no differences in sensory quality have been found between lean meat from entire male pigs with low levels of androstenone and skatole and pork from castrates and females. The question that remains is: which substances are responsible for boar taint besides androstenone and skatole and whether they need to be considered? The threshold values used for androstenone and skatole might also be too high for highly sensitive persons. Recent research shows that a human odorant receptor, ORD7D4, is involved in sensitivity to androstenone. If the ORD7D4 genotypes of consumer and expert panels are known, this might facilitate consumer studies in the future. There is still a great need for rapid on/at-line detection methods in abattoirs for identifying carcasses with unacceptable levels of boar taint compounds. Several emerging rapid technologies with a potential for boar taint detection have been investigated. They represent various measurement principles such as chemical sensor arrays (electronic noses), mass-spectrometry fingerprinting, ultra-fast gas chromatography, gas-phase spectrometry and biosensors. An industrial detection method should allow 100% correct classification of both acceptable and not-acceptable samples with regard to boar taint sorting criteria. There are, however, still too high a percentage of false negatives ranging from 5% to 20%. In addition, these methods do not yet seem to fulfil the industrial specifications with regard to cost efficiency, simplicity and analysis time. There is still no dedicated measurement technology available for on/at-line detection of boar-tainted carcasses that measures both androstenone and skatole. [ABSTRACT FROM AUTHOR]

Contents The objective of this study, comprising two trials, was to evaluate the effect of a gonadotropin-releasing hormone (GnRH-vaccine ImprovacTM; Pfizer Ltd) in a sample of the Swedish pig population. The pigs (n = 120) were assigned to three groups: control (entire male pigs), surgical castration and immunization against GnRH. Surgically castrated pigs did not express detectable levels of either testosterone or estrone sulphate (E1S) in plasma, or androstenone in fat and had lower skatole and indole levels in fat than entire male pigs. Immunization significantly reduced testes weight and bulbourethral gland length, plasma levels of the testicular hormones testosterone and E1S, and fat levels of androstenone, skatole and indole. Skatole levels in plasma were significantly lower than in entire male pigs in the second trial, but not in the first due to overall low skatole levels. All immunized pigs and surgically castrated pigs expressed skatole concentrations in fat below the level of 0.2 μg/g, above which meat is regarded as tainted. In contrast, eight entire male pigs exceeded this level. Indole levels in plasma from immunized pigs were lower than those from entire male pigs. Surgical castration caused lower daily weight gain in the suckling period compared with piglets raised intact, whereas in the post-weaning period no difference was observed. Immunization resulted in higher feed intake and daily weight gain after the second injection. The estimated lean meat content was improved in comparison with the castrated pigs, but was lower than for entire male pigs. Dressing percentage was lower in immunized pigs than in surgically castrated and entire male pigs. The frequency of skin damage did not differ between immunized and entire male pigs or between immunized and surgically castrated pigs. [ABSTRACT FROM AUTHOR]

Aggressive and sexual behaviour in entire males and females were studied on 408 pigs. The sum of aggressive interactions in the pen during routine feeding (ALP) was lowest in single-sex pens with females. ALP was higher at 132 than at 155 days. High ALP correlated with high average growth rate. Aggressive interactions in a competition test (IA) increased after slaughter of the three fastest-growing pigs in a pen (at 155 days), although the slaughtered pigs had initiated the most IA earlier (at 132 days). Entire male pigs displayed more sexual behaviour (mounting) than females. In 15% of entire males and 6% of females there were health problems specifically involving lameness or injured legs or feet. Five entire males and one female were euthanized in response to lameness or leg fracture. The rearing of entire male pigs may cause welfare problems, given their higher levels of aggression and sexual behaviour. [ABSTRACT FROM AUTHOR]

The influence of differentiated extra maternal feed allowance during early gestation on maternal performance and postnatal development of the progeny from gilts and sows was investigated. Four different feed allowances of the same diet (Control [C], +35% [T35], +70% [T70], +100% [T100]) were assigned to 20 crossbred gilts (Swedish Landrace×Swedish Yorkshire), which continued as sows with the same feed allowance the following parity. The progeny was uniformly raised and slaughtered at a live weight of 110 kg. Additional maternal feed allowance resulted in significantly more weaned piglets per sow but not per gilt. Piglet numbers did not increase from T35 to T70/T100. Piglet birth weight did not increase due to maternal feeding. The intra-litter variation in piglet birth weights was similar between the treatments. Independent of the additional feed allowance, all gilts and sows had similar weights after weaning and had good body condition. The growth rate of progeny from sows was negatively related to maternal feed supply; for progeny from gilts, no clear trend of nutritional influence could be observed. Carcass and technological meat quality was not affected by maternal feeding treatment. Birth weight positively affected later growth performance (daily weight gain), carcass quality (lean meat content, back fat, proportion of muscles in ham/loin), whereas technological meat quality was unaffected. [ABSTRACT FROM AUTHOR]

The objective of the study was to compare production results and technological meat quality for pigs born outdoors and reared indoors or outdoors during the summer period. A total of 279 pigs was reared in a large pen on deep litter, or outdoors. Daily weight gain and lean meat percentage were higher for pigs outdoors than indoors during year one (864 vs. 841g; 56.9 vs. 55.9%), but were similar for year two (859 vs. 844g; 55.9 vs. 55.6%). Outdoor pigs grew faster when fed ad libitum , but slower during the second phase when restricted, with inferior feed conversion. Most technological meat quality traits (surface and internal reflectance, marbling, pH BF , filter paper wetness, cooking loss and maximal Warner-Bratzler shear force) were similar between rearing systems, whereas pH LD was higher indoors. Total work of Warner-Bratzler shear force was lower in outdoor reared pigs. Maternal sire breed (Duroc or Landrace) and sex (castrate or gilt) did not notably affect meat quality traits. RN genotype had a stronger impact on meat quality than rearing system. It can be concluded from the similarities in production results and meat quality in both systems, that both indoor and outdoor rearing are good alternatives for summer rearing of pigs. [ABSTRACT FROM AUTHOR]

Abstract: Cytochromes P4502E1 (CYP2E1) and P4502A6 (CYP2A6) catalyse metabolic reactions of skatole and indole metabolism. The objectives of this study were as follows: to evaluate whether activities of CYP2E1 and CYP2A6 in pigs of two live weights (LW) differ between males and females; to investigate whether activities of CYP2E1 and CYP2A6 are affected by hCG stimulation; and to investigate whether the levels of skatole and indole in the liver and the activities of CYP2E1 and CYP2A6 are affected by raw potato starch (RPS). Female pigs expressed higher CYP2A6 activity at 90kg LW, and higher CYP2E1 activity at 115kg LW compared to male pigs. Skatole levels in the liver were higher in male pigs than in female pigs at both LW, whereas indole levels were higher in males only at 115 kg LW. Neither levels of indolic compounds in the liver nor enzyme activities were affected by hCG stimulation. The inclusion of RPS in the diet reduced skatole levels in the liver in both sexes and increased CYP2A6 activity in female pigs. It was concluded that the incidence of boar taint may depend on both skatole amount, which reach the liver, and the activities of enzymes involved in skatole metabolism, which may vary depending on sex, live weight, and diet. [Copyright &y& Elsevier]

Abstract: Our objective was to evaluate pigs injected with human chorionic gonadotropin (hCG) as a potential model to study the effect of high testicular steroid levels on the variation in indolic compounds. Pre-selection of the sires based on their plasma skatole levels was used, to evaluate whether the response to hCG would be affected. Out of 34 entire male pigs, 17 pigs were injected with hCG and the remaining pigs were injected with sterile saline four days prior to slaughter. HCG injection increased the levels of testicular steroids (androstenone, testosterone, dehydroepiandrosterone sulphate, oestrone sulphate and oestrone; p <0.001), and indole levels in plasma and fat (p <0.05). Skatole levels in fat increased slightly but not significantly (p =0.107), whereas skatole levels in plasma were not affected. The correlation coefficients between androstenone and skatole levels in fat were 0.54 in the hCG-injected group and non-significant in the control group. Skatole levels in fat were not correlated with testicular steroids in either hCG-injected pigs or controls. Skatole and indole levels in fat were positively correlated in both groups. We concluded that hCG-injected pigs might be useful for studying factors responsible for the role of testicular steroids in the occurrence of high indole levels. Pre-selection of sires based on plasma skatole levels affected both the levels of indolic compounds and testicular steroids, especially in fat, which might have suppressed the response to hCG. Whether hCG affects skatole or not is therefore not fully elucidated. [Copyright &y& Elsevier]

Abstract: This study evaluated the effect of supplement of raw potato starch (RPS) on the levels of skatole, androstenone, testosterone and oestrone sulphate in plasma from entire male pigs. The study also evaluated relationships between plasma levels of skatole and testicular steroids at three different live weights (LW) of approximately 90, 100 and 115 kg. A total of 111 entire male pigs of a crossbred (Yorkshire dams×Swedish Landrace sires) were used. Animals were raised either in mixed pens, with females and males, or single-sex pens. Each pen contained seven or nine pigs. The most fast-growing three pigs from the pens with nine pigs were slaughtered when they reached 90 kg LW, and the remaining pigs were slaughtered at 115 kg LW. All pigs were fed the same commercial diet until the average pen weight reached 100 kg. Then, 33 out of 80 remaining pigs received RPS, 0.6 kg per pig and day, for 2 weeks prior to slaughter. Blood samples were taken from the pigs at three occasions: first, the day prior to first slaughter occasion, low-weight group; second, the day prior to change in diet, middle-weight group; and third, the day prior to second slaughter occasion, high-weight group. Plasma was analysed for the levels of skatole, androstenone, testosterone and oestrone sulphate. Fat samples were taken at slaughter and analysed for the levels of skatole and androstenone. The levels of skatole and testicular steroids in plasma were significantly higher in entire male pigs from the high-weight group fed no RPS compared to those from low- and middle-weight groups. The levels of the investigated compounds did not differ between low- and middle-weight groups (P>0.1). The diet with RPS induced a decline in skatole levels in plasma and fat (P&#60;0.001), but not plasma levels of testicular steroids and fat levels of androstenone (P>0.05). Skatole levels were positively correlated to testosterone and oestrone sulphate levels in the middle- and high-weight pigs fed no RPS as well as to testosterone in the low-weight group. In the high-weight group fed RPS, skatole levels were not correlated to any of the analysed compounds. Approximately 26% of the entire male pigs (11 out of 43) from the high-weight group fed no RPS produced skatole levels in fat above 0.20 μg/g, whereas the pigs from the low- and high-weight group fed RPS did not produce skatole levels above 0.20 μg/g in fat. Androstenone levels in fat were high in all groups. In total 47% (52 out of 111) pigs expressed androstenone levels above the rejection levels in fat of 1.0 μg/g and 88% (98 out of 111) had androstenone levels above 0.5 μg/g. It was concluded that a lower slaughter weight and the supplement of raw potato starch to the diet could be used to reduce skatole levels in entire male pigs. Androstenone levels in fat, however, could not be reduced by either a lower weight at slaughter or dietary manipulation. [Copyright &y& Elsevier]

High skatole and to a lesser degree indole levels in some entire male pigs result in occurrence of off-flavor in meat, called boar taint. In this study, plasma samples from 117 Yorkshire, 134 Landrace, 184 Hampshire and 75 Duroc entire male pigs collected at different ages were analyzed for skatole and slightly fewer samples for indole concentrations. For each breed, a distinct age-related distribution of plasma skatole levels was observed. Skatole levels were increased at approximately 180–200 days of age, reaching very high levels is some individuals. Afterwards, the levels decreased; in Yorkshire and Landrace at approximately 240–260 and in Hampshire and Duroc at 310–360 days of age. The decrease of skatole levels was also observed in samples collected from 15 Landrace boars at two different ages: 16.8 μg/L (SD=17.36) vs. 5.9 μg/L (SD=3.48, p=0.016) in samples taken at the mean age of 210 and 314 days, respectively. Indole levels showed similar age- and breed-related variations to skatole. At the time of increased skatole concentrations (age from 180 to 360 days, depending on breed) 25.5% of Yorkshire, 31.6% of Landrace, 20.3% of Hampshire and 61.1% of Duroc entire male pigs had skatole levels above 12.6 μg/L of plasma, which corresponds to the threshold level of 0.20 μg/g of fat that is used for selecting tainted carcasses. The results indicate that increased levels of skatole in entire male pigs are related to puberty and taking skatole measurements at that age could be advantageous when considering genetic selection to reduce boar taint level in entire male pigs. Breed differences should be also taken into account. [Copyright &y& Elsevier]