Physiological aspects of androstenone and skatole formation in the boar—A review with experimental data

Boar taint is a major meat-quality defect in pigs and is due to excessive accumulation of skatole and androstenone in adipose tissue. The present work investigated the relationship between carcass weight, levels of skatole and androstenone in adipose tissue, and expression of the hepatic androstenone-metabolising enzyme 3b-hydroxysteroid dehydrogenase (3b-HSD), in 22 entire male and 22 entire female crossbred pigs (Large White (40%) 3 Landrace (40%) 3 Duroc (20%)). Animals of each gender were divided into two subgroups (11 pigs in each subgroup): (i) conventional weight (carcass weight 59 to 77 kg) and (ii) heavy weight (carcass weight 84 to 95 kg). No relationship between carcass weight and adipose tissue skatole level was found for entire male pigs (r 2 5 0.013, P > 0.05). There was a significant negative relationship between carcass weight and expression of the hepatic 3b-HSD protein (r 2 5 0.502, P , 0.001) and a significant negative relationship between 3b-HSD protein expression and androstenone level in adipose tissue (r 2 5 0.24, P , 0.05) in entire males. No relationship was found between carcass weight and 3b-HSD protein expression in female pigs (r 2 5 0.001, P > 0.05). 3b-HSD expression was 59% higher in conventional-weight male pigs when compared with heavy-weight animals (P , 0.05) and 36% higher in heavy-weight females when compared with heavy-weight males (P , 0.05). It is concluded that an increase in slaughter weight of entire commercial crossbred Large White pigs is accompanied by inhibition of expression of the hepatic 3b-HSD protein, which might result in a reduced rate of hepatic androstenone clearance with its subsequent accumulation in adipose tissue. It is suggested that regulation of pig hepatic 3b-HSD expression is under the control of sex hormones.

Section: Discussionsupporting

confidence: 54%

Relationship between carcass weight, adipose tissue androstenone level and expression of the hepatic 3β-hydroxysteroid dehydrogenase in entire commercial pigs

Nicolau-Solano

Whittington

Wood

et al. 2007

“…Androstenone is synthesized in the testes of sexually mature boars and released into the blood, while skatole is formed by intestinal bacteria from L-tryptophan and absorbed into the blood (Claus et al, 1994). Both substances accumulate in the adipose tissue.…”

Section: Introductionmentioning

confidence: 99%

Performances, meat quality and boar taint of castrates and entire male pigs fed a standard and a raw potato starch-enriched diet

Pauly

Spring

O’Doherty

et al. 2008

In Europe there is increasing concern about the common practice of surgical castration of piglets without anaesthesia. One possible alternative to completely avoid castration is entire male pig production. Thus, the objective of the study was to compare the growth performance, carcass characteristics, organ weights, meat quality traits, fat score and boar taint compounds in the adipose tissue of group-penned entire male pigs and castrates. Furthermore, the effect of raw potato starch (RPS) fed for 7 days prior to slaughter was determined. Pigs (n= 36) were blocked by BW into 12 blocks (3 littermates/block) and assigned to three experimental groups: surgical castrates (C); entire males (EM); and entire males offered RPS (30 g RPS/100 g diet) for 7 days prior to slaughter (EM+). Pigs hadad libitumaccess to the feed from 22 to 107 kg, individual feed intake was recorded daily and BW once a week. Entire males grew slower (EM: 771, EM+: 776v. C: 830 g/day;P< 0.01), consumed less feed (EM: 1.87, EM+: 1.89v. C: 2.23 kg/day;P< 0.01) and were more efficient (feed conversion ratio: EM: 2.42, EM+: 2.44v. C: 2.69 kg/kg;P< 0.01) than C. Compared to C, carcass dressing percentage was lower (EM: 79.4, EM+: 79.4v. C: 81.6%;P< 0.01) and percentage of valuable cuts was higher (EM: 57.3, EM+: 56.5v. 52.6%;P< 0.01) in entire males. The hearts (EM: 426, EM+: 425v. C: 378 g), kidneys (EM: 387, EM+: 378v. C: 311 g), bulbourethral (EM: 200, EM+: 195v. C: 7 g) and salivary glands (EM: 99, EM+: 94v. C: 42 g) were heavier (P< 0.001) in entire males than in C. Meat quality traits did not (P> 0.05) differ among experimental groups but the adipose tissue was more unsaturated in entire males than in C as indicated by the higher fat scores (EM: 69.1, EM+: 67.2v. C: 63.6;P< 0.01). Feeding RPS reduced (P= 0.04) the skatole tissue concentrations (expressed in μg/g lipid) in EM+ (0.22) compared to EM (0.85), whereas androstenone and indole levels were not (P⩾ 0.60) affected (EM: 1.7 and 0.10, EM+: 2.0 and 0.09, respectively). Although the current results confirmed the high efficiency of entire males compared to castrates, the observed high androstenone levels represent a major challenge to implement entire males production.

“…No obvious differences between herds regarding feed composition, production system or breeds were present between herds explaining such variation. However, variation in stage of puberty between animals as well as health status could be causable factors (Claus et al, 1994;Skrlep et al, 2012). Moreover, preslaughter conditions inducing stress is suggested to affect both skatole and androstenone concentrations (Wesoly et al, 2015), and even this is not accounted for in the present study, such conditions could vary between herds.…”

Section: Discussionmentioning

confidence: 65%

Effect of faecal soiling on skatole and androstenone occurrence in organic entire male pigs

Thomsen

Edwards

Jensen

et al. 2015

Production of entire male pigs could be a future strategy for organic pig production. However, production of entire males leads to increased risk of carcasses with elevated boar taint levels. It is hypothesized that skatole levels in pig meat are affected by faecal soiling and that organic housing facilities can increase the risk of pigs being heavily soiled. Therefore, the overall aim of this study was to investigate if increased pig and pen soiling increases skatole concentration in entire male pigs. In five herds, 1174 organic entire male pigs were reared in four batches across two seasons, summer and winter. Measurements of pig and pen soiling, as well as fat skatole and androstenone concentration and human nose sensory tests of fat odour, were performed. Skatole and androstenone concentrations varied greatly within and between herds with a 10% and 90% percentile for the overall population of 0.02 and 2.25 µg/g for skatole and 0.53 and 4.84 µg/g for androstenone. Human nose positive tests averaged 18.3% with great variation between herds and seasons. Pen soiling had significant effects on pig soiling. Moreover, outdoor pen soiling significantly affected skatole concentration in interactions with herd and season ( P < 0.001 and P = 0.003) and affected human nose positive risk in interaction with herd ( P = 0.005). Soiling on indoor pen areas did not affect skatole levels and no effect on androstenone was found for any pen area. Soiling of pigs affected both skatole and androstenone levels, with the size of the head and abdomen body areas covered in manure showing significant positive effects on skatole concentration. No effect of density of the manure layer was found on either boar taint measure. Herd significantly affected both skatole and androstenone in fat as well as the human nose positive risk. The human nose test revealed no effect from pig soiling. A large variation in the different boar taint measures was found for both high and low scores of pen and pig soiling, and only a small difference in skatole and androstenone concentrations between the high and low soiling categories was found. Therefore, while increasing the hygiene management could be a strategy for reducing boar taint in production of organic entire male pigs, it should be emphasized that other factors would also need to be considered.