Feed interventions and skatole deposition

Skatole produced in the large intestine of the pig and the testicular steroid androstenone are the main substances contributing to boar tainted meat from entire male pigs. Boar taint decreases the quality of the meat and is not accepted by consumers. Until now boar taint has been avoided by castrating male pigs. Surgical castration reduces lean meat percentage, growth rate and feed efficiency, and it causes pain to the animal. This constitutes a problem in relation to productivity and welfare. Different attempts on avoiding surgical castration were either not fully effective, not accepted by the market, or they have a long time horizon for implementation. However, when focusing on the effect of feed interventions on boar taint, previous studies have showed a reducing effect through reduced skatole production in the large intestine after a one week application period. Skatole is produced from the microbial fermentation of L-tryptophan in the large intestine. In the literature it is well documented that skatole production in the large intestine is positively correlated with skatole deposition in adipose tissue. Moreover skatole production can be decreased by adding non-digestible and easy fermentable carbohydrates to the feed. However, little is known about skatole producing bacteria from the large intestine of pigs, and how these bacteria can be affected. This thesis reviews skatole production and metabolism in the pig, and how skatole production can be reduced by affecting the microbial production of skatole in the large intestine. A skatole producing bacterium SK9 K4 was isolated from the gastrointestinal tract of pigs. No such bacterium has previously been described. The bacterium was characterised by 16S RNA sequencing, gram stain, analysis of DNA G-C content, cellular fatty acids composition and DNA hybridisation with closely related bacteria. The fermentation of different carbohydrate sources, the growth pattern, the production of organic acids and the skatole production were studied in vitro. The production of skatole in the large intestine was correlated with skatole deposition in adipose tissue. Skatole production could be reduced when adding a minimum of 20 % raw potato starch or 9 % inulin to the feed. The problem concerning deposition of skatole in adipose tissue seems to be solved through the introduction of feed interventions. However high concentrations of androstenone deposited in adipose tissue remains a challenge. Thus, the feed interventions were not fully effective against boar taint. SK9 K4 was described as cells being strictly anaerobic, occurred singly or in pairs and were gram positive. It was identical with an Olsenella sp. strain isolated from the rumen, an uncultured Olsenella sp. clone isolated from sludge and an uncultured bacterium colon isolated from the oral cavity. Moreover SK9 K4 was closely related to Olsenella uli, Olsenella profusa, Olsenella umbonata and Atopobium parvulum. SK9 K4 and O. uli produced skatole from idole-3-acetic acid but not from L-tryptophan. The major fermentation products were lactic acid together with acetic acid and formic acid. SK9 K4 was not able to ferment raw potato starch, inulin and raw corn starch. Thus, when feeding resistant starch or inulin, the growth of skatole producing bacteria might be reduced followed by a reduced ability to produce skatole. The characterisation of a skatole producing bacterium isolated from the gastrointestinal tract of pigs gives the opportunity to further study the bacterium in vivo. Studies should be conducted to investigate the effect of a control diet compared to a diet added a non-digestible and easy fermentable carbohydrate on the growth of SK9 K4 in the large intestine of the pig

Skatole pattern during the growth period 50 to 100 kg liveweight in entire male pigs of the crossbreed combinations YDxLYD and HxLYD kept in groups of entire male pigs or in groups with dominant female pigs

1. Dominant females do not decrease the skatole and androstenone concentration in entire male pigs being dominated during the growth period from 50-100 kg liveweight (see fig. 1 and 3). 2. The amount of entire male pigs having higher skatole concentrations in blood – corresponding to skatole in backfat > 0.15 µg/g – are surprisingly high at 50 kg and 75 kg liveweight compared to 100 kg (10, 9 and 13 entire male pigs). 3. Furthermore it is not the same pigs having high skatole concentrations during the period from 50 over 75 to 100 kg liveweight. 4. The crossbreed HxLYD had significant higher skatole concentration in backfat at slaughter (100 kg liveweight) compared to the crossbreed YDxLYD (P<0.05)(see fig. 2). However, there was no significant difference in androstenone concentration in backfat at 100 kg liveweight between the 2 crossbreeds (see fig. 3)

Effect of feeding fermentable fibrerich feedstuffs lupin and chicory prior to slaughter with special emphasis on the effect on chemical boar taint in organic entire male and female pigs and technological meat quality

Boar taint is an off-flavour of pork caused primarily by skatole and, androstenone. Pig off-odour and flavour mostly caused by higher skatole concentrations in backfat. It is a problem in all types of pork production and is not restricted to entire male pigs. If uncastrated, 5-10% of Danish entire male pigs (100 kg liveweight) have > 0.25 ppm skatole in backfat and are then classified as boar tainted, having a markedly reduced value. Even backfat skatole values above 0.15 ppm enhance the off-odour for skatole sensitive consumers. An alternative way to reduce high skatole concentrations may be feeding with fibre-rich feedstuffs. This idea is based on previous studies which have demonstrated that 10% dried chicory or more in the feed reduces skatole in entire male pigs significantly after 7, 14 and 21 days of feeding, resulting in a significant reduction in perceived boar taint and thus an improvement in the flavour and taste of meat. Significantly decreased skatole concentrations and a tendency to increased eating quality have also been demonstrated by feeding 25% lupines to female and castrated male pigs during the whole fattening period. The question remains, however, whether the effects of lupines on skatole and other sensory characteristics of female and entire male pigs can be obtained when used only in the last 1 or 2 weeks before slaughter. Two experimental replicates each consisting of 24 pigs (12 entire male and 12 female) was divided into three treatments according to litter and initial weight and kept in pairs (pens) of either female or entire male pigs. The male and female pigs were kept in different stables. The pairs of pigs have been fed three organic diets for either 1 or 2 weeks prior to slaughter of which two diets contained different fermentable fibre-rich feedstuffs (10% dried chicory root plus 90% organic control feed and 25% blue lupine seed plus 75% other organic feed components). These two treatments were compared with a control; where the pairs of pigs were fed organic control concentrate (“conventional”) either 1 or 2 weeks prior to slaughter (at approx. 104 kg liveweight). Levels of skatole and indole in blood plasma from Vena jugularis were monitored at the start of the experiment and just before slaughter, and skatole in backfat was measured at slaughter. Production results were registered (daily weight gain, FUp per kg gain, slaughter weight, carcass meat percentage, warm and cold carcass weight), and after slaughter at Research Centre Foulum the following technological meat quality attributes were measured on M. Longissimus dorsi (LD): meat colour (L*, a*, and b* values), drip loss, pH measurements, temperatures and glycogen at 45 minutes and 24 hours post mortem. There was a significant reduction in skatole in blood and backfat for both sexes by feeding 25% blue lupine one or two weeks prior to slaughter (P<0.001). The 10% (and 13.3%) dried chicory roots showed no significant effect. This is possibly due to error in the heat treatment of the roots during the drying process. A majority of the meat quality parameters were not significantly affected by either of the two dietary treatments. However, glycogen contents tended to be higher 45 minutes and 24 hours post mortem (P<0.10) and the drip loss lower in the lupine-fed pigs. There were clear tendencies to significant differences in production results as the 25% lupines showed negative impact on growth rate, feed conversion ratio, slaughter weight and carcass weight. Newly mixed entire male pigs showed worse performance than newly mixed female pigs during the short time experiment

Economics of boar taint prevention without surgical castration in the pork chain

An economic analyses of boar taint prevention without surgical castration is lacking. This paper explores currently feasible alternatives to surgical castration along the pork chain. The considered alternatives include genetic selection (pig breeding stage); altering management strategies (pig growing stage); slaughter at younger age and lower weight (slaughtering stage). Control measures relevant to these alternatives were designed and examined, using costeffectiveness and cost-benefit analysis. Results show that the option of single-sex raising of entire males is more cost-effective compared to the mixed-sex option. The breeding programs combining selection on boar taint and economics are more cost-effective than programs focusing on boar taint only, and also much more cost-effective than slaughtering at a younger age and lower weigh

Boar taint in very small organic entire male pigs - preliminary results

Very small entire male pigs can be part of a new concept of organic seasonal production of pigs. The concept includes outdoor production of small entire male pigs, very large female pigs and sows slaughtered after first litter. The entire males and the sows are slaughtered in the summer and the female pigs gilts in December. The purpose of the very small entire male pigs is to avoid castration and boar taint at the same time. In order to make the concept special regarding product quality and image, different crossbreeds are considered including a traditional Danish breed. Two seasons (2007 and 2008) are planned. Results of the 2007 season are presented

Chicory roots improves the taste and odour of organic pork

The carbohydrate inulin is known to reduce the production of skatole in pigs. This is caused by inulin changing the intestinal flora, so that the bacteria that produce skatole are held in check. This change in intestinal flora also reduces the number of intestinal parasites in the pigs. However the high cost of inulin makes its use in pig feed impractical. Chicory root contains inulin and a series of other carbohydrates and secondary metabolites. Therefore we have examined whether chicory root can replace pure inulin and thereby reduce boar taint, improve the taste of pork and reduce the infection of pigs with pathogenic parasites and bacteria

Feeding with chicory roots reduces the amount of odorous compounds in colon and rectal contents of pigs

Sixteen pigs (eight entire males and eight females) were given individually two diets, control and control added 25% chopped chicory roots for 2 months before slaughter. Samples were taken from the contents in colon and rectum and subjected to GC-MS analysis for amount of odour impact compounds. The compounds 2-pentanone, ethylbutyrate, propylpropionate, butyric acid, ethyl-2-methylbutyrate, p-cresol, indole and skatole showed a significant difference between the two treatments. The esters, which have relatively pleasant, often fruity odours, increased in the chicory treatment, whereas the malodorous compounds, p-cresol, indole and skatole decreased in the chicory treatment. The measured amounts of compounds were corrected for their odour thresholds as different compounds can have widely different odour thresholds. Principal components analysis was then used to analyse the raw and corrected data results. p-Cresol was the most malodorous compound and together with skatole and indole count as the most malodorous compounds in the colon and rectum cotents. However, butyric acid also had some minor influence. Feeding chicory roots decreased significantly the concentrations of these malodorous compounds, especially if the lowest odour threshold values are used as correction factors

In vivo effect of dried chicory root (Cichorium intybus L.) on xenobiotica metabolising cytochrome P450 enzymes in porcine liver

Cytochrome P450 (CYP) enzymes are widely studied for their involvement in metabolism of drugs and endogenous compounds. In porcine liver, CYP1A2,2Aand 2E1 are important for the metabolism of skatole.Feeding chicory roots to pigs is known to decrease the skatole concentration in plasma and fat. In the present study we investigated the effect of chicory on CYP mRNA and protein expression, as well as their activity. Male pigs were feed dried chicory root for 16 days before liver samples were collected. By the use of RT-PCR and Western blotting we showed that the mRNA and protein expression of CYP1A2 and 2A were increased in chicory fed pigs. The mRNA expression of CYP2E1 was increased, while there was no effect on protein expression. Activity of CYP1A2 and 2A were increased in chicory feed pigs; this was not the case for CYP2E1 activity. In conclusion; oral administration of chicory root for 16 days to pigs increased the mRNA expression of CYP1A2, 2A and 2E1; and the protein expression of CYP1A2 and 2A. The activities of CYP1A2 and 2A were increased

Ebermast – eine Herausforderung für den Ökolandbau

Das Thema Kastration von männlichen Ferkeln wird immer wieder kontrovers zwischen Landwirten, Tierschützern und Politikern diskutiert. Die Kastration mit Betäubung und/oder Schmerzmitteln ist nur teilweise eine Verbesserung. Eine für den Ökolandbau interessante und tierfreundlichere Alternative stellt dagegen die Ebermast dar