Organic pork is a clear alternative to conventional pork because organic pig production, with outdoor access and roughage, is quite different. The low market share (1%) for organic pork provides a promising development potential. Consumer expectation for a natural product means that a stop for castration could provide new marketing possibilities.
A recent pilot study on production of entire males on commercial organic farms indicates that the proportion of organic produced entire male pigs with boar taint is so high that it is a major barrier for a marked orientated growth in organic pig production.
In this project we develop a management concept for future organic pig production without castration, with a documented low level of entire male pigs with a high level of skatol and androstenone in back fat and therefore a minimum risk for boar taint. The risk of boar taint can be reduced by feeding the right feeds in the right combination.
The best feed rations are selected based on their ability to minimize boar taint and tested for consequences for productivity, nutrient utilization and natural disease resistance. Subsequently the best feeding is combined with the best decisions concerning, pig weight when taken from pasture, group size and grouping strategy and slaughter weight and the concept is tested for the overall effect on skatole and androstenone level in male pig.
The consequences for economy and working conditions are demonstrated for farmers and citizens.
2013: Progress and activities:
A high throughput method for simultaneous measurements of skatol and androstenon in fat samples has been established at the Institute of Animal Science, AU. The method can also measure skate and androstenon in fat biopsy samples and skatol and indol in blood samples, but it is not sensitive enough to measure androstenon in blood. More than 6000 samples will be analysed with the method during the project period.
Cultivation experiments has focused on, sweet lupine, chicory root and Jerusalem artichoke. All three crops can be grown with good yield in DK. The chicory root was produced under commercial conditions. Harvesting and drying are expensive and has to be taken in consideration for practical use.
Selected batches of the crops were investigated in experiment with pigs. As well chicory root as Jerusalem artichoke did reduce the skatole level in back fat if the compounds were added to the feed so the concentration of inulin in the feed was about 5%.No effect was found on the androstenone level. No effect of lupine was found neither on skatole or androstenone. Addition of 25% chicory root to the diet had a strong effect on the gastrointestinal ecosystem and was able completely to reduce the establishment of the parasitic worm Oesophagostomum dentatum.
Addition of 15% chicory to the fed the last week prior to slaughter reduce skatole in back fat with approximately 67% and it may be assumed that the sorting out percentage in the same order of magnitude. The number of pigs in the study, however, was too small to be able to give a clear answer to this. This is currently investigated in an experiment carried out with so many pigs that the production economics can be calculated. Similar studies are conducted with feeding grain only the last 3 days before slaughtering and with 15% Jerusalem artichokes 4 days prior to slaughter.
In a study involving 25% chicory root was pigs slaughtered at three different weights (62, 98 and 118 kg live weight). The results showed that the concentration of androstenone in back fat rose markedly with carcass weight (age) of the pigs. Lower slaughter weight (age at slaughter) may very well prove to be the solution to the androstenone problem in organic pig production while the skatol problem can be solved by feed intervention.
Also experiment with assignment of chicory (15%) or lupin (15%) for fattening pigs was implemented by 2 slaughter weights (75 and 95 kg). Also in this experiment it was found that a lower carcass weight reduced Androstenone in back fat (from 1.73 ppm at a slaughter weight at 95 kg to 1.23 at a alaughter weight at 75kg), but did not affect the skatol content in back fat.
In the experiments we have developed a dirtiness assessment scale of the hygiene of individual pig. Fouling of the individually marked pigs, were assessed four times during the production period, and the assessment linked to their risk of boar taint determined by skatole and androstenon content in back fat at slaughter.
Four out of four replicates has been conducted. The results from the first replicate are processed. It was found that 15% of the pigs had a skatol levels about the limit of 0.25 ug / g (mean 0.15 µg / g), and that 71% of the pigs had androstenone levels higher than the proposed limit of 1 µg / g (average value of 2.4 µg / g). There was some variation between the five participating farms, especially in skatol, while the variation was less pronounced for androstenone. Also in this study, a trend toward higher androstenone level by heavier slaughter weight was detected (increasing from 0.96 ppm at a liwe weight at 80 kg to 2.43 ppm at 100kg liwe weight). The upcoming results will show whether the link is safe enough to conclude that the androstenone level can be lowered significantly by reducing the slaughter weight. For skatol, the relationship between pig hygiene and the level of skatol in back fat was analyzed, but preliminary results show no clear relationship.
Together these data indicate that the concept that will be recommended to reduce the amount of organic pigs with boar taint will be a combination of feeding with chicory or exclusively grain the last 4-7 days before slaughter, in combination with the slaughter of the pigs at a low carcass weight (80 to 90 kg live weight).
An agreement is made with organic pig producer Brian Holm to conduct a demonstration project at his farm. This enables that the gathered knowledge from the other activities in the project can be demonstrated overall and that a final concept to production of male pigs raised without castration can be tested and demonstrated under practical production conditions. The final setup of the demonstration experiment is scheduled at a project meeting to be held January 8th 2014.
In cooperation with four other Organic RDD and Core-Organic projects an international workshop as well as a Danish theme day under the theme: The challenges of the future in organic and free range pig production were held on 12 and 13 June 2013. At both events a session was devoted to male pig production, with presentations from NO-CAST partners as well as outside researchers with a focus on boar taints problems. The international workshop was attended by 37 researchers and advisors from 6 countries, while the Danish theme day had participation from 48 organic pig farmers, advisors and researchers.
2012: Progress and activities:
In 2012 cultivation experiments with 3 varieties of root-chicory, sweet lupine and 4 varieties of Jerusalem artichoke have been conducted. The root chicory was harvested at three different times and dried at different temperatures. The chicory root was produced under commercial conditions. Harvesting and drying are expensive and has to be taken in consideration for practical use.
An infection experiment with the parasitic worm Oesophagostomum dentatum has been conducted. The aim of the experiment was to investigate if addition of 25% chicory root to the feed was able to reduce the establishment of the worm, and if the infection with the worm has an effect on the deposition of skatol and androstenon in back fat. Preliminary data from the experiment showed that addition of 25% chicory root to the diet had a strong effect on the gastrointestinal ecosystem and did completely eliminate skatol from gut content and fat samples while no effect was detected on androstenon content I fat samples.
The pigs were slaughtered at three different live weight (62, 98, and 118 kg) there was a strong increase in the androstenon concentration in back fat with increasing live weight (age). Indicating that a reduced slaughter weight may be the way to solve the androstenon problem in organic pig production, while the skatol problem may be solved by adding chicory root to the feed.
Addition of chicory root to the feed did also affect the establishment of the worms in the gut resulting in a lower egg production and as such a lower infection press on the pigs. An experiment was also conducted in which the effect of addition of either 15% chicory root or 15% sweet lupine to the feed was investigated in a production experiment with pigs slaughtered at two slaughter weights ((75 or 95 kg). Again addition of chicory root to the feed resulted in a lower skatol level in back fat, while no effect was found on skatol by the addition of sweet lupine to the feed. Neither, chicory root nor lupine had any effect on the androstenon level in back fat. But also in this experiment the androstenone level in back fat was significantly low in the pigs slaughtered at a slaughter weight at 75 kg compared to the pigs slaughtered at a slaughter weight at 95 kg. No effect of slaughter weight was found on the skatol level I back fat.
Development of the best herd management concept taking into account risks of boar taint, animal welfare and productivity are carried out on five large commercial organic pig herds producing 1800 entire male during a two year period.
Effect of group size and grouping strategy for the welfare of the pigs is investigatedthrough behavioral observations recorded through systematic video recording and clinical observations. In the experiments we have developed a dirtiness assessment scale of the hygiene of the individual pig. Fouling of the individually marked pigs, were assessed four times during the production period, and the assessment linked to their risk of boar taint determined by skatole and androstenon content in back fat at slaughter. Three out of four replicates has been conducted.
The results from the first replicate are processed and the preliminary results show higher levels of skatole and androstenone than expected. It was found that 15% of the pigs had a skatol levels about the limit of 0.25 ug I g (mean 0.15 IJg I g), and that 71% of the pigs had androstenone levels higher than the proposed limit of 1 ~Jg I g (average value of 2.4 IJg I g). There was some variation between the five participating farms, especially in skatol, while the variation was less pronounced for androstenone. Also in this study, a trend toward higher androstenone level by heavier slaughter weight was detected.
The upcoming results will show whether the link is safe enough to conclude that the androstenone level can be lowered significantly by reducing the slaughter weight. For skatol, the relationship between pig hygiene and the level of skatol in back fat was analyzed, but preliminary results show no clear relationship.
An appointment has been made with an organic pig producer to carry out a demonstration experiment at his farm. That will give us the opportunity to investigate under practical conditions the knowledge obtained in the rest of the project and came up with a final concept for organic pig production that eliminate the requirement for castration of male pigs and increase the pig's natural resistance against infection with zoonotic bacteria and parasites.
Bent Borg Jensen
Tel: (+45) 87 15 80 67