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Introduction
The swine production industry has a growing interest in the use of essential oils (EO); however, we often lack the necessary information for their use. The aim of this publication is to try to clarify some concepts on their use in swine production.
Essential oils are chemical compounds that are normally found in plants and which are basically of the following types:
- Phenolicos (thymol, carvacrol and eugenol)They can be extracted with organic solvents, distillation or they can be chemically synthesized. They must be protected when transported since they are highly volatile, thermosensitive, photosensitive and easily oxidized.
- Terpenoids (citric and pinapple extracts)
- Alkaloids (capsaicine)
- Lectins
- Aldehydes and ketones (cinamic aldehyde)
- Polypeptides
- Polyacetylenes
Actions
Vegetable extracts have the following properties:
1. Antimicrobials in vitro and in vivo.We can compare the antimicrobial activity of some of the EO used most in alimentation against different bacteria, using the action of thymol (1,0) as a base. As we can see in the following table the EO have different activities against different microorganisms.
2. Antioxidants.
3. They increase consumption and digestion.
4. Immunostimulants
| Extract | E. coli |
Salmonella |
Campilobacter |
Listeria |
| Carvacrol | 1,0 | 0,6 | 2,0 | 1,0 |
| Thymol | 1.0 | 1,0 | 1,0 | 1,0 |
| Eugenol | 0,5 | 0,3 | 1,0 | 1,3 |
| Cinamic aldehyde | 1,0 | 0,8 | 6,7 | 4,0 |
| Oregano | 1,2 | 0,6 | 1,0 | 1,0 |
We can also compare the average antimicrobial activity of some EO used most against different types of bacteria, taking thymol as a reference (1,0). As we can see in the following table the general activity is different between the distinct EO.
| Extract | Action |
| Thymol | 1,0 |
| Carvacrol | 1,0 |
| Cinamic Aldehyde | 4,1 |
| Eugenol | 0,8 |
| Average | 0,5 |
We could extend the number of EO and we would see similar results. However, the referenced EO are those that are most used currently.
Mode of action
The antimicrobial mode of action of the EO is by permeabilization of the microbial membrane. This effect has been shown by turbidometry on putting the EO in contact with the bacteria, indicating that there is a loss of cellular content. This effect is synergic to that of the acidifiers.
Applicactions
EO are used in the food industry as condiments and preservatives, and in human pharmocology (dermatology, oral and nasal hygiene, cosmetics, topically used antiseptics). There are even published clinical tests in which EO are used as a palliative therapy for the HIV virus.
In the animal production industry, EO are used most in aviculture and there are bibliographic revisions that are quite complete. In ruminants, EO are used to control ruminal flora.
In swine production, the published scientific works are focused on the following areas of use:
1. Antimicrobial for piglets or for growers-finishers.In the scientific literature there is an enormous variability of results from in vivo tests, some excellent and others very poor. In vitro, the effects are very clear and determining, while in vivo the situation is distinct. This variability is due to:
2. Substitutes for growth promoters.
3. Appetite stimulants for sows.
4. Antioxidant and preservative in the meat industry.
5. Prevention of bad smells in manure.
1. Different types of products and mixes used in the testsIn any case, the number of publications is increasing exponentially, and the most frequent areas of study in swine production are in the use as antimicrobials, as stimulants of appetite and digestion, and as antioxidants for the meat industry.
2. Different types of sanitary/immunitary situations
3. Deficiency in the installations, models or experience in the tests with immunostimulated pigs.
4. Little standardization of conditions.
Recommendations
Our recommendations are:
1. EO are important products and they should be valued in your country.
2. As a product there is still a certain market immaturity
3. Variable results, but certainly interesting in some cases.
4. Test in suitable conditions.
Conclusions
EO are products of complex origin. They have antimicrobial and antioxidant effects, they stimulate appetite and intestinal secretions and they are even immunostimulants.
They are volatile, photosensitive, thermosensitive and they can be easily oxidized. For these reasons it is highly recommendable to use products that are very well protected and transported.
The in vivo results are somewhat more variable than those obtained in vitro basically due to the variability of the products and conditions used in the tests. Currently, more research is ongoing in their effect associated to other compounds such as acids, prebiotics and probiotics.
In the coming years we will see more and more research and use of these components.
