Deoxynivalenol in pigs
Introduction and a general approach
Nowadays, food and feed safety is an issue of major importance all around the world. This has led to an increasing interest in controlling contaminants in feed, such as fungal toxins (mycotoxins) and on elucidating the direct implications of this contamination on human and animal health.
Deoxinivalenol is one of the most relevant mycotoxins, since it can cause serious health problems, apart from important economic losses in pig farming.
Due to these reasons, general aspects of this mycotoxicosis will be discussed in this article.
DEOXINIVALENOL: GENERAL ASPECTS
- ¿What is deoxinivalenol?
Deoxinivalenol (DON), also known as vomitoxin, is one of the mycotoxins belonging to the trichothecenes family, and it is produced by fungi from the Fusarium genre, mainly by the species F. graminearum and F. culmorum. Its chemical structure has a sesquiterpene group, giving DON a tissue-necrotising activity.
Image 1. DON’s molecular structure.
- Pigs’ sensitivity to DON
Unlike birds, which are very tolerant to DON, pigs are one of the most sensitive species to this mycotoxin. This greater sensitivity could be due to:
- A fast DON absorption in the porcine intestine
- Absorption takes place, mainly, in the proximal portion of the small intestine
- There is little biotransformation of DON to DOM-1 (non-toxic form) by the microorganisms in the pig’s intestine
Image 2. DOM-1, DON’s metabolite, which is much less toxic.
- DON’s effects
The capacity of DON to alter the intestinal morphology is very well known. It specifically affects tight junctions between enterocytes, causing the intestinal wall’s disruption, a reduction of nutrients absorption and an increase in mucosa’s permeability.
- Signs in pigs
The necrotising effect affects the digestive tissues mainly, so the lesions in animals are usually located in the snout, oesophagus, stomach, intestine with variable intensity depending on the mycotoxin’s concentration ingested and the contacting time. Consequently, a decrease in feed intake, digestibility, stunted growth and even vomiting may be observed.
These changes negatively affect other productive parameters, for example, reproduction.
Diagram 1. DON’s main effects on the organism and their relations. Source: adapted from U. Tiemann & S. Dänicke, 2016.
Image 3. Pig’s stomach affected by trichothecenes. Source: Pathology Blog, Veterinaria Digital www.veterinariadigital.com
The control of the presence of DON in feed is essential, since this mycotoxin disrupts the basic intestinal functions and decreases resistance against enteric pathogens, acting as a predisposing factor of suffering other digestive diseases. Moreover, the ingestion of pork meat is a risk element for human health.
The methods to set up an effective control will be discussed in the following article.
There is a broad variety of methods that have been proposed to palliate deoxinivalenol (DON)’s effects. These strategies can be classified into two major groups:
- Technical treatments: feed is whether chemically, physically or biologically manipulated before being administered to the animals.
Although there are treatments among this class that may be able to solve miyotoxins’ problem, none of them is handy and/or affordable on a large scale.
- In situ treatments: adsorbents, probiotics or enzymes that are used to reduce DON’s effects during the digestion.
One of the most used in situ treatments, which has been proved to be the most effective on controlling mycotoxicosis, is the use of mycotoxin binders, which reduces toxins absorption and, therefore, avoids their negative effects on livestock and the existence of contaminated animal products in the food chain.
Clays are one kind of binder that can be found in the market. Multiple studies have documented an improve on weight gain and feed conversion ratio in pigs fed diets supplemented with binders, thanks to the reduction of the toxic effects caused by the intake of mycotoxins.
Despite the similarities that a clay may have to another, their efficacy can greatly vary, since it depends on three major factors that modify the binder’s adsorption capacity: the structure of their particles, their surface properties and their ions.
Treatments can be applied to these materials in order to optimize their adsorption surface, and so their ability to bind mycotoxins. These products (with an increased adsorption capacity) should be taken into account when fighting against mycotoxicosis, since the amount of clay that can be added in feed is limited so it is much better if the maximum number of mycotoxins get attached to the smallest dose of clay. This way, at a lower dose, the product can bind a larger amount of molecules. In pigs, clay’s efficacy is especially important because small amounts of DON that don’t get attach to the binder can negatively affect their productive parameters.
Nowadays, there is a binder with a great capacity of adsorbing mycotoxins called Silicoglycidol, a patented silicate molecule that has undergone a specific process to achieve an optimized surface that permits binding a broad spectrum of mycotoxins with the maximum affinity. This binder can fix a high percentage of the mycotoxins present in feed when included in small amounts.
FIELD TRIAL: SILICOGLYCIDOL vs. DON
The aim is to determine Silicoglycidol’s binding efficacy in feed contaminated with DON by using the productive parameters as indicators of its binding efficacy.
The essay involved 45 piglets with an initial weight of 15 kg (approximately), which were divided into 3 batches of 15 piglets each.
- Batch 1: Pigs fed a non-contaminated corn-based diet (negative control)
- Batch 2: Pigs fed a contaminated corn-based diet with 5 ppm of DON.
- Batch 3: Pigs fed a contaminated corn-based diet with 5 ppm of DON and Silicoglycidol (binder) at 0.5 kg/Tm.
Batch 3 (feed contaminated with DON + Silicoglycidol) achieves:
- A better average daily weight gain and, therefore, a better weight gain than batch 2 during all the phases.
- A better feed conversion ratio than the other two batches in phases II and III.
- 3.6% better than batch 1 (non-contaminated feed)
- 7.10% better than batch 2 (feed contaminated with DON)
This essay verifies the efficacy of this synthetic silicate mycotoxin binder (Silicoglycidol) to counteract the negative effects of DON on pigs’ growth. What’s more, this product is capable of improving the productive parameters of the control group, which is fed non-contaminated food.
Silicoglycidol molecule is available in the product Alquerfeed Antitox (Biovet S.A.)
MV. Júlia Pié Orpí
Veterinary Technical support to the area of Latin America at Biovet S.A. Laboratories Official Veterinary Services (SVO) in poultry slaughterhouse