Activated diatomaceous clay tackles toxic effects of zearalenone in piglets

Sunday, June 7, 2015

Zearalenone is the primary toxin causing infertility, abortion or other breeding problems in pigs. Now research in Spain suggests that adding ADC can offset the toxicity without affecting performance

by JANICE MURPHY

Zearalenone is a non-steroidal estrogenic mycotoxin produced by some Fusarium and Gibberella species. It is heat-stable and can be found worldwide in cereal crops, such as corn, barley, oats, wheat, rice and sorghum. Once metabolized, zearalenone turns into zearalenol in the liver and intestinal mucosa, causing estrogenic and anabolic effects in the reproductive tract.

Zearalenone is the primary toxin causing infertility, abortion or other breeding problems in pigs. The main symptoms described in swine exposed to zearalenone are anestrous and reduced litter size in sows, edema of the vagina, mammary gland enlargement, and swelling and reddening of the vulva in gilts.

Although it is common when dealing with mycotoxins to think that the "solution to pollution is dilution," there are other approaches to consider. Many nutritionists advocate feed additives that provide a practical way to bind or metabolize mycotoxins in the gastrointestinal tract, thereby eliminating their toxic properties. Several products – activated charcoal, bentonite, hydrated sodium calcium – have been tested on Fusarium toxins against zearalenone in the gastrointestinal tract of different species. Unfortunately, many of these products have not provided convincing results during in vivo experiments.

Activated diatomaceous clay is an additive designed to bind zearalenone when included at a low dosage rate in feed. This clay has been derived from the modification and activation of a diatomaceous soil, a natural material extracted from a quarry containing a maximum of 70 per cent silicon dioxide. This particular clay features a highly porous surface and boasts an average adsorption on a zearalenone solution (1.5 μg/mL) of 44 per cent at 0.1 per cent inclusion, 73.5 per cent at 0.2 per cent inclusion, and more than 95 per cent at 0.5 per cent inclusion of activated diatomaceous clay.

Two experiments were recently conducted at the Universitat Autònoma de Barcelona in Spain to evaluate the efficacy of activated diatomaceous clay in reducing the toxic effects of zearalenone in piglet diets. The researchers hypothesized that the supplementation of activated diatomaceous clay at one, two and five grams per kilogram in contaminated diets would reduce the toxic effects associated with zearalenone on organ weights, reproductive traits, zearalenone residues, and serum biochemistry of weaned pigs.

Sixty-four female piglets (initial bodyweight of 14.9 kilograms) were fed one of eight experimental diets for 26 days with the following treatments: zero or 0.8 mg zearalenone (ZEA) per kilogram of feed; zero, one, two or five grams of activated diatomaceous clay (ADC) per kilogram of feed.

Growth performance and feed intake were monitored in order to determine average daily feed intake, average daily gain and feed efficiency at the end of the experiment. Serum samples were collected to assess for biochemical markers of liver damage and piglets were euthanized at the end of the experiment to determine visceral organ weights.

Dietary treatments did not affect piglet performance (which averaged 1.26 kilograms per day average daily feed intake, 0.69 kilograms per day average daily gain, and 0.55 gain:feed ratio) or the relative weights of the liver, spleen during the experiment. However, piglets fed the ZEA-contaminated diet had significantly heavier relative weight of the uterus and ovaries compared with gilts fed the control diet.

The addition of five grams ADC per kilogram of feed to the ZEA-contaminated diets significantly offset the toxic effects of zearalenone in the relative weight of the uterus to values not significantly different to those of the control diet. Adding activated diatomaceous clay to uncontaminated diets had no effect on the weight of the uterus (see Table 1).

Dietary treatments had no effect on serum protein, and bilirubin concentrations and the activities of glutamate dehydrogenase (GLDH) (see Table 2). Consumption of a 0.8 milligram ZEA per kilogram contaminated diet did increase serum alkaline phosphatase (ALP) activity. However, adding ADC to the ZEA-contaminated diets at levels of two and five grams per kilogram of feed restored its level to values not significantly different from those of the control group. Zearalenone (10.5 µg/kg) and zearalenol (5.6 µg/kg) residues were detected in the bile of piglets fed the zearalenone treatment, but not in those piglets fed the control or ADC diets. Supplementation of ADC to the ZEA-contaminated diet significantly reduced the ZEA content in bile to 2.3 μg/kg.

The experimental results show that performance was not affected by ZEA-contaminated diets in piglets at a lower concentration (0.8 milligrams ZEA per kilogram of feed). The most notable effect of zearalenone was the increase of uterus (54.1 per cent) and ovary weights (34.4 per cent) in piglets. These results concur with previous studies and confirm the potential estrogenic effect of zearalenone on the reproductive system of female piglets.

The piglets fed diets containing activated diatomaceous clay showed no negative impacts on the variables that were measured and confirm a potential protective role against the toxicity of zearalenone. The main effects of zearalenone in the diet were the increase on the weight of the uterus and ovaries, but activated diatomaceous clay was able to reduce these toxic effects. Dietary inclusion of clay at five or 10 grams per kilogram of feed in the diet was effective in preventing the detrimental effects of zearalenone in postweaning female piglets.

The experimental results also showed a significant interaction between ZEA and ADC supplementation in the serum concentration of ALP and in the presence of ZEA residues in the bile of piglets fed ZEA-contaminated diets. The zearalenone and zearalenol residues were detected in bile fluids, but not in liver tissues of piglets, suggesting that the concentration of zearalenone and its derivatives in bile may be considered a specific indicator of intestinal absorption and exposure to zearalenone. Supplementation of ADC to the ZEA-contaminated diet significantly reduced zearalenone concentration in bile fluid.

According to the literature, this is the first time a study has confirmed the ability of an adsorbent to reduce the concentration of zearalenone metabolites in the bile of pigs. The researchers indicated these results proved that ADC has the ability to bind zearalenone and reduce its bioavailability in the gastrointestinal tract as a safe way to prevent the toxic effect of this mycotoxin.

The data from this experiment confirm that long-term consumption of zearalenone causes changes in the reproductive tract in piglets and results in zearalenone residue in the bile of piglets. In this experiment, providing at least two or five grams per kilogram of ADC to the ZEA-contaminated diets overcame the negative effects of dietary zearalenone and accelerated the recovery from toxicity in pigs during and after a zearalenone challenge. BP

Source: M. Denli, J. C. Blandon, M. E. Guynot, S. Salado, and J. F. Pérez. 2015. Efficacy of activated diatomaceous clay in reducing the toxicity of zearalenone in rats and piglets. J. Anim. Sci. 2015.93:637–645

Janice Murphy is a former Ontario agriculture ministry swine nutritionist, who now lives and works in Prince Edward Island.