Study links dietary DON exposure to subclinical changes in gilts
Bottom line
A new study in Animals examined how dietary deoxynivalenol, or DON, affected immature gilts at two contamination levels: 441 μg/kg and 1,223 μg/kg of feed. The researchers reported no significant differences in average daily gain, feed intake, or feed efficiency between the lower- and higher-DON groups, but they did find signs of physiologic change at the higher exposure level, including lower red blood cell count and hematocrit by day 21, plus shifts in biochemical, immune, reproductive hormone, microbiome, and metabolomic measures. That matters because DON, a Fusarium mycotoxin also known as vomitoxin, is already recognized as a major swine feed risk, and pigs are considered among the most sensitive livestock species. U.S. FDA guidance sets an advisory level of 5 ppm DON in grains and grain by-products for swine, provided those ingredients make up no more than 20% of the diet, while EU guidance for complete pig feed is 0.9 mg/kg. (fda.gov)
Why it matters: For veterinary professionals and swine nutrition teams, the study adds to a growing body of evidence that DON can produce subclinical effects before obvious performance losses show up. That’s especially relevant in replacement gilts, where subtle changes in immunity, gut health, or reproductive signaling may be easier to miss than feed refusal or poor gain. Prior work in pigs has linked low-dose DON exposure with intestinal disruption, altered immune responses, and reproductive effects, reinforcing the need to look beyond growth metrics when evaluating suspect feed. (pmc.ncbi.nlm.nih.gov)
What to watch: Expect more attention on whether low-to-moderate DON exposure in gilt development diets should trigger earlier testing, tighter ingredient screening, or broader use of biomarkers beyond production performance. (asi.k-state.edu)
A newly published Animals study suggests that dietary deoxynivalenol may affect immature gilts in ways that don’t immediately show up on the scale. In the trial, gilts fed diets containing 441 μg/kg or 1,223 μg/kg DON did not differ significantly in average daily gain, feed intake, or feed conversion, but the higher-exposure group showed changes in hematologic, biochemical, immune, reproductive hormone, microbiome, and metabolomic readouts. The findings fit a broader pattern in swine research: DON exposure can be biologically meaningful even when classic production signals remain relatively stable. (mdpi.com)
That context matters because DON remains one of the most common and economically important mycotoxins in swine feeds, particularly in cereal-based ingredients. Pigs are widely regarded as especially sensitive to DON, and the toxin has long been associated with reduced feed intake, vomiting at higher concentrations, immune modulation, and gut injury. Regulatory guidance reflects that concern, though thresholds vary by jurisdiction: the FDA’s advisory level for DON in grains and grain by-products intended for swine is 5 ppm, with those ingredients limited to 20% of the total ration, while the EU guidance value for compound feed for pigs is 0.9 mg/kg at 12% moisture. (fda.gov)
The new gilt study is notable because the reported dietary concentrations sit in a range where overt clinical disease may not be obvious. According to the study abstract, the lower- and higher-DON groups did not separate on headline performance measures, but the lower-DON group had higher red blood cell count and hematocrit than the higher-DON group on day 21. The paper also evaluated gamma-glutamyl transferase, immune indices, reproductive hormones, and intestinal health using microbiome-metabolome approaches, pointing to a more systems-level effect of DON exposure than growth data alone would suggest. That aligns with earlier pig studies showing that low-dose DON can impair gut health, alter intestinal morphology and immune responses, and affect reproductive development or hormone profiles even without dramatic feed refusal. (mdpi.com)
The microbiome-metabolome angle is especially relevant. Previous work has shown that DON and related mycotoxins can alter the pig gut microbiome’s composition and function, and that porcine intestinal microbes can also transform certain DON-related compounds. Other recent research in piglets has tied DON exposure to shifts in metabolites linked to intestinal integrity, inflammation, and microbial activity. Taken together, these studies support the idea that the gut may be both a target of DON toxicity and part of the animal’s biologic response to exposure. (mdpi.com)
Industry and academic guidance has increasingly warned against relying only on growth performance when assessing DON risk. Kansas State’s swine nutrition guidance notes that grow-finish pigs may show no obvious signs below 1 ppm, while higher levels are associated with sharp feed intake drops and reduced growth. But newer research suggests that “no obvious signs” does not necessarily mean “no biologic effect,” particularly in younger or developing animals. A 2025 MDPI study in weaned female piglets found that even the lowest tested DON dose altered reproductive hormone profiles and other health markers without necessarily causing dramatic performance changes, reinforcing concern about subclinical exposure in replacement females. (asi.k-state.edu)
Why it matters: For veterinarians serving swine systems, this study is a reminder that feed-related risk assessment in gilts shouldn’t stop at average daily gain and feed disappearance. Replacement females are a high-value population, and subtle disruptions in immune status, intestinal function, or reproductive signaling can have downstream consequences that are harder to detect in real time. In practice, that means herd investigations involving inconsistent thrift, vague inflammatory signals, or reproductive underperformance may warrant a closer look at mycotoxin exposure, even when diets fall near or below commonly referenced action thresholds. (pubmed.ncbi.nlm.nih.gov)
It also underscores the value of feed testing and ingredient-level scrutiny. DON contamination is often unevenly distributed in grain lots, and co-contamination with other Fusarium toxins can complicate interpretation. Veterinarians, nutritionists, and production teams may need to pair ration review with lab analysis, source tracing, and, where appropriate, mitigation strategies such as ingredient substitution or validated detoxification approaches. Evidence from nursery pig work suggests some interventions can improve performance under higher DON challenge, but responses depend on dose, age, diet composition, and the specific mitigation tool used. (krex.k-state.edu)
What to watch: The next question is whether these microbiome, metabolome, immune, and hormone changes translate into measurable reproductive or lifetime productivity effects in replacement gilts, and whether future studies can identify practical biomarkers that veterinarians can use before performance problems become obvious. (mdpi.com)
Common questions
Did the study find growth problems in immature gilts fed DON?
No. The lower- and higher-DON groups did not differ significantly in average daily gain, feed intake, or feed conversion.What changes did the higher-DON group show?
The higher-exposure group showed lower red blood cell count and hematocrit by day 21, along with changes in biochemical, immune, reproductive hormone, microbiome, and metabolomic measures.What DON levels were tested in the gilts?
The diets contained 441 μg/kg and 1,223 μg/kg of DON.Why does this matter for replacement gilts?
The study suggests DON can cause subclinical effects before obvious performance losses appear, which may affect immunity, gut health, and reproductive signaling in replacement gilts.