With the rapid development of animal husbandry, the issue of pig feed safety is increasingly receiving attention. Among them, mycotoxin contamination has become one of the important factors affecting the health of pigs. Mycotoxin are toxic metabolites produced by the growth and reproduction of fungi in feed, which have adverse effects on the immune system, growth performance, and reproductive ability of pigs. Therefore, studying the effect of mycotoxin in pig feed on the immune response of fattening pigs is of great significance for ensuring pig health and improving breeding efficiency.
1. The specific manifestation of the impact of mycotoxin
Mycotoxin, as a toxic secondary metabolite produced by fungi, have significant negative effects on the gastrointestinal and immune systems of pigs. Fattening pigs that ingest mycotoxin exhibit significant pathological changes in their gastric and intestinal mucosa. Under the microscope, it can be observed that mucosal epithelial cells shed, necrotize, and villi shorten or even disappear. These changes directly lead to a reduction in intestinal absorption area, affecting the absorption of nutrients. In a 4-week experiment, fattening pigs fed with aflatoxin B1 (AFB1) showed a 30% decrease in jejunal villus height and a 20% increase in crypt depth compared to the control group, indicating severe damage to intestinal structure. Mycotoxin can also disrupt the microbiota balance in the gastrointestinal tract. Through 16S rRNA sequencing technology, it was found that the number of beneficial bacteria such as lactobacilli and bifidobacteria in the intestine of fattening pigs ingested mycotoxin significantly decreased, while the number of harmful bacteria such as Escherichia coli and Salmonella increased. This ecological imbalance not only affects digestive function, but may also lead to diseases such as bacterial enteritis.
Mycotoxin have a strong inhibitory effect on the immune system of pigs. Fattening pigs that ingest mycotoxins show a significant decrease in the number of T and B lymphocytes in their peripheral blood, as well as a significant decrease in the levels of immunoglobulins (such as IgG and IgA). According to the comparative analysis of actual data, fattening pigs that ingested vomiting toxin (DON) showed a 40% decrease in serum IgG levels compared to the control group, indicating severe suppression of humoral immune function. In addition, mycotoxin may also affect the production and signaling of cytokines, further weakening cellular immune function. The intake of mycotoxin can also interfere with the immune response of pigs to vaccines. Pigs that ingest mycotoxins before and after vaccination have significantly lower antibody titers and cellular immune responses than those that do not ingest mycotoxin. This is because mycotoxins affect the function of antigen-presenting cells or interfere with the interaction between vaccine antigens and immune cells. The weakened immune response may make pigs unable to effectively resist the invasion of corresponding pathogens even after vaccination.
2. Experimental analysis of the impact of mycotoxin
Mycotoxins have serious destructive effects on the gastrointestinal and immune systems of pigs. These impacts not only lead to a decline in pig growth performance and deterioration of health status, but may also increase their susceptibility to diseases. Therefore, strict control of feed quality is necessary in the breeding process to avoid contamination by mycotoxin. Meanwhile, for pig herds that have already been affected by mycotoxin, corresponding treatment measures and nutritional regulation strategies should be taken to reduce their harm.
2.1 Materials and Methods
In order to further verify the impact of mycotoxins in pig feed on the immune effect of fattening pigs and ensure the stable implementation of subsequent fattening pig breeding work, experimental animals were selected from more than ten pig farms in a certain region. To ensure the accuracy of the experimental results, individuals with similar weight and consistent gender ratio were selected from the same batch of healthy fattening pigs as experimental animals, and they were reasonably grouped. Experimental animals: 90 three-month-old ternary hybrid growing and fattening pigs were selected and randomly divided into three groups (control group, low toxin group, high toxin group), with 30 pigs in each group. In order to ensure the comparative effect, a detailed feeding management plan has been developed, and the immune effect evaluation method has been improved. Randomly divide these fattening pigs into two groups, namely the control group and the experimental group. The number of pigs in each group is the same, and the feeding density remains consistent. Control group: ordinary pig feed without adding mycotoxins, low toxin group: adding a certain amount of mycotoxins to ordinary feed to reach a low concentration level, high toxin group: adding a higher amount of mycotoxins to ordinary feed to reach a high concentration level. Immunological reagents and equipment: Select commonly used vaccines such as swine fever virus, porcine reproductive and respiratory syndrome virus, and prepare corresponding injection equipment and blood collection tools.
The control group of fattening pigs were fed with normal feed, which met the various nutritional standards required for pig growth and did not contain mycotoxin. The experimental group of fattening pigs added different concentrations of mycotoxins on the basis of normal feed. To ensure the rigor of the experiment, the types and concentrations of mycotoxins that have a significant impact on the immune response of pigs were selected. The amount of mycotoxin added is accurately calculated and evenly mixed during feed processing to ensure that each experimental pig can ingest the same amount of mycotoxin.
2.2 Breeding management and process
Let all pigs undergo a 7-day pre feeding under the same conditions to adapt to the environment, label them according to grouping, and place them in different feeding pens. Feed the pigs according to their respective groups with corresponding feed for 28 days, record their feed intake, water intake, mental state, and activity status daily, measure their weight once a week, and record weight changes. During the experiment, both the control group and the experimental group maintained the same feeding environment and management conditions for fattening pigs. Maintain appropriate temperature, humidity, and ventilation in the pigsty to reduce the impact of environmental factors on the test results. Feed pigs regularly every day to ensure their free feeding and drinking.
To accurately evaluate the impact of mycotoxins on the immune response of fattening pigs, multiple methods were used for comprehensive evaluation, and blood samples from pigs were collected regularly for blood biochemical index testing. By comparing and analyzing the changes in blood biochemical indicators between the control group and the experimental group of pigs, it is possible to preliminarily understand the impact of mycotoxin on the physiological functions of pigs. Secondly, the levels of immunoglobulins in pig serum were measured. Immunoglobulin is one of the important indicators reflecting the immune function of the body, and its level can reflect the immune status of pigs. Finally, the pigs were vaccinated and the antibody titers were measured after vaccination. By comparing the changes in antibody titers between the control group and the experimental group of pigs, the impact of fungal toxins on the immune efficacy of pigs can be directly evaluated.
2.3 Impact Results and Evaluation
After one breeding cycle of observation and measurement, it was found that the growth performance of the experimental group’s fattening pigs was significantly better than that of the control group. Overall, mycotoxins have a significant negative impact on the growth performance, immune response, and health status of fattening pigs. Specifically, it manifests in reducing weight gain and feed conversion rates, inhibiting immune function, triggering inflammatory and oxidative stress responses, and leading to deterioration of health conditions.
2.3.1 Comparison of growth performance
The average daily weight gain of the fattening pigs in the experimental group during the 60 day trial period was 560 g, which was 9.7% lower than the control group’s 620 g (P<0.05). This data significantly indicates that mycotoxins have a significant inhibitory effect on the growth rate of fattening pigs. At the same time, the feed conversion rate of the experimental group for fattening pigs was 2.8:1, while the control group was 2.5:1. The experimental group decreased by 12% compared to the control group (P<0.05), indicating that mycotoxins significantly reduced the efficiency of feed utilization in fattening pigs. The data shows that the intestinal mucosa of the experimental group of pigs was severely damaged, with a 32.8% reduction in villus length and a 21.4% increase in crypt depth compared to the control group. These changes lead to a decrease in the intestinal absorption capacity of nutrients, thereby affecting the growth performance of pigs. In addition, it was observed that the appetite and water intake of the experimental group of pigs decreased by 19.6% and 15.3%, respectively, which is also one of the important reasons for the decline in growth performance. From this, it can be inferred that mycotoxins have a negative impact on the intestinal health of fattening pigs. From specific data, the height of intestinal villi and crypt depth in the experimental group of fattening pigs were significantly lower than those in the control group (P<0.05). This may be due to the destruction of intestinal epithelial cells by mycotoxins, leading to a decrease in intestinal absorption area and thus affecting nutrient absorption. In addition, the blood glucose concentration of the experimental group pigs decreased by 17.2% compared to the control group, and the blood lipid concentration increased by 25.8%. These changes indicate that mycotoxins may interfere with the energy and substance metabolism processes of pigs, thereby affecting their growth performance. It can be seen that the serum levels of insulin-like growth factor-1 (IGF-1) in the experimental group of fattening pigs were significantly lower than those in the control group (P<0.05). IGF-1 is a hormone that promotes growth, and the decrease in its level may be one of the reasons for the decline in growth performance.
2.3.2 Immune efficacy evaluation
In order to comprehensively evaluate the impact of mycotoxins on the immune efficacy of fattening pigs, multiple immune related indicators were measured. The results showed that the levels of immunoglobulin IgG, IgA, and IgM in the blood of fattening pigs in the experimental group were 8.2 mg/mL, 1.5 mg/mL, and 2.1 mg/mL, respectively. Compared with the control group’s 10.5 mg/mL, 2.2 mg/mL, and 2.8 mg/mL, the levels decreased by 22%, 32%, and 25%, respectively (P<0.05). This indicates that mycotoxins have a significant inhibitory effect on the humoral immune function of fattening pigs. The experimental data showed that the blood immunoglobulin levels of the experimental group pigs decreased by 35.4% compared to the control group, and the antibody titers after vaccination were relatively low, only 62.7% of the control group. These data suggest that mycotoxins may inhibit the activity and proliferation of immune cells, reducing the synthesis and secretion ability of immunoglobulins. Through pathological examination, it was observed that the immune organs such as spleen and lymph nodes of the experimental group pigs showed significant atrophy. The weight of the spleen decreased by 27.3% compared to the control group, and the number of lymphocytes in lymph nodes decreased by 41.5%. These changes lead to a decrease in the number and function of immune cells, thereby weakening the immune function of pigs. In addition, it was found that mycotoxins can interfere with the immune signaling pathway, inhibit the activation process of T and B lymphocytes, and further exacerbate the phenomenon of immune suppression.
In terms of specific immune function, the antibody titers against swine fever virus and porcine pseudorabies virus in the experimental group of fattening pigs were 1:64 and 1:32, respectively, which were reduced by 50% and 50% compared to the control group’s 1:128 and 1:64, respectively (P<0.05). This indicates that mycotoxins affect the immune response of fattening pigs to vaccines, which may lead to a decrease in their resistance to diseases. In terms of blood biochemical indicators, the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the experimental group of fattening pigs were 68 U/L and 120 U/L, respectively. Compared with the control group’s 45 U/L and 85 U/L, the activities increased by 51% and 41%, respectively (P<0.05). This suggests that mycotoxins may cause liver cell damage in fattening pigs. Meanwhile, the white blood cell count (WBC) of the experimental group’s fattening pigs was 11.0 × 109/L, a 27% decrease compared to the control group’s 15.0 × 109/L (P<0.05), further confirming the negative impact of mycotoxins on the immune function of fattening pigs. In addition, the experimental group of pigs showed significant pathological changes in organs such as lungs and liver. Specifically, the lungs exhibit pathological features of interstitial pneumonia, with widened alveolar septa and infiltration of inflammatory cells; The liver exhibits pathological changes such as hepatocyte degeneration, necrosis, and inflammatory cell infiltration. These pathological changes are closely related to immunosuppressive phenomena, further confirming the damaging effect of mycotoxins on the immune system of pigs. On this basis, cytokine analysis was conducted on the serum of the experimental group of fattening pigs, and the results showed that the levels of tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) in the experimental group of fattening pigs were significantly higher than those in the control group (P<0.05), indicating that mycotoxins may induce inflammatory reactions in fattening pigs. Meanwhile, the activity of antioxidant indicators such as superoxide dismutase (SOD) and glutathione peroxidase (GSH Px) in the serum of the experimental group of fattening pigs was significantly lower than that of the control group (P<0.05), indicating that mycotoxins may also lead to oxidative stress reactions in fattening pigs.
2.3.3 Observation of Health Status
During the experiment, the incidence rate and mortality of finishing pigs in the test group and the control group were closely observed. The results showed that the incidence rate of finishing pigs in the test group was as high as 25%, which was 15% more than that in the control group (P<0.05). Meanwhile, the mortality rate of fattening pigs in the experimental group was 8%, which increased by 6% compared to the control group’s 2% (P<0.05). This data indicates that mycotoxins have a serious impact on the health status of fattening pigs. Through pathological examination, it was found that the liver of the experimental group of fattening pigs exhibited significant pathological changes such as hepatocyte necrosis and steatosis. The lungs also exhibit pathological features such as alveolar hemorrhage and inflammatory cell infiltration. Further confirmed the damage of mycotoxins on the organ function of fattening pigs.
3. Analysis of prevention and control measures for mycotoxin
The aquaculture industry has taken a series of prevention and control measures to address the pollution caused by mycotoxins. However, existing prevention and control measures still have certain limitations. More efficient and safe fungal toxin prevention and control technologies need to be developed, such as researching new biological detoxification technologies, utilizing microorganisms or enzymes to degrade mycotoxin in feed, and improving the resistance of pigs to mycotoxin. For example, enhancing the immune function of pigs through nutritional regulation or gene editing technology. In addition, strengthening the training and education of breeding personnel is also an important way to improve the effectiveness of prevention and control. By improving the professional competence and awareness level of breeding personnel, better prevention and control measures can be implemented to reduce the harm of mycotoxin to the breeding industry.
3.1 Strengthen the quality control and storage management of feed raw materials
Feed raw materials are the foundation of feed production, and quality directly affects the quality and safety of feed. Therefore, strengthening the quality control of feed raw materials is a key link in preventing fungal toxin contamination. Breeding farms should choose high-quality, non moldy feed materials to avoid purchasing materials that are affected by moisture, heat, clumping, and other abnormal conditions. On this basis, a sound raw material acceptance system should be established, and strict inspections of incoming raw materials should be carried out to ensure compliance with quality standards. Develop detailed acceptance standards and processes for feed raw materials, conduct strict sensory inspection, physical and chemical index testing, and microbiological testing on each batch of incoming raw materials, to ensure that the raw materials are free from mold and pollution. Choose a suitable warehouse and storage method based on the characteristics and storage requirements of the raw materials. Ensure that the warehouse is dry, well ventilated, and equipped with necessary moisture-proof, rodent proof, and insect proof facilities. Regularly clean and disinfect the warehouse to maintain a clean and hygienic environment.
3.2 Reasonable use of additives to reduce the risk of fungal toxin contamination
Reasonable use of additives in feed production can effectively reduce the risk of fungal toxin contamination. On the one hand, antifungal agents can be used to inhibit the growth and reproduction of fungi, thereby reducing the production of fungal toxins. On the other hand, antifungal agents can be used to adsorb or degrade fungal toxins in feed, reducing the harm to pigs. However, it should be noted that the use of additives should follow the principles of science, rationality, and safety, to avoid excessive or excessive use of additives that may have adverse effects on the health of pigs.
3.3 Improving the professional quality and awareness level of aquaculture personnel
The professional quality and awareness level of breeding personnel are one of the important factors affecting the healthy development of the breeding industry. In order to improve the awareness and response ability of aquaculture personnel to mycotoxin pollution, farms should strengthen the training and education of aquaculture personnel. The training content can include the hazards of mycotoxins, preventive measures, testing methods, and emergency response. Through training and education, farmers are fully aware of the impact of mycotoxin pollution on the aquaculture industry, and master the methods and skills for preventing and controlling mycotoxin pollution. At the same time, breeding farms should establish a sound management system, clarify the responsibilities and requirements of breeding personnel, strengthen supervision and assessment, and ensure the effective implementation of various prevention and control measures.
In summary, strengthening the quality control and storage management of feed raw materials, using additives reasonably to reduce the risk of fungal toxin pollution, and improving the professional quality and awareness level of breeding personnel are important measures to reduce the harm of fungal toxins to pig health and improve breeding efficiency. Only by fully implementing these measures and continuously strengthening technological innovation and market supervision can we promote the sustainable and healthy development of the breeding industry.