**3. Aflatoxins occurrence in feeds**

pounds can enter the food chain, mainly, by ingestion through the diet of humans and ani‐

There is strong evidence that the carcinogenicity of aflatoxins operates by a genotoxic mech‐ anism of action that involves metabolic activation to a genotoxic epoxide metabolite, forma‐ tion of DNA adducts, and modification of the TP53 gene. In humans, hepatocellular carcinomas from areas of high exposure to aflatoxins, up to 50% of tumors have been shown to harbor a specific point mutation in the TP53 tumor suppressor gene [9]. Table 2 shows aflatoxin main producing species and toxic effects, pointed by the International Agency for

AFB1 is the most potent carcinogenic substance naturally produced by *Aspergillus* species. Indeed, AFB1 is classified by IARC as Group 1 carcinogen [10]. This compound is certainly acutely toxic to humans, is probably responsible for liver necrosis following chronic expo‐ sure, and may be involved in the epidemiology of human liver cancer in some parts of the world perhaps synergistically with hepatitis B virus (Van Egmond, 1989a cited by [4]).

After ingestion, aflatoxin B is metabolized by enzymes to generate a reactive 8,9-epoxide metabolite that can be bound to DNA as well as to serum albumin forming aflatoxin-N-7 guanine and lysine adducts, respectively. Covalent binding to DNA is considered to be a

Determination of these metabolites was solved by developing enzyme linked immunosorb‐ ent assay (ELISA) methods (Vidyasagar et al., 1997 and Nayak, et al., 2001 cited by [11]). The biosynthesis of aflatoxins is induced by sugars. The induction is associated with the tran‐ scriptional activation of the pathway genes and the pathway regulatory gene, aflR. The reg‐ ulation of aflatoxin biosynthesis had been examined by manipulating the transcription of aflR. Studies concerning this topic showed that constitutive overexpression of the pathway transcriptional regulatory gene aflR led to higher transcript accumulation of pathway genes

and increased aflatoxin production (Flaherty and Payne, 1997 cited by [11]).

1162-65-8 Hepatotoxic, genotoxic, carcinogenic,

7220-81-7 Limited evidence for carcinogenicity

1165-39-5 Sufficient evidence of carcinogenicity

7241-98-7 Inadequate evidence for carcinogenicity

immunomodulation

*Aflatoxins Main producing species CAS No. Toxic effect*

*A. flavus, A. parasiticus, A. nomius, A. bombycis*

*A. flavus, A. parasiticus, A. nomius, A. bombycis*

> *A. parasiticus, A. nomius, A. bombycis*

> *A. parasiticus, A. nomius, A. bombycis*

**Table 2.** Main producing species and effects of aflatoxins [6,10].

critical step in aflatoxin hepatocarcinogenesis [11].

mals (Miraglia et al., 1996 cited by [11]).

174 Aflatoxins - Recent Advances and Future Prospects

Research on Cancer (IARC).

B1

B2

G1

G2

Time of harvest has been shown to be important in influencing the occurrence and levels of aflatoxin because *Aspergillus* does not compete well with other molds when corn presents more than 20% moisture. Harvesting corn when moisture content is above 20% followed by rapid drying to at least 14% moisture content within 24 to 48 hours of harvest can inhibit *Aspergillus* growth and toxin production. Contaminated grains and their byproducts are the most common sources of aflatoxin. Corn silage may also be a source of aflatoxins, because the ensiling process does not destroy toxins already present in silage [12].

On the farm, more than one mold or toxin may be present in the contaminated feed, which of‐ ten makes definitive diagnosis of aflatoxicosis difficult. The prognosis of aflatoxicosis depends upon the severity of liver damage. Once overt symptoms are noticed the prognosis is poor. Treatment should be directed at the severely affected animals in the herd and further poison‐ ing prevented. Aflatoxicosis is typically a herd rather than an individual cow problem. If afla‐ toxicosis is suspected, feed should be analyzed immediately. If aflatoxins are present, the source should be eliminated immediately. Levels of protein in feed and vitamins A, D, E, K and B should be increased as the toxin binds vitamins and affects protein synthesis. Good manage‐ ment practices to alleviate stress are essential to reduce the risk of secondary infections which must receive immediate attention and treatment [12].

Importantly, it has been demonstrated that simple measures can significantly reduce the risk of mycotoxin exposure on farm. Storage of grain at appropriate moisture content (below 130 g kg-1), inspection of grain regularly for temperature, insects and wet spots will limit the possibil‐ ity of fungal development in feeds and feedstuffs as discussed before. The risk of feed contami‐ nation will be reduced in animal units with rapid turnover of feed because there will be less time for fungal growth and toxin production [17]. Aflatoxin is just one of many mycotoxins that can adversely affect animal health and productivity. Care regarding animal feed must be extended not only to the nutritional and economic value, but also to food quality [13].

ia and even mortality may happen. Not only swine is affected by aflatoxins but all species, being the main clinical signs and lesions reported as decreased weight gain, digestive disor‐

Aflatoxins Importance on Animal Nutrition http://dx.doi.org/10.5772/51952 177

A total of 480 poultry feed samples from Rio de Janeiro state were collected monthly during one year and analyzed, being the main fungal species found *P. citrinum* (35% of the samples) followed by *A. flavus* (25%) which is the main aflatoxin producer microorganism. AFB1 lev‐ els ranged from 1.2 to 17.5 ppb. There were no significant differences (P<0.001) between all months tested except February and March when the highest and lowest AFB1 production was found [23]. In Pakistan, a total of 216 samples of poultry feed ingredients were assayed, being found maximum 191.65 ppb for AFB1, 86.85 ppb for AFB2, 89.80 ppb for AFG2 and 167.82 ppb for AFG1. Minimum aflatoxins were produced in the winter season. The temper‐

Recently [25], a survey reported the association of mycotoxins with hematological and bio‐ chemical profiles in broilers. The authors performed meta-analysis using data from 98 arti‐ cles, totaling 37,371 broilers. Some conclusions of this review were that mycotoxins reduced (P<0.05) the hematocrit (−5%), hemoglobin (−15%), leukocytes (−25%), heterophils (−2%), lymphocytes (−2%), uric acid (−31%), creatine kinase (−27%), creatinine (−23%), triglycerides (−39%), albumin (−17%), globulin (−1%), total cholesterol (−14%), calcium (−5%), and inor‐ ganic phosphorus (−12%). Mycotoxins also altered (P<0.05) the concentrations of alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase. The total protein concentration in blood was 18% lower (P< 0.05) in broilers challenged by aflatoxins com‐ pared with that of the unchallenged ones. The inclusion of antimycotoxin additives in diets with aflatoxins altered (P<0.05) some variables (uric acid, creatinine, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, and γ-glutamyl transferase) in rela‐

ature varies from 10 to 45 ºC in this country, favorable to *Aspergillus* growth [24].

tion to the group that received diets with the mycotoxin and without the additive.

the world's animal feedstuffs are significantly contaminated by mycotoxins.

over three fold when 20 ppm aflatoxin is incorporated in broiler feed [29].

significantly affect immunoreactivity [26].

**4. Aflatoxins occurrence in animal products**

Another recent study assumes that aflatoxins could compromise the macrophages functions; in particular, co-exposure to AFB1, AFB2, AFM1 and AFM2 may exert interactions which can

When focusing on how mycotoxins play a role in food safety, attention should be limited to mycotoxins that are known to be transferred from feed to food of animal origin, as this food represents a significant route of exposure for humans [27]. Apart from their toxicological ef‐ fects in affected animals, the carry-over through animal derived products, such as meat, milk and eggs into the human food chains is an important aspect of mycotoxin contamina‐ tion. FAO has estimated that up to 25% of the world's food crops and a higher percentage of

Aflatoxin or ochratoxin residues in meat are uncommon and rarely found [28]. However, it's more common in organs especially liver. This organ may have its lipid content increased

ders, liver disease, anorexia, ataxia, tremors and death [22].

Decades of animal studies have demonstrated that chronic exposure to aflatoxins in animals can also cause growth inhibition and immune suppression [18]. Nursing animals may be af‐ fected, and AFM1 may be excreted in the milk of dairy cattle and other dairy animals. This in turn poses potential health risks to both animals and humans that consume that milk. Chronic aflatoxin exposure in animals can result in impaired reproductive efficiency, re‐ duced feed conversion efficiency, increased mortality rates, reduced weight gain, anemia, and jaundice. In the case of laying hens, aflatoxicosis causes an enlarged fatty liver and low‐ ered egg production [19].

Sex and age of animals have also an influence on AFB1 susceptibility. For instance, males are more susceptible than females and young animals of all species are more susceptible than mature animals to the effects of aflatoxin [12,16]. Feed refusal, reduced growth rate and de‐ creased feed efficiency are the predominant signs of chronic aflatoxin poisoning. In addition, listlessness, weight loss, rough hair coat and mild diarrhea may occur. Anemia along with bruises and subcutaneous hemorrhage are also symptoms of aflatoxicosis. The disease may also impair reproductive efficiency, including abnormal estrous cycles (too short and too long) and abortions. Other symptoms include impaired immune system response, increased susceptibility to disease, and rectal prolapse [12].

A study identified and quantified aflatoxins (AFB1, AFB2, AFG1 and AFG2) from poultry feed and their recovery, together with their metabolites (AFM1, AFM2, AFP1 and aflatoxicol) in litter. Hens were divided in 3 groups and fed with 2 AFB1 concentrations: 30 and 500 ppb, besides the control group. Feed samples of the 3 groups presented significant difference with AFB2 and AFG2, whereas in litter samples, there were significant differences for AFG2 in the 500 ppb group. Poultry litter had traces of AFM1, AFM2, AFP1 (can be considered as a demethylated AFB1) and aflatoxicol with no significant differences among treatments [20].

The presence of molds in foodstuffs causes the appearance of flavors and odors that reduce palatability and affect feed consumption by animals as well as reduce the nutritional value of foods. Mycotoxins, in turn, affect the digestion and metabolism of nutrients in animal production, resulting in nutritional and physiological disorders, besides a negative effect on the immune system [21].

It was reported main effects caused by aflatoxins during swine growth and termination phases. When feed was contaminated with 10-100 ppb, productivity losses without noticea‐ ble clinical signs were observed. When this level was 200-400 ppb, reduced growth and feed efficiency occurred. At 400-800 ppb of aflatoxins in feed, there were liver diseases (friable or yellow-tan liver). After 800-1200 ppb of aflatoxins administration in feed, reduction of food intake and growth was observed. Finally, at 1200-2000 ppb, jaundice, coagulopathy, anorex‐ ia and even mortality may happen. Not only swine is affected by aflatoxins but all species, being the main clinical signs and lesions reported as decreased weight gain, digestive disor‐ ders, liver disease, anorexia, ataxia, tremors and death [22].

A total of 480 poultry feed samples from Rio de Janeiro state were collected monthly during one year and analyzed, being the main fungal species found *P. citrinum* (35% of the samples) followed by *A. flavus* (25%) which is the main aflatoxin producer microorganism. AFB1 lev‐ els ranged from 1.2 to 17.5 ppb. There were no significant differences (P<0.001) between all months tested except February and March when the highest and lowest AFB1 production was found [23]. In Pakistan, a total of 216 samples of poultry feed ingredients were assayed, being found maximum 191.65 ppb for AFB1, 86.85 ppb for AFB2, 89.80 ppb for AFG2 and 167.82 ppb for AFG1. Minimum aflatoxins were produced in the winter season. The temper‐ ature varies from 10 to 45 ºC in this country, favorable to *Aspergillus* growth [24].

Recently [25], a survey reported the association of mycotoxins with hematological and bio‐ chemical profiles in broilers. The authors performed meta-analysis using data from 98 arti‐ cles, totaling 37,371 broilers. Some conclusions of this review were that mycotoxins reduced (P<0.05) the hematocrit (−5%), hemoglobin (−15%), leukocytes (−25%), heterophils (−2%), lymphocytes (−2%), uric acid (−31%), creatine kinase (−27%), creatinine (−23%), triglycerides (−39%), albumin (−17%), globulin (−1%), total cholesterol (−14%), calcium (−5%), and inor‐ ganic phosphorus (−12%). Mycotoxins also altered (P<0.05) the concentrations of alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase. The total protein concentration in blood was 18% lower (P< 0.05) in broilers challenged by aflatoxins com‐ pared with that of the unchallenged ones. The inclusion of antimycotoxin additives in diets with aflatoxins altered (P<0.05) some variables (uric acid, creatinine, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, and γ-glutamyl transferase) in rela‐ tion to the group that received diets with the mycotoxin and without the additive.

Another recent study assumes that aflatoxins could compromise the macrophages functions; in particular, co-exposure to AFB1, AFB2, AFM1 and AFM2 may exert interactions which can significantly affect immunoreactivity [26].
