*2.1.1. Aflatoxins and milk production*

through the bile. The liver is considered the target organ for aflatoxins. At this level, the metabolization of mycotoxins takes place under the action of microsomal enzymes. The reaction products are eliminated from the organism through excretion products (feces and urine)

ism of some animals, have demonstrated both the elimination in significant quantities of the mycotoxin from the organism in the first 24 hours, as well as the accumulation of the residual quantity in different organs (muscles, stomach, liver, heart etc.), accumulation conditioned by

Naturally, ruminants seem to be more resistant to the action of aflatoxins compared to other species of animals, although the clinical signs of aflatoxicosis have been observed in cows, such as: the reduction in the ingestion of food, the decrease in the production of milk, the affliction of the hepatic function. The chronic exposure to the ingestion of aflatoxin determines an inefficient feeding, depression of the immune system and the reduction of the reproductive function [6].

tive tract through passive diffusion. Aflatoxins, like other mycotoxins, induce severe hepatic

The pathologic modifications are more alarming in dairy cows, with high production, which are

the replication and transcription of DNA and inhibits the synthesis of RNA and proteins. The metabolic products of aflatoxin act on the chromatin inhibiting the transcription of genes and RNA polymerase, which as a result produces a decrease in the concentration of RNA and pro-

in blood, in plasma, being linked especially to albumins. Aflatoxins are oxidized in the liver with formation of very reactive molecules, capable of binding the nucleic acids or functional proteins. This hepatic bioactivation has a considerable importance for animal health due to the active metabolites that form *in situ*, at tissue level. The metabolization of aflatoxins at hepatic level takes place under the action of the microsomal enzymes, the most active of these being P450.

while small quantities can be distinguished in feces which confirms the rapid absorption of

ucts is similar to that of the parent molecule. Aflatoxins affect the ruminal function through the reduction of ruminal motility, the capacity of digesting celluloses, of producing volatile

The ruminal juice and, moreover, the bacteria population from the cow and sheep rumen

is found in large quantities in milk [11]. Auerbach et al. have observed that adding 9.5 ng

/ml ruminal liquid did not alter *in vitro* the digestion of alfalfa and did not influence the

does not have the capacity to convert aflatoxins in other metabolites except for AFM1

production of volatile fat acids while, in another study, adding a dose of 1 μg AFB1

lighted the lowering of the ruminal capacity of producing the acids [12].

which explains its incredibly strong carcinogenic effect. Approximately 90% of AFB1

is a strong inhibitor of the protein synthesis which blocks *in vivo*

effectively couples with the DNA and causes irreversible mutations,

, the metabolites are quickly found in urine and milk,

is minor and the toxicity of the metabolic prod-

marked with C14, in the organ-

are absorbed in the diges-

is present

which

/ml high-

and milk in unmodified form as well as metabolites.

88 Ruminants - The Husbandry, Economic and Health Aspects

the dosage of mycotoxin ingested.

more sensitive to toxins. AFB1

tein synthesis. *In vitro*, AFB<sup>1</sup>

AFB<sup>1</sup>

AFB<sup>1</sup>

After the oral administration of AFB1

fat acids and proteolysis [10].

In general, the ruminal degradability of AFB1

in the digestive tract and hepatic metabolism [9].

The studies regarding the distribution and metabolism of AFB1

The lipophilic mycotoxins with a small molecular mass like AFB1

dysfunction confirmed through biochemical tests in numerous studies [7, 8].

The transformation of AFB1 from fodder in AFM<sup>1</sup> in milk is realized following a process of hydroxylation. AFM1 and AFM<sup>2</sup> are metabolites (hydroxylated forms) of AFB1 and AFB<sup>2</sup> found in milk. Other metabolites identified in cow milk are: AFM4 , AFQ<sup>1</sup> and aflatoxicol [17].

At dairy cows, the absorption of AFB1 in the digestive tract is rapid and complete, which explains its almost immediate transfer in the milk, under the shape of AFM1 [9]. Although many researchers have concentrated their attention on the study of AFM1 from public health reasons, its production represents between 1 and 3% of ingested AFB1 , with an average of 1.7% [18, 19]. Other studies have reached the conclusion that certain quantities of AFB1 in the food of dairy cows (13 mg impure AF/day, over 7 days) can induce the decrease in production, without the evident clinical sign of disease. The transfer rate of AFB1 from fodder to milk has been variable, with values comprised between 0.3 and 2.2% [20]. Milk production and body weight returned to normal limits within the next 5–8 days from removing the contaminated fodder.

For preventing the risk of transmitting AFB1 to the milk, the superior limit for the content of this mycotoxin in the fodder of dairy cows with a production of 20 kg milk/day, after ingesting 6 kg of contaminated fodder/day has been evaluated at 5 μg AFB1 /kg [21].

It was administered to a lot of lactating cows, in their food ration, corn contaminated with 120 μg AF/kg fodder. As a result, it was discovered the apparition of reproductive disorders, health problems, as well as the decrease in milk production. After removing the contaminated corn from the ration, the milk production rose to 28% within 3 weeks [22].

Diaz et al. [9] affirm that AF appear in milk after approximately 12 hours from the oral administration of AFB<sup>1</sup> , the maximum quantity being registered after 24 hours from ingesting the aflatoxin.

The mathematical relationship between the ingested quantity of AFB1 and the quantity found in the milk is:

$$\text{AFM}\_1 \text{(ng/kg milk)} = 10,95 + 0.787 \,\text{X} \tag{1}$$

*Anatomopathologic modifications.* At the anatomopathological exam it can be observed: jaundice, generalized hemorrhage, hemorrhagic gastroenteritis, intestinal ulcers, hepatic necrosis, steatosis, hepatic fibrosis, hepatomegaly, cirrhosis, ascites, hydrothorax, thickening of the

Dairy Cows Health Risk: Mycotoxins http://dx.doi.org/10.5772/intechopen.72709 91

*Histological modifications*. At the histologic exam, we can see perineural hemorrhage, perirenal edema, pioencephalitis with eosinophilic infiltrations and, in the case when it crosses the placental barrier, AF produces hepatic and digestive micro-lesions starting from the intrauterine life [24]. The most important action of the aflatoxins is considered to be the carcinogenic one, as well as the accusation of the preexisting tumoral formations. Neoplastic lesions are produced especially at hepatic level, but also at the level of the digestive tube, with lungs, kidneys metastases etc. Neathery et al. have observed that, in the situation when food is administered containing

 (0–5 ppm) and zinc (40–640 ppm), at calves, they showed some of the characteristic clinical signs of aflatoxicosis: reduction of food ingestion, lowering of live weight, reduction in pulse values and respiratory rhythm; no other anatomopathological modifications were seen

*Presumptive diagnosis* is established based on the epidemiologic enquiry, clinical examination and anatomopathologic exam, while the certainty diagnosis is done on the basis of paraclinical examination (drop in vitamin D in the liver and the increase in alkaline phosphatase with return to normal before death) and of mycologic and mycotoxicologic examination of the fodder.

Ochratoxins are compounds developed by different species of *Penicillium* (*P. viridicatum, P. commune, P. purpurescens)* and *Aspergillus* (*A. ochraceus, A. alliaceus, A. melleus,* etc.) which

Ochratoxins A (OTA), B (OTB), C (OTC), D are a group of compounds in whose chemical structure L-fenilalanin is coupled through an amidic link with an isocumarinic derivative. The production of these mycotoxins is frequent in molded or overheated fodder and is favored by the presence of oligoelements, a temperature of 20–28°C and a humidity of 18–19% at wheat, in the case of *P. viridicatum* or 22% in corn. In laboratory conditions, most strains of *A, ochraceus* produce OTB and OTC, while in natural environment conditions, the most frequent is

OTA is passively absorbed, in unionized form, at the digestive tube level, especially at the level of the short intestine level, at a pH of 7.04. After OTA's penetration of the organism, the mycotoxin links itself to the albumines in the plasma and starts rapidly metabolizing, depending on the animal species. Among the organs, OTA's highest affinity is for the liver and kidney. OTA has the strongest inhibitor effect on animal growth, determining the exces-

The halving time of OTA in studies on monkeys was 840 hours, or several days in the case of pigs [32] and 3 hours in chicken [23]. The most important transformation takes place at hepatic level, where OTA is metabolized through hydroxylation in 4-hydroochratoxin A,

contaminate cereal grain, vegetables and combined forage.

OTA. Its precursors can also be seen in culture media [23].

metabolite eliminated by the kidney [31, 32].

sive accumulation of glycogen in the liver of afflicted animals [31].

bladder walls and gall bladders [29].

in the liver or other organs [30].

**2.2. Ochratoxins**

AFB<sup>1</sup>

where X = μg AFB1 ingested/day.

Similar studies have shown approximately 90% of AFM1 present in the blood can be determined in the plasma and is found afterwards in the milk and urine [23].

The FDA limits aflatoxins to no more than 20 ppb in lactating dairy feeds and to 0.5 ppb in milk; in Europe, the regulatory levels of AFB1 are 20 ppb for dairy feeds and 0.05 ppb in milk.

## *2.1.2. Aflatoxicosis*

The aflatoxicosis is an acute or chronicle mycotoxicosis of mammals, as well as birds, produced by aflatoxins.

*Etiologic agent, toxicity.* Aflatoxicosis is induced by the aflatoxins produced by some species of fungi such as *Aspergillus flavus, A. parasiticus, A. niger, A. ochraceus, Penicillium puberulum, P. citrinum* and *Rhizopus spp.* From these, the main aflatoxin producers are *A. flavus* and *A. parasiticus*. Mycotoxins, as well as their metabolic products, work on the act on the chromatin, inhibiting the synthesis of the nucleic acids DNA and RNA from the hepatic cells and, at the same time, on the cellular membranes and membranes of the different intracytoplasmic structures.

*Clinical signs.* Aflatoxins produce disorders at the level of the central nervous system, digestive system, cardiovascular system and hematopoietic organs.

Aflatoxicosis evolves under acute, sub-acute and chronic form.

*In acute form,* it can be observed clinically: inappetence, anorexia, nervous depression, ataxia, dyspnea, and melena, anemia, while in sub-acute form: hemorrhagic enteritis, subcutaneous hematoma and jaundice.

*In chronicle form,* it can be observed: reduction of growth, rough and pale hair coat, anemia, jaundice, slower growth, apathy, diminished appetite, teeth grinding, fixed stare, circular movement, ataxia, diarrhea, rectal prolapse at mammals [24]; reduced resistance to diseases and interferes with vaccine induced immunity in livestock [25].

The toxic effects depend on: the dosage of mycotoxin ingested, the way of ingestion/administration, duration of exposure, nutritive quality of the ration, species and animal age. The calves, fresh cows or dairy cows in early lactation are most affected because their immune system is suppressed. Alongside *Aspergillius flavus, A. parasiticus*, producers of aflatoxin and *Aspergillius fumigatus* producer of tremorgens or viritoxin, fumagillin, encountered both in fibrous fodder, as well as silos, is considered as pathogen agent, being associated with the Mycotic Hemorrhagic Bowel Syndrome (HBS) at dairy cows [26].

Adult taurines and sheep are the least sensitive to the action of the mycotoxin. It is considered though that with the ingestion of at least 100 ppb aflatoxin/day, ruminants (both meat and dairy cattle) are exposed to the risk of the development of aflatoxicosis which debuts with: the reduction of food ingestion, diminished live weight, lowering of milk production, decline of the efficiency of the reproductive capacity [27, 28].

*Anatomopathologic modifications.* At the anatomopathological exam it can be observed: jaundice, generalized hemorrhage, hemorrhagic gastroenteritis, intestinal ulcers, hepatic necrosis, steatosis, hepatic fibrosis, hepatomegaly, cirrhosis, ascites, hydrothorax, thickening of the bladder walls and gall bladders [29].

*Histological modifications*. At the histologic exam, we can see perineural hemorrhage, perirenal edema, pioencephalitis with eosinophilic infiltrations and, in the case when it crosses the placental barrier, AF produces hepatic and digestive micro-lesions starting from the intrauterine life [24].

The most important action of the aflatoxins is considered to be the carcinogenic one, as well as the accusation of the preexisting tumoral formations. Neoplastic lesions are produced especially at hepatic level, but also at the level of the digestive tube, with lungs, kidneys metastases etc. Neathery et al. have observed that, in the situation when food is administered containing AFB<sup>1</sup> (0–5 ppm) and zinc (40–640 ppm), at calves, they showed some of the characteristic clinical signs of aflatoxicosis: reduction of food ingestion, lowering of live weight, reduction in pulse values and respiratory rhythm; no other anatomopathological modifications were seen in the liver or other organs [30].

*Presumptive diagnosis* is established based on the epidemiologic enquiry, clinical examination and anatomopathologic exam, while the certainty diagnosis is done on the basis of paraclinical examination (drop in vitamin D in the liver and the increase in alkaline phosphatase with return to normal before death) and of mycologic and mycotoxicologic examination of the fodder.
