*2.2.1. Ochratoxicosis*

At the level of the digestive tube, where afterwards it is also absorbed, another important metabolite is formed, OT-α, which is finally eliminated through the digestive system or the kidneys. Other metabolites formed in the organism follow an enterohepatic circuit after which

Höhler et al. affirm that sheep fed with fodder containing various concentrations of OTA multiple values were recorded. Thus, at 2 ppm added OTA in food, there were significant concentration of OTA and OTA-α in the sanguine serum (10 and 3 ng/ml) and much higher concentrations for both mycotoxines at 5 ppm added OTA in food (80 and 15 ng/ml) [33].

The quantity of mycotoxin degraded by the intestinal and ruminal microsymbionts is dependent on the quantity of concentrates from food, the absorption of mycotoxins being higher at a larger content of starch in the food compared to fibers. From the total quantity of OTA ingested, approximately 70% of it is eliminated as OTA – α (9% in feces and 61% in urine) compared to the underrated OTA form (1% in feces and 3.8% in urine) [9]. Recent studies have shown the ability of OTA to disturb the cellular signal and to influence the viability and

OTA was determined in quantity of 2.2 μg/kg in the oat assay and in amount of 3.2 μg/kg in the bran assay. In the case of this mycotoxin, the results obtained revealed a quantity of 0.1 ng/ml in blood serum, 0.018 ng/ml in milk and 0.009 ng/ml in urine. Although it can be observed that from the 5.4 μg/kg ingested OTA, 1.8% were transferred in the blood serum, 0.3% in milk and 0.1% in urine, the conclusion regarding the conversion rate is uncertain, as different studies regarding the absorption and excretion of OTA and OTA-α at ruminants have shown the major influence of the type of food on the metabolites transfer to blood, milk and urine. The protozoa population at the rumen level is largely influenced by the type of alimentation of the ruminants. For example, the transformation of OTA in OTA- α is favored by feed rich in starch more than one rich in fibers [23, 35]. In a study on sheep, Blank et al. administered OTA through wheat contaminated with mycotoxins, at a base ration of 70% concentrated feed and 30% silo. The study showed that a large part of the OTA quantity remained undegraded and was detected in the sheep serum (from 1.5 to 18 μg OTA/kg BW/day), regardless of the OTA level in the food, while the quantity of mycotoxin excreted in the urine remained almost constant (6–8% of the ingested dose), regardless of the food dose. Alongside OTA, small OTA-α were detected in the serum (from 0.5 to 1.6 μg OTA-α/kg BW/day), directly proportional with

An important aspect of the metabolization of OTA in the organism is represented by the renal absorption at the level of the proximal tubes (2/3) and at the level of the distal tubes and collector channel (1/3). This phenomenon takes place due to the disturbance of pH homeostasis at cellular level of the nephron walls, which affects the acid–base transepithelial transport and determines the acidification of urine. The latter favors the reabsorption of OTA leading to the accumulation

Protozoa are considered organisms with a major role in degrading OTA to OTA-α. Other factors that can significantly influence the metabolic rate of OTA in the ruminant organism are: the animal age, genetic structure, health of the ruminal microsymbionts, alimentary ration

of the mycotoxin in the organism through the reduction of the elimination rate [37, 38].

they are also eliminated through feces and urine [32].

92 Ruminants - The Husbandry, Economic and Health Aspects

proliferation of cells [34].

the of the quantity of OTA in the food [36].

structure.

Due to the detoxifying capacity of ruminal symbionts for OTA, ruminants appear to be more resistant to the action of ochratoxins compared to monogastric animals. This capacity is the more evident the healthier the population of microsymbionts, especially protozoa. An alimentation rich in concentrated fodder affects the level of ruminal pH, consequently affecting the protozoa population and, implicitly, the capacity of metabolizing mycotoxins, in this case OTA. Moreover, after the administration of a dose similar to the one naturally found in fodder, OTA and OTA-α were not detected in milk, which is explained by the degradation of the ochratoxin in the rumen by the microsymbionts.

From the clinical signs of ochratoxicosis at ruminants, we distinguish the development of the pulmonary edema and the damaging of the animal health up to its death at OTA concentrations of over 3 ppm/kg in the fodder. At the same time, studies have shown that OTA does not cross the placenta barrier in the case of the oral administration of mycotoxin in reduced quantities (0.38 mg OTA/kg), although this was detected in the cow milk, as well as in ilk from other animals (pig, rabbit, rat).
