Abstract
Zearalenone (ZEN) and its metabolites, alpha-zearalenol (α-ZEL) and beta-zearalenol (β-ZEL), are ubiquitous in plant materials used as feed components in dairy cattle diets. The aim of this study was to confirm the occurrence of ZEN and its selected metabolites in blood samples collected from different sites in the hepatic portal system (posthepatic–external jugular vein EJV; prehepatic–abdominal subcutaneous vein ASV and median caudal vein MCV) of dairy cows diagnosed with mastitis, ovarian cysts and pyometra. The presence of mycotoxins in the blood plasma was determined with the use of combined separation methods involving immunoaffinity columns, a liquid chromatography system and a mass spectrometry system. The parent compound was detected in all samples collected from diseased cows, whereas α-ZEL and β-ZEL were not identified in any samples, or their concentrations were below the limit of detection (LOD). Zearalenone levels were highest in cows with pyometra, where the percentage share of average ZEN concentrations reached 44%. Blood sampling sites were arranged in the following ascending order based on ZEN concentrations: EJV (10.53 pg/mL, 44.07% of the samples collected from this site), ASV (14.20 pg/mL, 49.59% of the samples) and MCV (26.67 pg/mL, 67.35% of the samples). The results of the study indicate that blood samples for toxicological analyses should be collected from the MCV (prehepatic vessel) of clinically healthy cows and/or cows with subclinical ZEN mycotoxicosis. This sampling site increases the probability of correct diagnosis of subclinical ZEN mycotoxicosis.
Highlights
Zearalenone (ZEN) is a resorcinic acid lactone produced by fungi of the genusFusarium, which, due to its structural similarity to 17β-estradiol and affinity to estrogen receptors [1], is classified as mycoestrogens
Clinical signs of ZEN mycotoxicosis were not observed during the experiment
The results of the present study should be interpreted in view of the following observations: (i) the feed administered to dairy cows was probably contaminated with very low doses of ZEN [5]; (ii) this is the first study of the type; the present findings cannot be compared with published data and have to be interpreted by extrapolation
Summary
Zearalenone (ZEN) is a resorcinic acid lactone produced by fungi of the genusFusarium, which, due to its structural similarity to 17β-estradiol and affinity to estrogen receptors [1], is classified as mycoestrogens. High-yielding dairy cows are highly susceptible to metabolic diseases such as milk fever, ketosis and rumen acidosis, which are frequently accompanied by subclinical and clinical symptoms of udder infection and decreased reproductive performance. Metabolic disorders are most frequently observed in three critical periods [3]: (i) dry period, (ii) parturition, and (iii) first 100 days of lactation. These periods are characterized by an increased risk of udder inflammation and aseptic diffuse inflammation of the laminar corium, which are indicative of compromised innate immunity, decreased acquired immunity to infectious factors [4], and higher susceptibility to undesirable substances, including secondary metabolites of molds such as ZEN and its metabolites
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