Effects of different concentrations of zearalenone and other mycotoxins found in dairy cows on milk quality indicators

The research was conducted in Lithuanian University of Health Sciences, Veterinary Academy, Food Quality Control Cathedral, Mycotoxicology lab. Research was during a period between 2017 and 2019. Fodder for the research were taken from the cow farms that operates in Lithuania. The task was to establish amount of the mycotoxins in the fodder (Aflatoxin B1, zearalenone, deoxynivalenol). The milk examples were used to determine ZEA and other quality measures for fat, protein, urea, lactose, pH, SCC, BBS). The fodder samples were tested via PLCh (Romer Labs methods). The ZEA in the milk was measured via ELISA test, RIDASCREEN® Zearalenone (R-Biopharm AG). The testing was conducted by VĮ „Pieno tyrimai“. (Lithuania). Thesis consists of: 45 pages, 16 pictures, and 4 tables. Aim of the thesis: To determine and evaluate how feed contaminated with different concentrations of zearalenone and other mycotoxins (Aflatoxin B1, deoxynivalenol) influences milk quality. According to our research, we found that the most common source of mycotoxin in raw materials was ZEA, as much as 74.29 %. And the most common mycotoxin found in compound feed was also ZEA - 93.75 %. During the research, we found that the percentage of AFL B1 and DON in the raw materials was the same - 54.29 %. In the analysis of identified mycotoxin levels, the highest concentrations of ZEA and AFL B1 were determined from feed table (ZEA - 496.25 µg/kg; AFL B1 - 2.67 µg/kg). The highest DON concentration was found in grain raw materials – 250 µg/kg. The lowest concentrations of mycotoxin DON were found in herbaceous oilseeds (43.18 ± 21.10 µg/kg), the lowest concentrations of ZEA were found in grain raw materials (217.5 ± 55 µg/kg. AFL B1 minimum concentrations were also found in grain feedstock (0.85 ± 0.2 µg/ kg). The link between TBC in milk dependency on mycotoxins in feed and the presence of the highest levels of BBS in those milk samples with high concentrations of ZEA in feed is evident. It can also be observed that the higher the ZEA concentration in the feed sample is, the higher amount of TBC in milk follows. As a result, we can assume that the TBC is proportionally high when a large amount of ZEA is detected in the sample. About 33 percent AFL B1 was found to be above 5 µg / kg in the samples and 66.7 ± 0.1% in samples with mycotoxin AFL B1, the TBC content was greater than 120 ± 4 thsd./ml. The highest levels of SCC were found in the milk samples with high ZEA concentrations in feed. It can also be observed that the higher the ZEA concentration in the feed sample is, the higher the amount of SCC in milk follows. Therefore, based on the test, we can say that the increase in SCC is influenced by the higher ZEA content. The SCC correlation with ZEA detected very strong positive (r=0,902), with DON - strong positive (r=0,801) and with AFL B1 weak positive (r=0,342). According to the studies, 66.6 ± 0.1 % of the total number of samples containing mycotoxin AFL B1 were above 300 thsd. / ml. ZEA correlation with milk fat – average positive (r=0,502), milk proteins – very weak positive (r=0,196), milk lactose - very weak positive (r=0,142). AFL B1 correlation with milk fat average negative (r= -0,431), milk proteins – very weak negative (r=-0,137), milk lactose - very weak positive (r=0,175). When the ZEA concentration is greater than 500 µg/kg, urea levels range from 20 mg/100 ml (ZEA content 700 µg/kg) to 30 mg/100 ml (ZEA content 1000 µg/kg). Research has shown that 16 % ZEA mycotoxin was detected in the milk samples. The highest ZEA concentrations in milk samples were determined from farm 5 and 9, respectively 0.3 µg/l and 0.4 µg/l. The minimum ZEA concentration in the milk sample was determined in sample 4 (0.08 µg/l). Correlation with ZEA concentration detected in feed ZEA concentration in milk sample are very strong negative ( r=-0,90)