Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS

1 st WorkshopXIII International Feed Technology SymposiumF. verticillioides and one unidentified Aspergillus species. The dominant fungal generain powdered calf feed mixture were potentially toxigenic Fusarium (F. oxysporum, F.subglutinans and F. verticillioides) and Aspergillus (A. flavus, A. niger A. ochraceus andA. versicolor) as well as ubiquitous Acremonium (A. fusidioides and A. rutilum).The dominance of these fungi is not surprising because minimum moisture content fortheir growth is ranging from 15% (A. ochraceus) to 18% (A. flavus and Fusarium spp.)[10]. Identified molds are common contaminants of fodder ingredients and completemixtures in the region of Banat (A.P. Vojvodina, R. Srbija) [2].The mycotoxin of greatest concern for dairyman is aflatoxin B1 (AFL B1), althoughothers that are being studied frequently and which also appear to be of concern toruminant animals are fusariotoxins: zearalenone (ZON) and type A trichothecenes (DASand T-2 toxin) (Table 4).Table 4. Presence of mycotoxins in calf feed mixtures during storage (mg/kg)Powdered mixturePelleted mixtureMycotoxin(mg/kg)Day Day Day Day Day Day Day Day0 45 90 150 0 45 90 150Aflatoxin B1 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.Zearalenone n.d. n.d. 0.736 0.368 n.d. n.d. 0.442 0.221Trichothecenes(T-2)0.337 n.d. n.d. n.d. 0.337 n.d. n.d. n.d.Trichothecenes(DAS)n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.Legend: n.d. - not detected (aflatoxin B1 < 0.0004 mg/kg, zearalenone < 0.0123 mg/kg,DAS and T-2 < 0.04 mg/kg)Aflatoxin B1 (AFL B1) was not detected at all during present investigation, althoughAspergillus flavus, potential producer of this mycotoxin, was continuously found in thepowdered calf mixture from the production day (day 0) until the end of the storage (day150) (Table 4). This finding can be explained by the fact that A. flavus isolates fromSerbian commodities are not at all or are weak producers of AFL B1.Zearalenon (ZON) was found only after 90 and 150 days of storage of both types ofcalf feed. Most likely, during storage the moisture content arised from initial 11.29% i.e.11.13% to 17% or more – the minimal value necessary for mycotoxin production. Thefindings of this mycotoxin can be explained by the presence of molds F. oxysporum andF. subglutinans during 150 days of storage in powdered sample i.e. F. subglutinans inthe pelleted sample at the production day (0 day) (Table 3). After 90 days of storage,higher concentrations of ZON in powdered sample (0.736 mg/kg) then in pelleted one(0.442 mg/kg) can be explained by the fact that probably higher inoculum of Fusariumconidia was present in powdered calf mixture. The absence of ZON until the 90 days ofstorage was according to our mind the consequence of longer time period necessary forthe production of this fusariotoxin.Type A trichothecenes (T-2 and DAS). Only T-2 toxin was detected during presentinvestigation at the beginning of storage and in the same quantity in pelleted andpowdered sample (0.377 mg/kg). This trichothecene was probably produced before115