SURVEY AND CONTROL OF MYCOTOXIGENIC MOULDS IN POULTRY FEEDS AND EFFECT OF MYCOTOXIN ON PERFORMANCE OF POULTRY

Abstract

Studies on the moulds and mycotoxin contaminating poultry feeds in South-Western Nigeria were conducted in May- October 2008 and November –April 2009. A total of 300 samples of finished commercial poultry feeds (layers and broilers mash) were examined for mycotoxin and mould contamination. Extraction of mycotoxin from feed samples was carried out both by the aqueous acetone and chloroform extraction methods. The extracts were qualitatively examined by quick screening and thin layer chromatographic method. The effect of storage conditions on the growth of mould and mycotoxin levels in the poultry feeds using different packaging materials were evaluated while the nutrient composition of the feed samples were also investigated using conventional methods. Toxicological studies were carried out using 4 weeks old broilers and 32 weeks old layers which were housed in groups of fifteen (five per group) in stainless steel cages. There was one positive control group which was maintained on basal diet that was free from mycotoxin contamination while the other groups were fed with feed contaminated with mycotoxigenic moulds containing 250μl, 500μl and 750μl of toxigenic Aspergillus flavus, A. parasiticus, F. verticilloides and A. ochraceus and aflatoxin, fumonisin and Ochratoxin standards respectively. The birds were observed for signs of toxicity for 4 weeks. Histological assay were conducted on the organs (gizzard, liver and kidney) the birds. The initial body weights of the birds were recorded at 7 days interval up to the end of the experiment. The birds were immunized against gumboro and ranikhet disease (BCRD) on the 5th and 18th day and also with Nobilis gumboro D-78 on day 11 and 21. Blood samples were taken by cardiac puncture from birds in each group, and heparin was used as iii anticoagulant. Samples were taken to the laboratory under refrigeration. The hematology parameters of birds like Red blood cell (RBC), Hemoglobin (Hb), Packed cell volume (PCV), and White blood count (WBC) heterophils, monocytes, lymphocytes and eosinophil count were determined. Evaluation of the effect of mycotoxin contamination on egg production, egg performance, feed intake and egg qualities like albumin, yolk height and weight collected from layers were also determined together with metabolism of mycotoxin in the eggs and stability of the toxin in the eggs to boiling process. Essential oils extracted from nine medicinal plants (Cymbopogon citratus, Allium sativum, Ocimum basilica, Zingiber officialis, Citrus limon, Citrus aurantifolia, Citrus sinensis, Azadirata indica and Pimenta racemosa) were screened for their activity against toxigenic strains of Aspergillus flavus, Aspergillus parasiticus, Fusarium Verticilloides and A. ocheracus by disc diffusion method. Minimum inhibitory concentrations (MIC) of oils against the toxigenic moulds was analyzed by agar dilution method and minimum fungicidal concentration (MFCs) data obtained by the broth micro dilution method. Also extracts from other plants (Borreria verticullata, Lactuca capenisi, Colocasia esculenta, Jatropha gossy and Ageratum conyzoide) leaves part were investigated in vitro and in vivo for antifungal activities against Aspergillus flavus, Aspergillus parasiticus, Fusarium verticilloides and A. ocheracus. The experiment was laid out in a completely randomized design (CRD). Each of the treatment was replicated three times under laboratory conditions and data obtained were subjected to analysis of variance. Duncan New Multiple Range and Turkey Test were used to separate the means.