الفهرس 
Introduction
Aim of the workOnly 14 pages are availabe for public view
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Abstract
During the present study, One hundred and thirteen feed ingredient samples of maize (n=64) and sorghum (n=49) were collected from Assuit Governorate during the period from September 2015 to October 2016. Freshly harvested samples were collected directly from farms during harvesting season (40 maize and 25 sorghum samples). Stored samples were collected from storage sites owned to the farmers; 24 aggregate samples from each of maize and sorghum during the period from January to October 2016.
1- Two different isolation media were used to assess the mycological status of the samples. Dichloran rose Bengal chloramphenicol agar (DRBC) for general isolation of fungi, and Aspergillus flavus and parasiticus agar (AFPA).
2- The moisture contents of samples and aflatoxigenic ability of the isolates were investigated.
3- Aflatoxins were detected in samples using thin layer chromatography (TLC) methods for qualitative analysis, and positive samples were quantified by ultra-performance liquid chromatography (UPLC).
The main results can be summarized as follow
1-The mean moisture content were 44.99%±11.38, 9.50±1.03, 7.04%±1.59 and 7.26%±2.27 for the freshly harvested maize samples, freshly harvested sorghum samples, stored maize and stored sorghum respectively.
2- A total of 65 species assigned to 26 genera were isolated from all samples investigated (40 freshly harvested maize samples, 25 freshly harvested sorghum samples and the stored maize and the stored sorghum (24 samples each)).
3- The total count of fungi isolated from freshly harvested maize samples, freshly harvested sorghum samples, stored maize and stored sorghum samples ranged from 1-34, 12-34, 8-32 and 9-41 CFU respectively on DRBC agar and ranged from 2-32, 8-34, 11-36 and 14-34 CFU on AFPA agar.
4- The mean count of fungi in the stored maize samples decreased gradually after 3 months of storage till the 9th month of storage then increased in the last period of storage, while in the stored sorghum samples the mean count increased gradually after 3 months of storage till the 9th month of storage then decreased in the last period of storage.
(1) Results of the freshly harvested maize samples
1- Aspergillus was the most common genus being isolated from 85% and 90% of samples on the DRBC and AFPA agar respectively. Alternaria, Fusarium and Penicillium were isolated from 42.5%, 35% and 32.5% of the samples on DRBC agar and from 40%, 25% and 27.5% on AFPA agar respectively.
2- On DRBC agar, A. flavus and A. parasiticus contaminated 47.5%, and 7.5% of the samples while contaminated 52.5% and 7.5% on AFPA agar.
3- Fifteen isolates out of the 24 A. flavus isolates (62.5%) were aflatoxin producers on CAM while only 53.33% of the positive isolates had the favorable conditions to produce aflatoxins in samples under the field conditions (with levels ranging from 1.73-111.76 ppb).
4- Total aflatoxins (TAFs) levels ranged from 1.73 – 111.76 ppb with a mean ± SD of 31.56±29.95 ppb. AFB1 ranged from 1.73 – 110.11 ppb with a mean of 28.21±27.30 ppb. AFB2 ranged from 0.08 – 20.7 ppb with a mean of 5.70±6.88 ppb. AFG1 ranged from 0.30 – 1.05 ppb with a mean of 0.45±0.35 ppb.
(2) Results of the freshly harvested sorghum samples
1-Alternaria and Aspergillus were the most common genera being isolated from 100% and 88% of the analyzed samples on DRBC and from 100% and 84% of samples on AFPA respectively. Fusarium and Penicillium were isolated from 76% and 36% of the samples on DRBC agar and from 68% and 44% of samples on AFPA agar respectively.
2- A. flavus contaminated 80% of the samples on both DRBC and AFPA agar while A. parasiticus isolates was not detected.
3-Thirteen (59.09%) out of the A. flavus isolates were positive to aflatoxins production on CAM while 84.62 % of the positive isolates had the favorable conditions to produce aflatoxins in samples under the field condition.
4-Total aflatoxins (TAFs) levels ranged from 1.84 – 122.72 ppb with a mean ± SD of 50.75±45.95 ppb. AFB1 ranged from 1.84 – 116.89 ppb with a mean of 42.15±36.10 ppb. AFB2 ranged from 0.12 – 27.22 ppb with a mean of 14.99±18.86 ppb. AFG1 ranged from 0.08 – 9.76 ppb with a mean of 4.12±6.38 ppb.
(3) Results of the stored maize samples
a) ON DRBC agar:
1- After 3 months of storage, Aspergillus spp. was the most common fungus recovered from 100% of the samples. Fusarium, Alternaria and Penicillium contaminated only 33.33%, 16.67% and 16.67% of the samples.
2-After 6 months, Aspergillus spp. and Talaromyces duclauxii were the most common fungi that recovered from 100% and 83.33% of the samples. Penicillium, Alternaria and Fusarium contaminated 33.33%, 16.67% and 16.67% of the samples.
3- After 9 months, Aspergillus was the most common fungus. It was recovered from 100% of the samples. Fusarium, Penicillium and Alternaria contaminated 33.33%, 33.33%, and 16.67% of the samples.
4- After 12 months, the most common genera were Aspergillus and Cladosporium (83% of the samples each). Alternaria, Penicillium and Fusarium contaminated 50%, 50% and 16.67% of the samples.
5- A. flavus contaminated 100%, 66.67%, 50% and 83% of samples after 3, 6, 9 and 12 months respectively. A. parasiticus was isolated from 16.67% and 33.33% of samples after 6 and 9 months of storage.
b) On AFPA agar
1- After 3 months, Aspergillus was the most common fungus contaminating 100% of the samples. Fusarium, Alternaria and Penicillium contaminated 50%, 33.33% and 16.67% of the samples.
2-After 6 months, Aspergillus was the most common fungus contaminating 83.33% of samples. Penicillium, Fusarium and Alternaria contaminated 66.67%, 16.67% and 16.67% of the samples.
3- After 9 months, Aspergillus was the most common fungus contaminating 100% of the investigated samples. Alternaria, Fusarium and Penicillium each contaminated 33.33% of the samples.
4- After 12 months, Aspergillus was the most common fungus and contaminating 83.33% of samples. Alternaria and Penicillium each contaminated 33.33% of the samples while Fusarium was not detected.
5- A. flavus contaminated 100%, 66.67%, 66.67% and 83% of samples after 3, 6, 9 and 12 months respectively while A. parasiticus was isolated from 16.67% and 33.33% of samples after 6 and 9 months of storage.
c) Eighteen (90%) isolates out of the 20 A. flavus isolates were aflatoxin producers on CAM. 77.78% of the positive A. flavus strains had the favorable conditions to produce aflatoxins in samples during storage.
d) Total aflatoxins (TAFs) levels ranged from 1.97-254.81 ppb with a mean of 42.65±59.43 ppb. AFB1 ranged from 1.97-215.42 ppb with a mean of 36.90±49.56 ppb. AFB2 ranged from 0.13–38.92 ppb with a mean of 9.30±13.63 ppb. AFG1 ranged from 0.21–0.52 ppb with a mean of 0.39±0.13 ppb. The mean levels of the TAFs contaminated the samples collected after 3, 6, 9 and 12 months of harvesting were 11.72±7.64, 35.38±24.14, 107.73±128.17 and 47.49±30.90 ppb respectively.
(4) Results of the stored sorghum samples
a) ON DRBC agar
1- After 3 months of storage, Alternaria alternata, Aspergillus spp. and Fusarium spp. were the most common genera that recovered from 100% of the samples and constituted 45.75%, 30.72% and 7.84% of the total amount of CFUs respectively. Penicillium was isolated from 16.67% of samples comprising 1.96% of the total propagules.
2-After 6 months, Alternaria alternate and Aspergillus spp. (4 species) were the most common genera, contaminating each 100% of samples. Fusarium spp. and Penicillium spp. contaminated 83.33% and 50% of samples respectively.
3- After 9 months, Alternaria alternata and Aspergillus spp. contaminated 100% and 83.33% of samples. Fusarium and Penicillium contaminated 66.66% and 33.33% of the investigated samples.
4- After 12 months, the most common genera were Alternaria alternata and Aspergillus spp. that were isolated each from 83.33% of the investigated samples. Species of Fusarium and Penicillium contaminated 33.33%, 16.67% of the samples.
5- A. flavus contaminated 50%, 83.33%, 16.67% and 50% of samples after 3, 6, 9 and 12 months respectively while A. parasiticus was isolated from 33.33%, 50% and 16.67% of samples after 3, 9 and 12 months of storage.
b) On AFPA agar
1- After 3 months, Alternaria spp. and Aspergillus spp. were contaminated 100% of the samples while species of Fusarium and Penicillium contaminated 66.67%and 16.67% of the samples.
2-After 6 months, Alternaria alternata, Cochliobolus spp. and Fusarium spp. were recovered each from 100% of samples while species of Aspergillus and Penicillium were contaminated 66.66% and 33.33% of samples respectively.
3- After 9 months, Alternaria altarnata and Aspergillus spp. were the most common fungus contaminating 100% of the investigated samples. Species of Fusarium and Penicillium contaminated 50% and 16.67% of the samples respectively.
4- After 12 months, Alternaria alternata was recovered from 100% of samples while Aspergillus spp. was recovered from 66.67% of samples. Species of Penicillium and Fusarium contaminated 50% and 33.33% of the samples respectively.
5- A. flavus contaminated 66.67%, 50%, 50% and 33.33% of samples after 3, 6, 9 and 12 months respectively while A. parasiticus was isolated from 16.67% and 50% of samples after 3 and 9 months of storage.
c) Eleven (64.71%) of the A. flavus isolates were gave blue florescence on the CAM while 90.91% of the positive A. flavus strains had the favorable conditions to produce aflatoxins in samples during storage.
d) Total aflatoxins (TAFs) in stored sorghum samples levels ranged from 9.53 – 241.70 ppb with a mean of 63.38±60.98 ppb. AFB1 ranged from 7.34 – 209.96 ppb with a mean of 54.87±54.70 ppb. AFB2 ranged from 2.07 – 61.89 ppb with a mean of 22.13±21.48 ppb. AFG1 ranged from 0.34 – 20.53 ppb with a mean of 4.15±7.29 ppb. The mean levels of the TAFs contaminating the samples collected after 3, 6, 9 and 12 months of harvesting were 39.51±736.19, 70.79±110.31, 76.60±98.72 and 63.38±60.98 ppb respectively.
The results of our investigations revealed that, sixteen samples (40%) out of the forty freshly harvested maize samples were positive for aflatoxins contamination. Twenty-three (92%) of the freshly harvested sorghum samples (n=25), 17 samples (70.83%) of the stored maize samples (n=24) and 22 samples (91.67%) of the stored sorghum samples (n=24) were contaminated with aflatoxins. The percentage of samples that exceed the permissible limits of the Egyptian regulation (20 µg/kg) was 43.75% (7 of 16 positive samples), 69.57% (16/23), 62.94% (9/17) and 50% (11/22) of the freshly harvested maize, the freshly harvested sorghum, the stored maize and the stored sorghum samples respectively. The higher percentage of aflatoxins contamination exceeding the permissible levels were found in the fresh sorghum samples (64% of the total samples) followed by the stored sorghum samples (45.83%) and the stored maize samples (37.5%) then the freshly harvested maize (17.5%).