Occurrence of mycotoxins in fish feeds in Nyeri, Kenya 16 th - - PowerPoint PPT Presentation

BIOTOXINS AND BIOACTIVE SUBSTANCES

Occurrence of mycotoxins in fish feeds in Nyeri, Kenya

16th International Conference on Chemistry and the Environment

18th June 2017 to 22nd June 2017

1 Norwegian University of Life Sciences

Presenter: Mwihia, E.W.

Mwihia, E.W.; Mbuthia, P.G.; Gunnar, E.S.; Gathumbi, J.K.; Maina, J.M.; Mulei, I.R. and Lyche, J.L.

• Began in 1920s
• Production inconsistent through the years but rose considerably in 2010
• GoK injected millions of dollars into commercial fish farming through ESP
• Fish farming characteristics:

– extensive to semi intensive – Tilapia but also catfish, rainbow trout – Earthen ponds (mostly not lined) – Water source - rivers or natural springs

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Introduction – aquaculture in Kenya

• Mycotoxins – secondary metabolites produced by fungus
• invade organic substrates when conditions are favourable (moisture and temperature)
• Humans and animals - highly toxic, cancer-causing, immune suppressive, growth retardant,

death

• Exposure is mainly through consumption of contaminated foods and feed
• In fish, mycotoxins e.g. aflatoxins cause

– poor growth, anaemia, impaired blood clotting, sensitivity to bruising, damage to liver and

• ther organs, decreased immune responsiveness and increased mortality
• Major concern – Aflatoxin, Fumonisin, Deoxynevalenol, Zearelonone, Ochratoxin, T
• 2, HT
• 2

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Introduction - Mycotoxins

• Specific objectives:

1. To quantify total aflatoxin levels present in fish feed used in Nyeri, Kenya

Total – Aflatoxins B1, B2, G1 and G2

• 2. To screen for other mycotoxins that may be present in fish feed used in Nyeri, Kenya
• 3. To document the knowledge, attitudes and practices associated with aflatoxin

contamination of fish feed in Nyeri, Kenya.

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Objectives

• Mycotoxins in fish feed:

– Affect the health of fish leading to

• mortalities, poor growth, suppressed immune response, lesions

– Can accumulate in fish tissue

• posing a risk to human health

– Leads to losses in production i.e.

• Fish - poor feed conversion, mortalities, rejection at market
• Feed - rejection at market, waste due to disposal

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Justification

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• Nyeri County , ≈ 150 km North of Nairobi.
• 5 sub-counties:

– Othaya; Kieni East; Kieni West; Nyeri Central and Tetu.

• Total population: 693,558 (2009 census)
• Altitude: 3,076 - 5,199 m above sea level
• Annual rainfall: 1,200mm-1,600mm (April - May) and

500mm-1,500mm (Oct to Dec)

• Tilapia, Rainbow trout and catfish all reared

Study area

• Study design: cross sectional
• Snowball technique - used to identify and enroll fish farmers into the

study.

• Semi-structured questionnaire - used to collect data on knowledge,

attitudes and practices associated with alfatoxin in fish feed.

• Fish feed samples were collected from the farms visited
• Feed analysis - total aflatoxin levels by ELISA
• other mycotoxins by LC-MS

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Study design

• A total of 209 fish farmers were visited and questionnaires administered.
• Of those, only 60 (28.7%) were in possession of fish feed at the time of visit.

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Results and Discussion

Sub county Questionnaires administered Samples collected % (n) % (n) Kieni East 24.9 (52) 20.0 (12) Kieni West 15.3 (32) 16.7 (10) Nyeri Central 15.8 (33) 15.0 (9) Othaya 20.1 (42) 11.7 (7) T etu 23.9 (50) 36.7 (22) T

• tal

100.0 (209) 100.0 (60)

• All samples had aflatoxins

detected

• Total Aflatoxin levels

range: 0.53 - 39.65 ppb. average: 7.74 ± 1.19 ppb median: 3.96

• Samples above limit:

10ppb: 14 (22.2%)

20ppb: 4 (6.7%)

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Aflatoxin prevalence

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T

• tal Aflatoxin level (ppb)

Type of feed % (n) Mean Median Min Max Commercial feed 28.6 (17) 7.56 4.30 1.27 39.65 Homemade feed 46.0% (28) 8.49 3.96 0.53 31.21 Ingredient 25.5 (15) 6.55 3.16 0.87 32.77 T

• tal

100.0 (60) 7.74 3.96 0.53 39.65 Ingredients % Maize bran 25% Wheat bran 25% Pollard 25% Cotton 5.6% Silver cyprinid 5.6%

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Other mycotoxins identified

• 18 mycotoxins identified
• 95% of samples had >1 mycotoxins
• 20% of samples had 6 mycotoxins

Mycotoxin % (n) Deoxynivalenol (DON) 60.0 (24) Aflatoxin B1 and G1 45.0 (18) Fumonisin B1 and B2 50.0 (20) Zearalenone (ZON) 17.5 (7) T

• 2

10.0 (4)

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Post mortem examination

• Aflatoxins affects the liver causing tumorous lesions
• Aflatoxins cause immuno-suppression leading to increased susceptibility to other

conditions caused by bacteria, parasites or viruses

Tumorous lesions on the liver Hemorrhages on the muscle Hemorrhagic intestinal content

• Clinical history

– Fish deaths (58.2%), poor growth rates (47%), decreased feeding (10.5%) and tumours (3.5%) – Aflatoxicosis is associated with high mortalities, poor growth rates and tumours

• Feeding practices

– Commercial fish feed: 34.8% - exclusively; 45.9% - mixed with other types of feed – Ingredients for homemade feed and supplements: Maize bran (62.1%) , Wheat bran (59.8%) , Pollard (34.5%), Silver cyprinid (21.8%), Cottonseed cake (19.5%) – Aflatoxins have been identified in mostly in maize, cotton seed and groundnuts in Africa.

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Survey findings

• Many respondents had good knowledge on aflatoxins:

– 90.1% had heard of aflatoxins – knew moisture (61.7%) and poor feed storage (25.3%) led to mould growth and alfatoxin production – 83.2% thought moldy feed affected fish health – 72.5% would throw away all mold feed and not give to fish. – 82.5% felt it was unacceptable to give moldy feed to fish – 59.8% would use/keep fish feed for ≈3.6 ± 0.3 months before considering it unfit for fish

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Knowledge and Attitude

• Many respondents reported good practices associated with alfatoxin occurrence.

– Always checking feed manufacturing dates (41.4%) before purchase – Always checking feed expiry dates (42.5%) before purchase – Storing feed indoors 86% while packaged in sealed, lined polythene bags – checking feed before feeding (71.4%) – Selecting feed with the oldest manufacturing date (40.6%) or earliest purchased (32.1%)

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Practices

• Mycotoxins were prevelent in the fish feed:

– Total Alfaltoxin - 22.2% (1 in every 5 feed) – Deoxynivalenol (DON) – 60% (3 in every 5 feed) – Fumonisin B1 (FUMB1) - 32.5% (≈2 in every 5 feed) – Fumonisin B2 (FUMB2) - 17.5% (≈ 1 in every 5 feed) – Zearalenone (ZON) – 17.5% (≈ 1 in every 5 feed)

• Fish exposure to these mycotoxins may lead to adverse health effects and death
• Additional mitigation strategies need to be employed to reduce the number and levels of

mycotoxins present in the feed

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Conclusions and Recommendations

• Maize and wheat byproducts are the main ingredients used for making the feed

– High levels of aflatoxins have been isolated in maize in Africa and Kenya – Sources of maize bran need to be clean and storage needs to be improved

• Many respondents knew of mold and aflatoxins and reported good practices in handling and

storage of fish feed – Poor storage and handling of feed lead to fungal growth and subsequesnt mycotoxin production – Although knowledge and good practive was reported, more information/training is still needed to reduce occurence in feed and exposure to fish

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Conclusions and Recommendations

• God – health and strength
• NORAD – funding through TRAHESA project
• NMBU, Norwegian veterinary institute and UoN - facilities
• Profs. Jan, Mbuthia and Mutoloki; Drs. Gunnar, Maina, Gathumbi – guidance
• Drs. Waruiru, Njagi, Mulei, Karina - field and logistics assistance
• Nyeri CDVS, DVO, fisheries department – authorization and facilitation
• Fisheries officers and laboratory technicians – field and laboratory assistance
• Nyeri fish farmers – data and samples
• Family - support

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Acknowledgements