AFLATOXIN IN LIVESTOCK VALUE CHAINS

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1 AFLATOXIN IN LIVESTOCK VALUE CHAINS ERASTUS K. KANG ETHE, DEPARTMENT OF PUBLIC HEALTH PHARMACOLOGY AND TOXICOLOGY, UNIVERITY OF NAIROBI.

2 OVERVIEW Introduction Livestock production systems and population Sources of aflatoxin in Livestock Aflatoxin in feeds and milk Impact of aflatoxin in livestock Impact of aflatoxin in humans Economic impact Control of aflatoxin in livestock value chain 2

3 INTRODUCTION Mycotoxins are secondary metabolites produced by colonizing fungi. Fungi are eukaryotic, single celled, multinucleated organisms. About 70,000 species of fungi have been described but it is estimated that over 1.5M species exists. The colonizing fungi can live on substrates as parasites, symbionts or saprophytes. 3

4 INTRODUCTION They colonize by secreting enzymes that help break down complex matrices. In the process they secrete low molecular weight compounds with toxic properties called mycotoxins. Dispute as to why fungi produce the mycotoxins anti- insect and anti rodent agents while others think are reactions to agricultural biocides. 4

5 INTRODUCTION Between 300 and 400 different mycotoxins are known today, but not all of them are present in higher concentrations or have a significant health or economic impact Aflatoxin, one of the mycotoxins is produced by fungal species of the genus Aspergillus with Aspergillus flavus and A. parasiticus the key toxin producers 5

6 INTRODUCTION Aspergillus fungus is widely spread in nature and can be found in kernels of corn, wheat, sorghum, barley, oats, rice, cotton seed, coffee, peanuts and many other crops such as cassava, yam, soybeans and dry fish Aspergillus exists as toxigenic and atoxigenic strains The toxigenic fungi can invade crops during preharvest and post harvest periods producing toxins. Toxin production is favored by environmental conditions - temperature, moisture, water activity, relative humidity 6

7 INTRODUCTION Growth of A. flavus and A. parasiticus Temp = C (range 6 54 C) aw = 0.95 (range ) Aflatoxin production by A. flavus and A. parasiticus Temp = C aw = ( ) 7

8 MYCOTOXIN WORLD WIDE DISTRIBUTION Distribution (Continent) Toxin Africa and Asian Sub continent Australia North America South America Eastern Europe Western Europe Aflatoxin Aflatoxin and Fumonisin Aflatoxin, Ochratoxin, Zearalenone (ZEN) and Deoxynivalenol (DON) Aflatoxin, Fumonisins, Ochratoxin ZEN, DON, ZEN and DON Ochratoxin, ZEN and DON 8

9 Fungal Spps, Major Toxin and Crops affected Fungal Species Mycotoxins Crops mainly attacked Aspergillus spp Aflatoxins, Maize, sorghum, millets, groundnuts, rice, wheat all grains Fusarium spp Fumonisins, Zearelonone, Deoxynivalenol (T1 and T2), Maize, sorghums and millets Maize Cereals (maize, wheat etc) Aspergillus and Penicillium spp Ochratoxins Coffee and Cocoa 9

10 SOURCES OF AFLATOXIN FOR LIVESTOCK Growing pasture fungal contamination of grasses Hay, straw and Maize stovers Silage Commercial Feeds [ as a result of 25% of the worlds cereals are contaminated by aflatoxins (FAO, 1987, CAST 1989)] Increase in importance as source 10

11 LIVESTOCK PRODUCTION SYSTEMS 11

12 Distribution of Dairy cattle in Kenya Tanzania, majority of livestock found in the lake and southern highlands and central regions, dairy herd at 2011 was 0.03% of the cattle population.. (MoLD 2011) Rwanda mainly in Byumba 15%, Kibungo 19% and Ruhengeri 10% ( Butera and Rutangwenda 2004) In Uganda dairy is concentrated in the south western 32%, Central, 29%, Eastern 23%, northern 18%. (EADD Report 2008) 12

13 LIVESTOCK PRODUCTION SYSTEM AND AFLATOXIN Production system influences aflatoxin levels in the animal source foods Livestock only rangeland bases systems have less contaminated ASF compared to MRA/MRH/MRT systems (Intensive livestock) Kiambu farmers spent five times more money on animal feeds than Nyandarua dairy farmers 13

14 Livestock and cattle feed 14

15 Aflatoxin in maize and groundnuts Livestock feeds are mainly cereal based. These cereals (maize, groundnuts,wheat) are easily contaminated with aflatoxin. Maize contamination with aflatoxin has been shown to be a high as 46,000ppb (Lewis et al 2005) and in Uganda between ppb (Kaaya 2005) Groundnuts are other major feed ingredients and these have also been found to be contaminated with aflatoxin ranging from 2688 and 7525 ug/kg in Busia and Homabay, Kenya (Mutegi, 2009), and in Uganda ranges between 23-80ppb have been reported, Kaaya (2006) 15

16 Aflatoxin in maize and groundnuts In 2012 in Tanzania, the areas of greater risk of aflatoxin contamination of maize is eastern region with maize contamination level of 43% and groundnuts are northern, southern and eastern at 20 % (TFDA Country Status Report 2012) 16

17 Livestock and Aflatoxin As intensification increases there is heavy reliance on commercial feeds/ unwholesome grains, this will raise the risk of feeding contaminated feeds with aflatoxin Ways of utilizing spoilt maize 17

18 Aflatoxin in Feeds in urban and Peri-urban Kang ethe and Lang at 2009 Sources of Feed % positive for Total Aflatoxin % > 10 ppb Total Aflatoxin Smallholder farmers (n=412) 85 (353/412) 38 (155/412) Feed manufacturers (n= 243) 81 (197/213) 25 (60/243) Agrovets (n=175) 87 (153/175) 26 (43/175) 18

19 Aflatoxin in animal feeds from rural areas Levels of aflatoxins Division Source Negative Less than 5 ppb Greater than 5 ppb Total Kipkarren Farm (n=108) Market (n=1) Kilibwoni Farm (n=36) Market(n=3) Kaptumo Farm (n=57) Market (n=2) Makindu Central Market (n=2) Feed Total (209)

20 Consequence of Aflatoxin in Animal Feeds Aflatoxin found in eggs The ratio of transmission of aflatoxin B1 in feed to eggs and muscle has been shown to be 5000:1 (Oliveira et al 2000, Bintvihok et al 2002) No data on prevalence of aflatoxin in Poultry and eggs and Pork in Kenya or East Africa. 20

21 Aflatoxin in milk from urban and peri-urban areas Sources of milk % positive AFM1 % > 50ppt Urban smallholder dairy farmers (n= 439) 72 (315/439) 14 (63/439) Large/medium farmers (n=85) 83 (71/85) 46 (39/85) Processed marketed liquid Milk (n= 89) 98 (88/89) 30 (27/89) 21

22 Aflatoxin in Milk Rural (semi intensive systems) 22

23 Aflatoxin in milk In Tanzania, 34 out 37 randomly picked milk samples were contaminated with afltoxin M1 with levels ranging from 0.005ug/kg to 0.855ug/kg ( Urio, et al 2006) 23

24 Impact of aflatoxin in Livestock Sensitivity to aflatoxin varies with livestock species. Poultry and dogs being most sensitive and suffers from acute toxicosis 1960, 1977, 1984/85; 2002 in Kenya Ruminants are not very susceptible. Rumen flora makes substantial changes in the aflatoxin decontamination. Only a third of the amount in the feed is detected in milk. 24

25 Farmers perception of the impacts of feeding mouldy grains to Livestock Risks to livestock n Kaiti (%) Wote (%) Division Makindu Central (%) Kipkaren (%) Kilibwoni (%) Kaptumo (%) Reduce milk production Reduce milk quality Reduce weight gain Susceptible to diseases Death Loss of appetite Liver problems Others Total 25

26 Impact of Aflatoxin in Cattle Clinical signs seen in cattle fed contaminated feeds - chronic exposure Target organ is the Liver Reduced weight gain Reduced feed conversion efficiency Reduced milk production (33 % Masri et al 1969) Decreased feed intake Reduced fertility (2%, Gutherie 1979) Increased susceptibility to diseases 26

27 Impact of aflatoxin in Poultry Poultry are the most susceptible to aflatoxin among the livestock with ducks being the most among poultry. Clinical signs include:- Reduced feed intake Reduced egg production Reduced hatchability of eggs Poor egg shell quality Leg problems rickets Broiler, increased risk of bruising 27

28 Impact of aflatoxin in Pigs Feeding system in pigs can increase incidences of introduction of aflatoxins- wet feeding systems Clinical signs in piggery include:- Reduced feed intake Reduced growth rate Lower sow productivity 800ppb fewer piglets born live /weaned Liver damage Vit E (mulberry heart disease) and A deficiency (incoordination and hind legs paralysis) 28

29 Impact of Aflatoxin in Humans Acute toxicity Loss of life Chronic exposure Carcinogenic (hepatocellular carcinomas) Immunosuppresion increased susceptibility to infections Teratogenic effects malformations/ lack of essential enzymes Growth stunting, wasting, malnourishment and cognitive development impairment 29

30 Economic losses Bearer of the cost Farmer Consumer of livestock products National Government Economic loss Reduced profitability increased treatment costs Increased feeding costs High consumer prices Increased treatment costs due to impaired health Low productive capacity Reduction in foreign exchange Loss of markets Increased human and livestock medical bill Increased costs of surveillance Increased costs of training,extension and communication programmes 30

31 Aflatoxin control a One Health Issue Environment: extreme drought, moisture, heat, compromised plants Fungal growth / aflatoxin production Contamination of human & animal food Human consumption Breast milk In utero Infants Milk eggs Animal consumptio n 31

32 Control of Aflatoxin in livestock Livestock exposure is mainly from contaminated feeds. Control strategies should target prevention of contamination of animal feeds. Promoting public awareness on the role of livestock as source for human exposure Knowledge of the safety of milk from cattle fed on mouldy maize 32

33 Control of Aflatoxin in livestock Strategies adopted for prevention of contamination in crops will definitely reduce the chances of the feed being contaminated Pre and post harvest methods Manufacturers of animal feeds, stockists to maintain conditions at storage and transportation of feeds and raw materials that do not favor fungal growth and toxin production 40% stored on the raised flat form, of these 80% were positive while those who stored feed on the floor 60% were positive 33

34 Control of aflatoxins in Livestock Risk of contamination at the farm is O R= 0.2 Self regulation by Feed industry with penalties for non compliance Cereal millers need capacity building (human resource and laboratory personnel) to enable self regulation to be effective Many millers outside the cereal millers (30%) association and AKEFEMA (50%) 34

35 Control of Aflatoxin in livestock Regulations Currently in the EAC the regulations for animal feeds is 20ppb for Total Aflatoxin and 10ppb for AFB1 ( EU 4ppb in feeds and 50ppt in milk USDA 500ppt for milk). How stricter do we need to be? Will this increase compliance? Central government to institute regular monitoring and surveillance of animal feeds and products On going but needs more effective TCP NFSCC 35

36 Control of Aflatoxin in livestock Use of novel technologies to prevent absorption in the intestines NovaSil (binders) 69% of feed manufacturers were using adsorbents in dog and chicken feeds (Kang ethe and Lang at 2007) Alternative uses of contaminated grains to prevent them getting into animal feed chain and hence human exposure 36

37 Control of Aflatoxin in Livestock Testing is a challenge as the cost is high, dependence on commercial high cost expensive kits and few laboratories with the capacity. This mitigates the demand for testing. Need cost effective rapid test kits that are available and affordable No data exists on other livestock species value chains than livestock poultry, pigs, fish. 37

38 THANK YOU The true essence of life is to plant a tree, under whose shade, you do not expect to sit 38