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76 Aflatoxin levels in feeds and feed ingredients...

Received - 02.06.13Accepted - 01.10.13

Abstract

Total aflatoxin and aflatoxin B1 levels infeeds and feed ingredients of livestock andpoultry in Kerala were analysed in 709 samplesby fluorometry after extraction using specificmonoclonal antibody based immune-affinitycolumns. The levels of total aflatoxin varied widelyfrom 1 to 400 ppb in feeds and levels were foundto be higher in poultry, duck and quail feeds whencompared to their accepted dietary limits. Eventhough the levels of total aflatoxin varied from1 to 680 ppb among different feed ingredients,the mean levels were found to be very high inmaize (122 ± 53.36 ppb) and ground nut cake(139.75 ± 31.1 ppb). Aflatoxin B1 contributed to66 to 82% of total aflatoxins in the feed. Totalaflatoxin levels were found to be very high duringthe months of October and November (North-east monsoon season).

Keywords:- Aflatoxin, aflatoxin B1, livestockfeed, feed ingredients

Aflatoxins are a closely related het-erocyclic group of toxic secondary metabolitesof certain strains of fungi, chiefly Aspergillusflavus and A. parasiticus. Since warm and hu-mid climatic conditions favour aflatoxin produc-tion, contamination of feed grains and oil cakeswith aflatoxin are more common in tropicalcountries. Aflatoxins produce most severe andchronic problems in agriculture, livestock,poultry and human beings. They are associ-ated with low productivity, immunosuppres-sion, liver and renal damages, carcinogenicand teratogenic effects. Derivatives of aflatox-ins are found in milk, egg, meat and their prod-ucts which point to its public health impor-tance. This study was undertaken to estimate

AFLATOXIN LEVELS IN FEEDS AND FEEDINGREDIENTS OF LIVESTOCK ANDPOULTRY IN KERALA

B. Bibin Becha1 and S.S. Devi2

Avian Disease Diagnostic Laboratory,Manjadi, P.O., Thiruvalla, Kerala – 689 105

1. Assistant Professor, Dept. of Animal Reproduction, Gynaecology and Obstretics, CVAS, Mannuthy2. Veterinary Surgeon, Regional Animal Husbandry Centre, Thiruvananthapuram

the level of aflatoxin contamination in livestockand poultry feeds and feed ingredients inKerala during various seasons.

Materials and Methods

A total of 709 samples of feed andfeed ingredients were collected from differentlivestock and poultry farms of Kerala.Aflatoxins were extracted by blending 50 g offeed sample with salt and 100 ml solution ofmethanol and distilled water (80:20). Thefiltered extract is diluted (1:4) using distilledwater and filtered again through glass fibrefilter paper. From 10 ml of the filtrate, aflatoxinswere adsorbed onto a monoclonal antibodybased immunoaffinity column by passing itthrough the column at the rate of two drops/sec. Aflatoxins were eluted out into a cuvetteusing one millilitre of HPLC grade methanol.This elute was derivatized with one millilitre ofdeveloper solution and the levels of aflatoxinswere estimated quantitatively using acalibrated fluorometer (Cigic and Prosen,2009). Levels of aflatoxin B1 was alsoestimated in 17 samples collected at randomby the same procedure using immunospecificcolumns for Aflatoxin B1. The mean levels oftotal aflatoxin, aflatoxin B1 and proportion ofaflatoxin B1 in different feeds and feedingredients were also analysed. Seasonalvariations influencing level of total aflatoxin infeeds were also analysed.

Results and Discussion

The levels of aflatoxin in differentfeeds and feed ingredients are summarised inTable 1 and 2. The levels of aflatoxin variedwidely in all types of feeds from 1 to 400 ppb.The mean level of aflatoxin was found to behigher in poultry, duck and quail feeds

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compared to their acceptable dietary limits asper the recommendations of package ofpractices. Acceptable limit of aflatoxin in feedof poultry is 20 ppb and that of duck is 10ppb. The levels of aflatoxin varied widely in alltypes of feed ingredients from 1 to 680 ppb.The mean level of aflatoxin was found to bevery high in maize (122 ± 53.36 ppb) andground nut cake (139.75 ± 31.1 ppb). However,these levels are lower than the levels of totalaflatoxin recorded in poultry feeds and feedingredients by Khan (1994).

The levels total aflatoxin and aflatoxinB1 in different feeds are summarised in Table3. Aflatoxin B1 contributed 66 to 82 per centof total aflatoxins present in the feed.

Levels of total aflatoxin in feeds andfeed ingredients during different season of theyear were analysed and the results aresummarised in Table.4. Among the 709samples tested during the different season ofthe year, total aflatoxin levels were found tobe very high during the north-east monsoonseason (October and November). Storage ofcereals in warm and humid conditions in-creases the aflatoxin contamination(Saleemullah et al., 2006). Giridhar andKrishnamurthy (1977) found that 25.7 per centof commercial ground nut oil contained morethan 100 ppb aflatoxin and higher toxin con-centration was found in oil extracted fromkharif (rainy) season crop.

It is practically difficult to producefeeds and feed ingredients free from aflatoxin.But the very high levels of aflatoxin in maizeand ground nut cake warrants to limit their usein feed to minimum required levels and onlyafter proper testing for its levels. Reddy et al.,

(2009) reported that only two per cent of therice samples collected from different states ofIndia showed aflatoxin B1 contamination abovethe permissible limits. Jowar and broken ricecould be used to replace maize as energysupplements in feed, since these ingredientswere found to contain only permissible levelsof toxin. Aflatoxin B1 contributes to the majorportion of total aflatoxin in feed. Bhat et al.,(1996 and 1997) showed that aflatoxin B1

levels exceeded the permissible Indianregulatory limit of 30 ppb in 21 per cent ofground nut samples and 26 per cent of maizesamples collected from 11 different states.Since aflatoxin B1 is the most toxic aflatoxin,its level has to be considered along with totalaflatoxin before accepting or choosing a feedor feed ingredient for dietary use in animals.

References

Bhat, R.V., Vasanthi, S., Sashidhar Rao, B.,Nageswara Rao, R., Sudershan Rao,V., Nagaraja, K.V., Girija Bai, R.,Krishna Prasad, C.A., Vanchinathan,S., Roy, R., Saha, S., Mukherjee, A.,Ghosh, P.K., Toteja, G.S., Saxena,B.N. 1996. Aflatoxin B1 contaminationin groundnut samples collected fromdifferent geographical regions ofIndia: a multicentre study. Food Addit.Contam. 13: 325–331

Bhat, R.V., Vasanthi, S., Sashidhar Rao, B.,Nageswara Rao, R., Sudershan Rao,V., Nagaraja, K.V., Girija Bai, R.,Krishna Prasad, C.A., Vanchinathan,S., Roy, R., Saha, S., Mukherjee, A.,Ghosh, P.K., Toteja, G.S., Saxena,B.N. 1997. Aflatoxin B1 contaminationin maize samples collected from

Table 1. Levels of aflatoxin in different feeds

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different geographical regions of India– a multicentre study. Food Addit.Contam. 14: 151–156.

Cigic, I. K. and Prosen, H. 2009. An overviewof conventional and emerginganalytical methods for determinationof mycotoxins. Int. J. Mol. Sci.,10: 62 – 115.

Giridhar, N., Krishnamurthy, G.V. 1977.Studies on aflatoxin content ofgroundnut oil in Andhra Pradesh withreference to climatic conditions andseasonal variations. J. Food Sci.Technol. 14: 84–85

Khan, B. A. 1994. Aflatoxin contamination ofPoultry feed and resulting disordersin chicken. Thesis . University ofKarachi, Pakistan.

Reddy, K.R.N., Reddy, C.S. and Muralidharan,K. 2009. Detection of Aspergillus spp.and aflatoxin B1 in rice in India. FoodMicrobiol. 26: 27–31.

Saleemullah, Iqbal, A., Khalil, I.A and Shah,H. 2006. Aflatoxin content of storedand artificially inoculated cereals andnuts. Food Chem. 98: 699 – 703.

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Table 4. Levels of total aflatoxin in feeds during different season

Table 2. Levels of aflatoxin in different feed ingredients

Table 3. Levels of total aflatoxin and aflatoxin B1 in different feeds