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Survey conducted to investigate recurrent outbreaks of diseases in poultry farms revealed that broiler/layer feeds and their ingredients were frequently contaminated with aflatoxins. During 1979-1985, a total number of 3741 samples were analysed. Analysis of 1161 samples of feed ingredients like wheat, wheat bran, broken rice, sela rice (Parboiled), rice polish, rice protein concentgrate, sorghum, corn, corn gluten feed and corn gluten meal showed 36.08% samples were aflatoxin contaminated, contamination ranging from 2-1500μg/kg, with an average AFB1 content of 88.35 ppb. One hundred and ninety five samples had aflatoxin content less than 20 ppb, 102 between 21-100 μg/kg, 97 over 100 ppb but below 500 ppb, and 23 of the positive samples between 501-1000 μg/kg. Only 2 samples contained 1245 and 1500 ppb of AFB1 Use of cottonseed meal as an ingredient in poultry feed is quite extensive, 70.9% cottonseed meal samples were positive for aflatoxin with an average of 155.7 μg/kg, and ranged between 2-1629 μg/kg, Forty three percent positive samples of sunflower meal, and 29.34% of repeaseed meal had aflatoxin 2-1709 μg/kg, and 4-547 μg/kg, respectively. About 18.37, 38.77 and 212.4% samples fo soybean meal, sesame cake and safflower meal respectively were aflatoxin positive. Out of one hundred and eithty samples of fish meal, 38 of meat meal and 67 of blood meal were respectively 22.9, 5.26 and 5.97% aflatoxin positive with an average content of 49.11 and 27.77 μg/kg. Guar meal and matri (Lathyrus aphaca), the two main pluses commonly used in poultry feed, respectively had 14.23 and 18.9% aflatoxin positive samples. The average content being 54 and 48.15 μg/kg, respectively Out of 283 (76.28%) positive samples of broiler starter feed, 120 contained AFB1 less than 20 ppb, 124 betweer 21-100 μg/kg, whereas 33 samples had more than 100 ppb 72.72% broiler finisher feed samples were found contaminated, with an average AFB1 content of 18.65 μg/kg, and a range between 1-353 μg/kg, In layer feed (chick starter, grower/prelay and layer mash), 416 samples (72.85%) were aflatoxin positive, the range being 1-659 μg/kg, with an average aflatoxin content 64.96 ppb Visits to the poultry farms revealed that repeated outbreaks of diseases in broiler/layer operations were creating a setback in poultry industry. In most of the cases, broiler chicken showed reduced weight gain, pale comb and bruising. In sever cases their bellies were filled with slimy fluids. On autopsy an edematous viscera, enlarged pale lover with lesions, enlarged kidneys and spleen, and sometimes hydro pericardium was seen. In such cases mortality was also quite high In layer, a marked decrease in egg production, sometimes 95% to 60% was observed. On autopsy, the affected hens showed shriveled ovaries and pale livers with lesions. The broiler/layer feed, on analysis, at times showed presence of aflatoxin between 259-659 μg/kg, of feed. The changeover from aflatoxin contaminated to aflatoxin free feed always improved the condition of affected birds, implicating that the levels of aflatoxin in the feed coupled with bad management were the two main causes of frequent outbreaks of aflatoxicosis It was observed that the day old checks, supplied by different commercial hatcheries, were not of uniform size and weight. The smaller and weaker chicks never attained the same weight as others. The presence of such in large number also resulted in economic losses. To investigate the causes for smaller and weaker chicks with leg problems, two experiments of chick embryo bioassay were conducted. In the first experiment 0.025 ppb AFB1, injected in fertile eggs of four layer breeds namely Fayomi “F” Layalpur Single Breed “LSB” Doki “D” and mini Rhode Island Red “RIR” respectively gave 45, 30, 25 and 15% hatch, thus showing different genetic susceptibility. In the treated groups the nonsurviving embryos were malformed. The chicks of the treated brood were mostly weaker, some had leg problems, drooping wings and had a mean weight of 32.7 gm as against 38.1 gm for control chicks. The weight gain in control brood after 8 weeks in “F” “LSB” “D” and “RIR” was 423, 451, 423, and 388 whereas in treated it was 437, 354, 305 and 252 gm respectively. In the second experiment on chick (single comb white leghorn) embryo bioassay, it was observed that the hatch was dose dependent. The higher AFB1 dose of 0.081 ppb/egg resulted in 87% underdeveloped embryo which died in the shell by the 12th day of incubation. The highest toxin dose, 0.216 ppb/egg, killed 93% of the embryos by the 5th day of development, and there was 100% mortality by the 9th day. These embryo bioassay experiments indicate that aflatoxin in the feed of breeding stock could result in poor hatch and handicapped chicks, depending on the amount of aflatoxin ingested. The results of the two chick embryo bioassay also suggest that weak and small size ckicks connot attain the same weight in the stipulated time. The four layer breeds showed different susceptibility to aflatoxin Different in su sceptability were also noted in broiler chicks. In an experiment, 3 strains (A, B and C) of day old chicks were fed with an aflatoxin contaminated (250 μg/kg,) feed, for 3 weeks. On compairing the treated groups with control, it was observed that growth depression due to aflatoxin in A and C was more than in strain “B”. this variation in response, is indicative of the fact that genetic differences do exist and careful selection of broiler strains could help in minimizing the problems of aflatoxicosis in poultry In the same broiler experiment, other parameters were also studied. It was observed that at the end of first week, the liver weight in all the treated chicks was less than the controls. However, by the end of second week it started increasing. There was a marked increase in liver weight of all the 3 weeks old treated chicks in all the strains. Hemoglobin content of all the treated chicks showed a decrease which became alarming by the end of second week, however, by the end of 3rd week it improved. There was a drastic reduction of serum proteins in all the chicks ingesting aflatoxin. The protein levels improved by the 3rd week in treated chicks. It was interesting to not that serum lipids increased slightly in treated chicks in the first week, but decreased to a great extent in the second week, and this persisted in the third week also. The serum bilirubin showed slight increase by the end of third week In conclusion, it can be said that observations and findings. Reported here, are in line with many of the researches published earlier. Presence of such levels of aflatoxin, in commercial feeds, possibly, is one of the contributory factors for diseases in chicken; and under poor management, sever outbreaks result in high mortality and great economic loss to the farmers. In many such disease outbreaks, feed consumed at the farms, on analysis, invariably showed aflatoxin contamination, and the pathological features were similar to those described for aflatoxicosis by earlier investigators. The factors which promote elaboration of aflatoxins in the poultry feed ingredients were, inadequate pre and post harvest conditions, untimely rains, floods, drought, lack of facilities for quick drying of the harvest, insect attack and poor storage conditions. Besides, poultry-feed-mill-owners use feed ingredients of inferior quality for more profit. It is suggested that improvement in agricultural practices, and selection of suitable genotype resistant to fungal invasion and aflatoxin production, would be a positive step. Selection of broiler/layer, breeds and strains, resistant to aflatoxicosis, would help in minimizing the problem. There should be strict regulations for aflatoxin limits in the poultry feed. Pakistan is a sub tropical developing country, where weather conditions are most uncertain, contamination of one or several commodities is inevitable. Detoxification, therefore, seems to be one of the remedies for combating aflatoxins in poultry feed

Item Type:Thesis (PhD)
Subjects:Biological & Medical Sciences (c) > Biological Sciences(c1) > Biology (c13)
ID Code:1222
Deposited By:Mr. Muhammad Asif
Deposited On:04 Jan 2007
Last Modified:04 Oct 2007 21:05

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