A field survey was carried out to assess the nature and extent of contamination of groundnut seeds and cakes, and some other selected food crops (Cajanus cajana, Sorghum and Sesame) with aflatoxin B1. The survey results revealed that groundnut seeds contained significantly (P<0.01) the highest level of aflatoxin among the seeds of the selected food crops. Moreover, many factors were found to effect significantly the incidence of aflatoxin contamination in groundnut cake, such as type of soil, method of harvesting of the crop, method of oil extraction, storage period and the type of store. The groundnut cultivated in clay soil seemed to contain significantly (P<0.01) higher aflatoxin content than that grown in sandy or silt soil. On the other hand, the method of crop harvesting had no significant effect on aflatoxin content of groundnut cake. The aflatoxin content was significantly increased (P<0.01) by increasing the storage period, and the groundnut cake stored in modern concrete roof and floor stores contained significantly (P<0.01) lower aflatoxin compared with the cake stored in traditional mud building stores. Moreover, the mechanically pressed cakes contained significantly (P<0.05) lower aflatoxin than the cakes pressed traditionally.
Two experiments were conducted to determine the effect of aflatoxin ingestion, from naturally contaminated groundnut meal on the productive performance of broiler chicks and laying hens.
The experiments were in the form of a six-weeks broiler trial and a ten-weeks laying trial. Both trials were arranged in a randomized block design, with four blocks and eight pens within the block in each trial giving four replicates of each of eight experimental diets in each trial.
In the broiler trial, 308 day-old broiler chicks, were distributed randomly in 4 blocks of eight pens, each at the rate of eight chicks per pen. Feed and water were provided ad libitum. Eight experimental diets were formulated, using naturally aflatoxin contaminated groundnut cake, to give different levels of dietary aflatoxin, namely 2.5, 5, 7.5, 10, 12.5, 15, 17.5, and 20 ppm. The broiler trial revealed a significant reduction in feed consumption on and above the diet containing 15 ppm or more aflatoxin (P<0.01). The weekly mean body weight on and above the diets containing 10ppm were significantly (P<0.01) reduced. The peak mortality rate occured on the diets containing 17.5 and 20 ppm aflatoxin. Levels of liver enzymes, albumin, total protein, and Calcium in the blood were significantly decreased with the increase of aflatoxin in the diet (P<0.01), while the serum uric acid and urea levels were significantly increased (P<0.01).
The carcass parameters (cold carcass and hot carcass weight) were significantly decreased (P<0.01) as the levels of aflatoxin B1were increased, in the diets, while the shrinkage percent was significantly increased.
In the laying trials, 160 Bovan hybrid laying strains 36 weeks of age, were distributed randomly to 4 blocks (rows of cages), each block consisted of 8 cages, and each cage contained 5 birds. Eight experimental diets were formulated, using naturally contaminated groundnut cake, to contain (5, 10, 15, 20, 25, 30, 35 and 40 ppm) of dietary aflatoxin. Mean productive parameters, namely daily feed intake, hen-day egg production, egg weight and egg shell thickness were significantly decreased (P<0.01) by increasing the aflatoxin level in the diets. The effect of aflatoxin B1 on these parameters started to have an effect from the fourth week onwards. Similarly, the albumen height was decreased significantly (P<0.01) with increasing the level of aflatoxin B1 in the diets, and the effect started to show up from the third week onwards.