Sampling plans for the determination of aflatoxin B1 in large shipments of animal feedstuffs.

Incremental samples (50, 100, and 500 g) were systematically collected from large shipments of copra meal pellets, copra cake, and palm kernel cake to study the distribution of aflatoxin B1 and evaluate adherence of distribution to the model, CV(2)is (EQ) = A + B/Mis (where CVis = coefficient of variation of the true concentration of aflatoxin B1 within the incremental samples; Mis = mass of the incremental samples; and A and B are constants). Also evaluated was the distribution of aflatoxin B1 among 1 kg composite samples, produced both by random combination of existing incremental samples and by collection of 1 kg composite samples (composed of 10 x 100 g increments) from additional batches of copra meal pellets and cottonseed cake. The efficiency of selected sample preparation (grinding and subdivision) procedures was compared, culminating in the development and description of a variety of sampling plans. The coefficient of variation (CV) among incremental samples varied from 0 to 38%, and was independent of incremental sample size. No significant difference (F-test, 5% significance level) was found between the efficacy of 4 sample preparation methods when these methods were applied to the commodities described above. Various sampling plans were evaluated with estimated CVs from 4.0 to 12.5%, for the aflatoxin B1 content of the composite samples.

Evaluation of sampling plans used in the United States, United Kingdom, and The Netherlands to test raw shelled peanuts for aflatoxin.

The United States is a large producer and exporter of peanuts. The United Kingdom and The Netherlands are major importers of U.S. peanuts. Each country has a different guideline or legal limit for peanut products containing aflatoxin. Peanuts are tested for aflatoxin in each country by using specifically designed aflatoxin sampling plans to determine if the aflatoxin concentration in a lot of raw shelled peanuts is less than the guideline or legal limit. For raw shelled peanuts, the U.S. plan has the highest sample acceptance limit of 15 ng total aflatoxin/g, the UK plan has a sample acceptance limit of 10 ng total aflatoxin/g, and the Dutch Code of Practice (called the Dutch plan) has the lowest sample acceptance limit at 3 ng aflatoxin B1/g. The U.S. plan uses a maximum of 3 sampling units, each weighing 21.8 kg; the UK plan uses a single sampling unit of 10 kg; and the Dutch plan uses 4 sampling units, each weighing 7.5 kg. The sampling variance is lowest for the U.S. plan and highest for the Dutch plan. The sample preparation variance is lowest for both the Dutch and UK plans and highest for the U.S. plan, primarily because of the mill type used to comminute the kernels in the sample. For a given distribution among lot concentrations, the U.S. plan accepts the greatest number of lots and the Dutch plan rejects the greatest number of lots. The average aflatoxin concentration among accepted lots is highest for the U.S. plan and lowest for the Dutch plan.(ABSTRACT TRUNCATED AT 250 WORDS)

Design of sampling plans for mycotoxins in foods and feeds.

The control of the occurrence of mycotoxins in foods and feeds requires effective surveillance and quality control procedures which facilitate the identification and control of the mycotoxin problem respectively. Surveillance and quality control procedures involve a sequence of sampling, sample preparation, and analysis steps; and the integrity of the data produced by these procedures will be determined by the effectiveness of these steps. It is imperative that the sampling step is performed as accurately as possible so that the sample collected is representative of the batch of food or feed under investigation. Needless to say, the collection of a biased sample will completely invalidate the resultant analytical data. Most attempts to develop effective sampling protocols have focused upon the aflatoxins, since the majority of current regulations are concerned specifically with this group of mycotoxins. However, the design of effective sampling protocols has been severely hindered by the highly skewed distribution of the aflatoxins in foods and feeds. Studies already performed indicate that representative samples of commodities, composed of large particles (e.g., corn and oilseed kernels) should be 10 kg in weight, at least, and composed of approximately one hundred incremental samples. Similar studies have indicated that samples of oilseed cakes and meal, however, should be composed of fifty incremental samples which afford a composite sample of approximately 5 kg in weight.

Reaction to a paper by Whitaker and Dickens on aflatoxin testing plans for shelled peanuts in the U.S. and the export market.

The present paper examines a technical paper of Whitaker and Dickens on aflatoxin testing plans that discusses (without a literature reference) a testing plan used in The Netherlands. However, this testing plan has never been in operation. We present the current situation in The Netherlands with respect to legislation and sampling plans on aflatoxin, which has fairly important consequences for the results of the simulation study of Whitaker and Dickens. It is shown that the percentage of rejected U.S.-exported lots in The Netherlands would increase from 16% to 27% based on the actual testing plan in The Netherlands. The need for international harmonization of testing, and the role of Codex Allmentarius is also emphasized.

Importance of ewe/lamb relationship and breed in the epidemiology of maedi-visna virus infections.

Sheep from a closed experimental breeding flock containing Finnish Landrace, Ile de France, their F1 crossbreeds, and a new breed were tested for antibodies to maedi-visna virus in 1975 and 1985-86. Over the years, the percentage of seropositive sheep increased: the Ile de France, however, remained virtually negative. Since exposure to the virus was similar, the results indicated a breed-associated difference in susceptibility to maedi-visna virus infection. Analysis of the serological results of 1985-86 yielded a total of 173 dam/progeny pairs. A significant (P less than 0.05) association between the test results of the dams and their progeny was found: seropositive (infected) dams produced 36.6 per cent positive progeny, whereas the seronegative dams had 20.0 per cent positive progeny (odds ratio = 2.3). Further analysis showed that this association was most apparent between dams and their youngest progeny, which is explained by the fact that the chance of infection by horizontal transmission increases with age. These results provide evidence that the ewe/lamb relationship plays a role in the epidemiology of maedi-visna virus infections.