ABSTRACT

Aflatoxins are toxic chemicals produced by the fungus Aspergillus flavus. Federal regulations limit uses of aflatoxin-contaminated cottonseed and cottonseed with 20 ppb or higher is not allowed into the dairy market. A total of 36,716 truckloads of cottonseed from 35 gins received at the Valley Co-op Oil Mill in Harlingen, TX during the years of 1997 to 2001 were analyzed for aflatoxin content. South Texas was divided into five regions: Rio Grande Valley, South Coastal Bend, North Coastal Bend, Upper Coast and Winter Garden. The 1999 season had the highest levels of contamination with an average aflatoxin content of 112.3 ppb and 66% of the cottonseed truckloads exceeding 20 ppb. The lowest levels of aflatoxin contamination occurred in the years 1997 and 2000 with an average of 24 ppb, while the lowest incidence (15.5%) of the truckloads exceeding an aflatoxin content of 20 ppb occurred in 1997. In general, aflatoxin contamination increased as the ginning season progressed. Rainfall after boll opening correlated highly with aflatoxin content and rain during July had the highest influence. Geostatistical analyses revealed recurrent patterns of aflatoxin contamination. Greatest contamination occurred from the central Coastal Bend region through the southern Upper Coast region. The Rio Grande Valley region experienced the least contamination during the study period.