The agricultural harvester (1) has working assemblies (3-5) for processing and conveying crop (10). A sensor array (9) detects a hazardous substance (18) in the crop to be processed. The hazardous substance is a substance that renders the crop unsuitable in terms of animal feed. The hazardous substance is an animal substance. The sensor array comprises an optical sensor that optically detects the processed crop in order to derive information regarding the presence of hazardous substance.
