1. 1 Department of Zoology and Toxicology, Institute of Animal Science, Georgikon Faculty of Agriculture, University of Veszprém H-8361 Keszthely, P.O. Box 71, Hungary
2. 2 Department of Zoology and Toxicology, Institute of Animal Science, Georgikon Faculty of Agriculture, University of Veszprém H-8361 Keszthely, P.O. Box 71, Hungary
3. 3 Department of Zoology and Toxicology, Institute of Animal Science, Georgikon Faculty of Agriculture, University of Veszprém H-8361 Keszthely, P.O. Box 71, Hungary