Extruded diets are claimed to be more digestible, palatable and of a higher hygienic standard compared to pelleted diets. In a comparision of a pelleted and an extruded diet given to Sprague-Dawley rats, we found no difference in weight gain, feed and water consumption or in blood glucose level. In the microbiological analyses, there was no major difference either. When considering choice of diet the physical form seems to be of minor importance. The major factors should be the nutritional value, hygienic level (autoclavable or irradiated vs conventional), reproduciability, availability, confidence in producer and economical values
