To improve intestinal function, the digestibility of foods, the body of the rabbit need fiber. Experiments proved if the feed would contain only 5% of fiber, there is a 40% risk of gastro-intestinal diseases, and if 13% fat, bowel problems will be only 28.7%. Rabbits digest fiber, as well as pigs, however, is small compared with other herbivores. Fiber digested in small quantities in forage and bran 17 – 25%, in the green and grain – 40-50%. By reducing the amount of feed in up to 9%, the rabbits begin to ache, and sometimes adversely affects neither their reproducibility. The best solution if the feed fiber content is between 15 and 20% for adults, 10 – 16% for lactating rabbits and 12 – 15% for the rabbits.
As mentioned earlier, fiber occupies one of the top positions for the life and health of rabbits, though absorbed in the small percentage, however, it contributes to the work of the intestines to digest food. In contrast, ruminant animals, rabbits poorly digested feed, saturated cellulose, their dosage must be less than for cattle and sheep. If the portions of food for young rabbits contains less than 12% of pulp per 1 kg of body weight, there is a risk of disruption of the gastrointestinal system. Including food products lungs with a high percentage of protein and lower amount of the cellulose, the body replenishes nitrogen decay products entering the body, it is absorbed into the blood and increases the percentage of nitrogen-containing substances. Changing the formula of blood and animals occurs diarrhea, there were even deaths due to poisoning of the body with plenty of ammonia. More fiber in the diet for rabbits leads to consumption of more small animals food, but it is not profitable economically in turn.