Recent findings and future perspectives of digestive physiology in rabbits: a review

The rabbit is one of the most common laboratory animals. Consequently, there is an enormous number of publications concerning its physiology. The present review is restricted to a special field and deals with the new findings of the rabbit's digestive physiology. For the sake of better intelligibility the most important antecedents are also given. First the particularities of feed intake regulation are demonstrated. The strong control mechanism can be disturbed by feed antinutritives, mycotoxins and high environmental temperature. Caecotrophy depends on three main factors: stimulation of rectal mechanoreceptors, perception of the specific odour of the soft faeces, and the inner motive determined by the blood level of metabolites and hormones. The species characteristics of proportions, pH conditions, microflora and -fauna of the rabbit's digestive tract are given. The digestion and absorption of dietary nutrients are discussed. Special sections deal with the sorption of electrolytes and VFAs in the gut, the caecal digestive process, the formation of hard and soft faeces and the role of the caecotrophy in stomachal carbohydrate degradation. A relatively new area, i.e. the development and maturation of the gastrointestinal tract, is also shown. The postnatal evolution of digestive enzyme activity is also summarized. The main endogenic factors (breed, sex, age, stress, caecotrophy, presence of hairball in the stomach) influencing the digestion of dietary nutrients are also described. The probable future trends are given, too.