Production of volatile fatty acids (VFA) in the rabbit’s digestive tract is connected with implantation of cellulolitic flora, which takes place abort the third week of life. VFA are produced as a result of fermentation of dietary fibre (partly NDF – neutral detergent fibre, partly pectins and water-soluble fibre), as well as from other food components and endogenous material. The volume of these acids in the rabbit’s caecum reaches its normal level after the 40 days of life and ranges on the average from 31,8 to 88,5 mmol/dm³, with the simultaneous reversal of the propionate acid to butyric acid ratio. In this gut the VFA profile is specific, with a predominance of acetate (60-80 mol in 100 mol of the VFA produced), smaller amount of butyrate (8-20 mol/100 mol VFA) and an even smaller amount of propionate (3-10 mol/100 mol VFA). The day cycle of fermentation in the rabbit’s caecum overlaps closely with the parallel rhythm of absorption and metabolism of volatile fatty acids. The large intestine tissues metabolize best butyrate, than propionate and in the smallest degree acetate. All volatile fatty acids are utilized as a source of energy for the basic metabolism (they cover 30-40% of the organism’s requirement). Apart from supplying metabolic energy, VFA also have manifold effects on the mucosa of the large intestine. They influence among others the increase in inter-cellular pH or cell swelling, they modulate absorption of sodium and secretion of chlorine, they stimulate release of mucins and enhance the blood flow in mucosa. It is also supposed that volatile fatty acids stimulate the growth of colonic mucosa. Research is in progress on application of VFA in therapy of various large intestine disorders.

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