Digestion, chez le lapin en croissance, d'une ration à taux élevé de constituants pariétaux : étude méthodologique pour le calcul de digestibilité apparente, par segment digestif

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Abstract
A new methodology was used in growing rabbits with the aim of estimating digestion in the different segments of the digestive tract. Twenty-seven 8-week old white New Zealand rabbits received a diet rich in cell wall carbohydrates (25 p. 100 crude fibre) and lignin (11 p. 100) admixed the chromium oxide used as a marker. Digesta were collected after slaughter every 3 h for a period of 24 h from the stomach, terminal ileum, caecum and rectum. The apparent digestibility coefficients (CUDa), calculated by total collection of faeces, were low for dry matter, energy and crude protein (54-60 p. 100, table 1). Hemicelluloses (Van Soest) were better digested (CUDa = 40 p.100) than cellulose (CUDa = 30 p.100) while 16 p. 100 lignin seemed to be digested. Combining the slaughter technique with the use of food markers allowed to determine the apparent digestibility and mean retention times at the different collection sites as well as the amount of caecotrophes. Thus, the apparent digestibility of dry matter was 14 p. 100 before the caecum versus 32 p. 100 in the caecum. However, this method was not as suitable for measuring nitrogen digestion (e.g. negative CUDa in the ileum). The hypothesis of a differential passage of dietary components was put forward. The average apparent retention times (table 4) were 3-4 h for the stomach and 4-6h for the caecum. These values are lower than those of the literature. The daily amount of caecotrophes reached 15 p. 100 of the total dry matter intake and 23 p. 100 of the total crude protein intake.