Characterization of the microbial and biochemical profile of the different segments of the digestive tract in horses given two distinct diets

Abstract : A first group of three horses was given diet 1 (D1) allowing 1180 g per 100 kg body weight (BW) of a pelleted foodrich in fibre (P1) and 556 g per 100 kg BW of straw during a 20-day period to allow for adaptation. A second groupof four horses were given diet 2 (D2) allowing 1180 g per 100 kg BW of a pelleted food rich in cereals (P2) and1000 g per 100 kg BW of meadow hay during the same period. Digesta was collected from the stomach, duodenum,jejunum, ileum, caecum, right ventral colon, left ventral colon, left dorsal colon, right dorsal colon, and small colon,and faeces were collected under general anaesthesia 2·5 h after the ingestion of the morning pelleted meal. Theconcentration of total anaerobic, cellulolytic and lactic acid-utilizing bacteria, lactobacilli and streptococci weredetermined in all these segments except for the duodenum, left ventral colon, right dorsal colon and small colon. D-/L-lactic acid, volatile fatty acids and pH were measured in all anatomic segments of the digestive tract (from stomach tosmall colon). The caecal concentration of total anaerobic bacteria was the lowest (7⋅95 107 colony-forming units (c. f.u. ) per ml), whereas that of the stomach was the highest (1·45 109 c. f. u. per ml) (P < 0⋅001). Cellulolytic bacteriadid not exceed 3·05 102 c. f. u. per ml in the ante-caecal segments whereas in the hindgut the average concentrationwas 5·3 ×105 c. f. u. per ml (P < 0⋅001). Likewise, VFA concentrations were also greater in the large intestine (onaverage, 96·3 mmol/lv. 8·8 mmol/l in the ante-caecal segments) (P < 0⋅001), confirming the limited extent of fibredegradation in these ante-caecal segments. Lactobacilli, streptococci and lactate-utilizing bacteria colonized all thedigestive tract; the stomach and the small intestine tended to host the greatest numbers of these bacteria, whichsuggests a high interference of micro-organisms with the digestion of readily fermentable carbohydrates. Comparedwith the other ante-caecal segments, the stomach ecosystem seemed the most affected by the composition of the lastpelleted meal ingested : the concentrations of lactobacilli and lactate-utilizing bacteria were higher (P < 0⋅05) withP2. The lower concentration of D-/L-lactate with P2 (P < 0⋅05) was concomitant with a greater proportion ofpropionate (P < 0⋅05), probably related to a greater fermentation of lactate. In the large intestine of horses given D2,cellulolytic bacteria tended to be lower, whereas VFA concentrations were higher (P < 0⋅05). The lower [NDF/starch]ratio of D2 was probably less propitious for the proliferation of cellulolytic bacteria but was compensated by thehigher cellulose intake brought by the hay.
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Submitted on : Tuesday, July 10, 2018 - 10:18:09 AM
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  • HAL Id : hal-01833993, version 1

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A. Fombelle De,, Marie Varloud, A.G. Goachet, Emmanuel Jacotot, Christelle Philippeau, et al.. Characterization of the microbial and biochemical profile of the different segments of the digestive tract in horses given two distinct diets. Animal Science, Cambridge University Press (CUP), 2003, pp.293-304. ⟨hal-01833993⟩

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