Michel Focant

Probiotics in animal nutrition: a review.

The normal microflora colonizing the digestive tract in livestock species at five to six days after birth can be summarized as following: 400 to 500 different bacterial strains for a total count of 10(14) bacteriae. The role of the gut flora is multifarious: fermentation of feed compounds, induction of anatomical and physiological changes in the intestinal cell wall structure, increase in animal resistance against enteropathogenic bacteriae, etc. In the present review, the numerous hypotheses for explaining the beneficial effects of probiotics on zootechnical performances and also the healthy aspects for men and animals are summarized, and the possible mechanisms of bacterial attachment are enumerated. The different assumptions on mode of action and fixation mechanisms of probiotics in the gut are critically discussed, and the required characteristics of the ideal probiotic are listed. Finally, some zootechnical results obtained with lactic acid bacteria are shown for calves, piglets and broilers.

The effect of two heat treatments (steam flaking and extrusion) on the digestion of Pisum sativum in the stomachs of heifers

Six Friesian heifers weighing 546 kg body weight and fitted with permanent ruminal and duodenal cannulae were used in a cross-over design to study the effect of steam flaking and extrusion of peas (Pisum sativum) on ruminal fermentation, and starch, nitrogen and amino acid flow to the duodenum. Ground (GP), steam-flaked (SFP) and extruded peas (EXP) were fed in diets composed of 39% peas, 32% dried sugar beet pulp and 25% wheat straw supplemented with vitamins and minerals. Chromic oxide, polyethylene glycol and diaminopimelic acid were used as particulate, liquid and bacterial markers, respectively. Steam flaking did not significantly affect any of the parameters studied in vivo. Extrusion of pea decreased N solubility and gelatinized starch without a negative effect on N pepsin solubility and lysine bioavailability. The total volatile fatty acid concentration was higher for EXP than for GP (98.5 and 87.3 mM l−1; P 0.05), bacterial N (104 vs. 68 g day−1; P<0.01), non-ammonia N (185 vs. 136 g day−1; P<0.001) and flow of all amino acids to the duodenum (P<0.01).

Influence of steam flaking wheat on rumen fermentations and duodenal nitrogen and amino acid flows in heifers

Six Friesian heifers of 491 kg body weight and fitted with permanent ruminal and duodenal cannulae were used in a cross-over design to study the effect of steam flaking of wheat on ruminal fermentations and amino acid flow at the duodenum. Dry-rolled wheat (DRW) and steam-flaked wheat (SFW) were fed in diets composed of 74% wheat and 20% wheat straw supplemented with urea, vitamins and minerals. Chromium oxide, polyethylene glycol and diaminopimelic acid were used as particulate, liquid and bacterial markers, respectively. Non-ammonia nitrogen flow to the duodenum (110.3 and 98.4 g day−1) was higher (P < 0.05) for SFW compared with DRW. Duodenal flow of essential, non-essential and total amino acids was 249 and 220, 345 and 293, and 594 and 513 g day−1 for SFW and DRW, respectively, with SFW higher (P < 0.05) than DRW.

Effects of Dietary Date Pulp On Digestion in the Rat

On a dry matter (DM) basis, the date pulp (DP) used in our experiments was composed of 10% crude protein (CP), 2% fat and 63% total dietary fibre (TDF). The latter included 53% lignocellulose (acid detergent fibre, ADF), 38% lignin (acid detergent lignin, ADL) and 15% crude fibre (CF). The DP was considered as a source of water-insoluble fibre. Twelve male Wistar rats (3 months old, 312 g mean liveweight) were used. A semi-synthetic control diet containing 2% cellulose and a 20% dried DP diet containing 15% TDF including 5% CF, were compared. Daily feed intake was 14 g. By comparison with the control diet, the apparent digestibility of the DP diet was lower with respect to the DM (79 vs. 92%), the organic matter (OM) (82 vs. 95%) and the CP (68 vs. 85%), but was higher with respect to the CF (26 vs. 11%). The faecal bulk for the animals on the control and DP diets was 1.5 and 4.3 g day-1, respectively. Mean retention time of chromium was increased from 20 to 40 h by the DP intake. All the differences were highly significant (P < 0.001).