Effect of dietary fructose polymers or sucrose on microbial fermentation, enzyme activity, ciliate concentration and diversity of bacterial flora in the rumen of rams

Abstract Five rumen-cannulated Polish Merino rams were used in a 5 × 5 Latin square design to investigate the effect of sucrose and polymers of fructose on the activity and characteristics of rumen protozoa and bacteria. The animals were fed concentrate and timothy hay containing either 33 g or 163 g fructan/kg. The low-fructan hay was supplied in the control diet and in the diets supplemented with sucrose and inulins. The high-fructan hay was the component of diet rich in timothy grass fructan. The control diet supplied 39.6 g fructan/day. The remaining diet offered 195.6 g of fructose-containing carbohydrates/day. The concentration of total SCFA was 7.2–9.5 mM/100 ml rumen fluid independently of diet and sampling time (P>0.05). The increase in sucrose or fructan contents lowered the proportions of acetate from 73.1 to 64.2 mM/100 mM (P≤0.002) and increased those of propionate and butyrate from 16.4 to 21.5 (P=0.003), and from 9.8 to 15.6 mM/100 mM (P≤0.004), respectively. The sampling time affected the proportions of propionate (P=0.01). The diets did not affect pH of rumen fluid except in the ration with timothy grass fructan (P=0.029). Irrespective of diet and sampling time (P≥0.05), the digestion velocities of timothy grass fructan, inulin, sucrose, starch, pectins, carboxymethylcellulose, and xylan were 1.3–2.9; 0.7–2.1; 4.8–9.6; 1.9–2.4, 0.3–0.5, 0.7–1.2, and 0.7–1.4 mM reducing sugars/g dry matter (DM) of rumen fluid per hour, respectively. A positive correlation was found between the degradation rate of timothy grass fructan and inulin or sucrose (P≤0.045). The total number of ciliates was 261–475×10 3 /ml, that of Entodinium , 231–439×10 3 /ml. The concentrations of Epidinium , Isotricha and Dasytricha were 14–24×10 3 /ml, 2.6–7.0×10 3 /ml, and 3.2–8.1×10 3 /ml, respectively (P≥0.05). The Diplodinium counts varied from 1.4 to 3.1×10 3 /ml in control animals to 4.0–7.3×10 3 /ml in sheep fed the diet rich in timothy grass fructan and Beneo P95 (P≤0.008). A postprandial decrease in the concentration of Diplodiniuum was found in animals fed the control ration and the rations rich in timothy grass fructan and Beneo HPX (P=0.017). It was stated that the sampling time influenced the composition of bacterial flora. The experiment showed that the applied doses of the examined carbohydrates did not affect the majority of the quantified parameters. The studies shall be continued using enlarged doses of fructose-containing carbohydrates.