avoparcin and propionic-acid

The influence of Avotan (Firm Cyanamid) was studied on VFA concentration, pH, dynamics of NH3 and on numbers of chosen species of rumen microorganisms in physiological experiments with four young bulls and two wethers with rumen cannulas. It was found no marked physiological change in pH of rumen fluid under the influence of Avotan. Difference between groups were statistical significant. Avotan caused significant (P < or = 0.01) decrease of molar % of acetic acid (from 67.0 to 62.1) and an increase of propionic acid (from 16.41 to 28.21 mol %) in wethers. These changes were nonsignificant with bulls. The acetate: propionate ratio decreased significantly from 4.1 to 2.2 in wethers. Avotan decreased highly significantly (P < or = 0.01) the level of NH3 in the rumen fluid during the observed period (0, 1.5, 3, 4.5 and 6 hours after feeding) in bulls. It was observed the similar effect in wethers 3 hours after feeding (from 170 mmol to 81 mmol/l). Decrease of the total number of microorganisms in the rumen fluid was observed in animals which received Avotan (on the average 3.5 times in young bulls, and 4.5 times in wethers). The number of enterococci decreased significantly (2.8-4.5 times), number of amylolytic bacteria decreased less significantly.

Topics: Acetates; Acetic Acid; Ammonia; Animal Feed; Animals; Anti-Bacterial Agents; Bacteria; Cattle; Diet; Fatty Acids, Volatile; Glycopeptides; Male; Propionates; Regression Analysis; Rumen; Sheep; Species Specificity

The effect of the antibiotic, avoparcin, on ruminal propionate production and amino acid degradation was investigated by using four rumen fistulated wethers. Wethers were fed each of four diets during 28-day periods in a 4 X 4 Latin square design. Diets were high fiber (HF), high fiber plus 50 ppm avoparcin (HF-AVO), low fiber (LF) and low fiber plus 50 ppm avoparcin (LF-AVO). Total digestible energy intake (1.25 X maintenance) and crude protein intake for each animal were similar for all diets. Propionate production was determined each period from all animals by using a single injection of [1-14C]propionate and polyethylene glycol. Avoparcin decreased total volatile fatty acid concentration, increased ruminal pH and molar proportions of propionate on both HF and LF diets. Daily propionate production and pool turnover rate increased in sheep fed LF-AVO. Similar changes were noted in HF-AVO animals, although they were not statistically significant. Avoparcin decreased ruminal ammonia (50 vs. 45 mg/100 ml) and increased alpha amino nitrogen (8.6 vs. 14.3 mM) in LF-fed sheep. In vitro studies demonstrated a decreased degradation of crystalline amino acids by mixed populations of rumen microorganisms from sheep receiving LF diets containing avoparcin. Avoparcin appears to modify rumen fermentation by increasing propionate production and inhibiting protein or amino acid degradation.

Topics: Amino Acids; Animal Feed; Animals; Anti-Bacterial Agents; Dietary Fiber; Fermentation; Food, Fortified; Glycopeptides; Hydrogen-Ion Concentration; Male; Propionates; Rumen; Sheep