RUMEN FERMENTATION AND METABOLIC PROFILE IN CONVENTIONAL AND GNOTOBIOTIC LAMBS

Observations were carried out of actual acidity, volatile fatty acid ( VFA) concentrations, enzyme activity in the rumen, total protein, urea , total lipid and glucose in the serum of conventional (CL) and gnotob iotic lambs (GL) in the period of milk nutrition. The inoculum of gnot obiotic lambs contained Streptococcus bovis, Prevoxella ruminicola, Bu tyrivibrio fibrisolvens and Selenomonas ruminantium at a concentration of 1.10(6) each. Throughout the observation period the pH of the rume n contents of gnotobiotic lambs ranged within 6.5-6.8 with a significa nt difference at an age of 7 weeks. Total VFA concentrations in the ru men contents were increased in the CL throughout milk nutrition; the d ifferences at 4 and 5 weeks of age were significant. Total VFA in the conventional lambs revealed an increasing tendency between weeks 4 and 7, reaching higher levels at 7 weeks of age (57.1 mmol.l(-1)), wherea s in the gnotobiotic animals the range (24.3-30.1 mmol.l(-1)) was narr ow and the peak occurred at 6 weeks of age. In GL significantly increa sed molar proportions of acetic acid were observed whereas in CL the m olar proportions of propionic acid proved to be significant increased. The molar proportions of butyric and valeric acids were increased in CL but the group differences were not significant. In GL no isoacids w ere found. Alpha amylase (E.C.3.2.1.1.) activity of the rumen contents was significantly increased in GL between weeks 2 and 6 of age wherea s cellulase (endoglucanase E.C.3.2.1.4. and cellobiohydrolase E.C.3.2. 1.91.) activity was significantly increased in 4-week-old CL. Over the whole period of milk nutrition no significant differences were observ ed in urease (E.C.3.5.1.5.) activity of the rumen contents in the exam ined groups. At 5 weeks of age significantly increased total protein l evels were observed in the conventional animals with maximum levels oc curring at 4 weeks of age (CL-59.5 g.l(-1) GL-55.3 g.l(-1)). Urea leve ls in 6-week old conventional lambs were significantly higher than in the gnotobiotic animals (CL-6.4 mmol.l(-1) vs. GL-1.9 mmol.l(-1)). As to glycaemia no significant group differences were recorded. In the co nventional animals total lipid levels were significantly increased at 1 and 6 weeks of age with a peak occurring in the first week of life ( 7.5 g.l(-1)) whereas in the gnotobiotic lambs a significant increase w as observed at 3 weeks of age, the peak being recorded in 4 week-old a nimals (4.3 g.l(-1)). Throughout the period of interest the mean daily weight gains in the conventional and gnotobiotic lambs presented 0.16 4 and 0.162 kg, respectively. The functional development of the rumen was significantly influenced by the complexity of the microflora.