STIMULATION OF RUMEN FERMENTATION IN SUCK ING LAMBS

The effect of administration of a preparation containing nutrients and growth which stimulate rumen bacteria was investigated with respect t o the level of rumen fermentation in sucking lambs. The preparation wa s administered orally at a dose of 1.5 g per lamb/day to lambs at the age of 1 to 6 weeks. In addition to genuine milk, both groups of lambs received a concentrate mixture and had free choice of hay and water. Two lambs from the experimental group and two lambs from the control g roup were slaughtered at the age of 1, 4, 6, 10 weeks. The average dai ly weight gains over the period of 1 to 4 weeks were 0. 179 kg in the control and experimental groups, 0.212 kg in the experimental group at the age of six weeks, and 0.189 kg in the control group at the same a ge while over the whole period of investigation they were 0.209 kg and 0. 1 84 kg in the experimental and control group, respectively. The d ynamics of total volatile fatty acid concentrations (Fig. 1) showed an increasing trend in both investigated groups with the growing age whi le the highest values (I 25.9 +/-8.5 mmol/l in the control group and 1 30.7 +/- 17.2 mmol % in the experimental group) were recorded at the a ge of 10 weeks. The between-the-group differences were not significant . As for the percentage of individual volatile fatty acids, the larges t differences were observed in propionate and valerate. The percentage of propionate (Fig. 2) was increasing with the growing age of lambs o f the experimental group, and this difference enlarged in favour of th e experimental group. At the age of 10 weeks, the molar proportion of propionate was on average 21.5 +/- 4.1 mol % in the experimental group , and only 16.3 +/- 2.9 mol % in the control group. The valerate value s were highest in both investigated groups at the age of four weeks (2 .03 +/- 0.7 mol % in the experimental group and 1.4 +/- 0.2 mol % in t he control group; Fig. 3). There were not any larger differences in th e percentages of the other VFA. The energetic efficiency of VFA produc tion (E %) showed the higher values in the lambs of experimental group in the course of preparation administration and after its termination , and the acetate to propionate ratio (A : P) was lower than in the co ntrol group (Fig. 4). The differences were largest at the age of ten w eeks, when the energetic efficiency of VFA production was on average 7 4.9 +/- 1.6 % in the experimental group, and 72.5 +/- 1.0 % in the con trol group, while the acetate : propionate ratios were 3.1 +/- 0.6 and 4.4 +/- 0.7 in the experimental and control group, respectively. The energetic efficiency of VFA production was rising in the lambs of expe rimental group during the whole period of investigation, and on the ot her hand the acetate : propionate ratio was decreasing. In the lambs o f control group the energetic efficiency of VFA was increasing and the acetate : propionate ratio in the rumen was decreasing to the age of six weeks only. The alpha-amylase (E.C.3.2.1.1.) activity of the rumen fluid of sucking lambs (Fig. 5) showed an increasing trend with the g rowing age in both investigated groups, with the largest differences i n favour of the experimental group at the age of six weeks (1.76 +/-0. 04 mukat/1 in the control group, 2.7 +/- 0.5 mukat/I in the experiment al group) and at the age of 1 0 weeks (2.2 mukat/l in the control grou p and 3.1 +/- 0.1 mukat/1 in the experimental group;p < 0.05). The alp ha-amylase activity of rumen epithelium had an increasing trend in the experimental group to the age of six weeks, when it reached threefold values in comparison with the control group (control group 0.86 +/- 0 .2 mukat/cm2, experimental group 2.7 +/- 1.0 nkat/cM2). In the control group, the peak of alpha-amylase activity was recorded on average at the age of four weeks (1.5 +/- 0.7 nkat/cm2), then the activity decrea sed. The counts of streptococci and lactobacilli in the rumen fluid an d of those adhered to the rumen epithelium (Fig. 6) were significantly higher (p < 0.05 and p < 0.001) in the lambs of the experimental grou p. The highest counts of bacteria over the whole period of investigati on were determined in the experimental group at the age of six weeks ( streptococci-rumen fluid: 6.76 log 1 0/ml, rumen epithelium: 6.16 log 1 0/ml, lactobacilli-rumen fluid: 4.9 log 1 0/ml, rumen epithelium 4.7 6 log 1 0/ml). The counts of amylolytic bacteria in the rumen fluid we re significantly (p < 0.05) higher in the lambs of experimental group at the age of four and ten weeks (Fig. 7), with the highest values at the end of the period of investigation (8.05 log 1 0/ml). The photos t aken by scanning electrone microscopy show that the rumen papillae of an experimental lamb at the age of four weeks (Fig. 9) are longer and more differentiated in comparison with a lamb of control group (Fig. 8 ).