Observations on the microbiology and biochemistry of the rumen in cattle given different quantities of a pelleted barley ration

Abstract

I. Three heifers were changed from a diet of equal parts of hay and barley cubes (50:~o diet) to one entirely of barley cubes given in three equal feeds throughout the day. Feed intake was restricted to 80 % of calculated appetite at the time of change and this percentage progressively decreased as the live weights of the animals increased.2. The change of diet had no significant effect on the volume of rumen fluid but the rate of outflow from the rumen was significantly lower on the barley diet than on the 50: 50 diet.3. Animals on the restricted barley diet developed an exceptionally high rumen ciliate population and the bacterial population was shown by Gram films to include a number of organisms typical of roughage-fed animals. In culture, organisms of the genus Bacteroides were predominant but these appeared largely as cocco-bacilli in the Gram films. This microbial population was associated with a higher proportion of butyric acid than of propionic acid in the rumen fluid.4. Occasional fluctuations in ciliate populations occurred in all three heifers. Decreases in ciliate number were paralleled by increases in propionic acid and decreases in butyric acid but not necessarily by a fall in pH. Under these conditions Gram films showed increases in bacteriodes-type rods and in certain curved Gram-negative rods.5. Rumen ammonia concentrations were on average lower and showed a different diurnal pattern when ciliate numbers were reduced. Lactic acid concentrations were low and were not affected by the size of the ciliate population.6. When the three heifers were given the barley diet ad lib. there was a decrease in rumen pH and a complete loss of rumen ciliates. The rumen bacterial population and the volatile fatty acid proportions were similar to those seen during decreases in ciliate number at the restricted level of intake. These changes also occurred in a fourth heifer which was changed fairly rapidly from the 50: 50 diet to a restricted amount of the barley diet. 7.Two steers which had never had access to roughage were changed from ad lib. to restricted intake of the barley diet and were later given an inoculum of rumen ciliates. The rumen microbial population and the pattern of fermentation so produced were similar to those found in the heifers on the restricted barley diet.8. Anomalous values were noted for total counts of rumen bacteria when free starch grains were present in the rumen fluid.9. It is concluded that large ciliate populations and high proportions of butyric acid can be produced in animals fed exclusively on a barley diet by suitable adjustment of the intake and the method of feeding. I t is postulated that the ciliate population may be largely responsible for the high butyric acid concentrations.The rumen microbial populations of mature steers given ad lib. access to a barley diet have been described by Eadie, Hobson & Mann (1967) and have been shown to be similar in many respects to those found in young ruminating calves given large amounts of starchy concentrates (Eadie, 1962). A complete...

Digestion of a dehydrated lucerne/barley diet (70:30) in defaunated, Isotricha-monoinoculated and mixed-fauna-inoculated rumen in sheep

“…The increased butyrate proportion of the VFA mixture in the faunated sheep, at the expense of propionate and valerate, is consistent with previously published results (Jouany et al, 1988). This trend was less marked in Isotricha-monoinoculated sheep than in mixed-faunated sheep, and is probably the direct consequence of butyrate production by the entodiniomorphid ciliates (Eadie et al, 1970). On the other hand, the lactate that could be produced with such diets was never detected in the sheep rumen juice throughout the experiment.…”

“…It is generally accepted that highly acidic pH values in the rumen can inhibit the growth of ciliates (Purser and Moir, 1959) and may even cause their complete elimination (Eadie et al, 1970;Whitelaw et al, 1972;Rung et al, 1986). The decline in the number of entodiniomorphid ciliates noted here during the 3 h following the meal in the rumen juice was always observed in the numerous experiments we carried out.…”

Dietary carbohydrate composition modifies the milk N efficiency in late lactation cows fed low crude protein diets

“…On the other hand, in absence of increased mobilization of adipose tissues, as suggested by measured plasma NEFA concentrations and the calculated energy balance, the higher plasma BHBA concentrations likely arise from increased butyrate absorption and conversion to BHBA in the rumen wall (Kristensen et al, 2000). Because animals were fed every 3 h at restricted intake levels, the possibility of a subacute butyric acidosis associated with starch diets (Eadie et al, 1970) should be considered here. Results from the aforementioned metabolic trial (Cantalapiedra-Hijar et al, 2013) confirmed an almost twofold higher butyrate net portal absorption for starch compared with fiber diets.…”

Effect of Monensin on Ruminal VFA and Gas Production of Sheep Fed High Concentrate Diet

“…Which species of bacteria increased in its number according to the decrease in protozoal number was not shown in that report. However increase of starch digesting bacteria by the defaunation was reported13) and EADIE et al 6) also observed that the increase in the number of Bacteroides-type rods and Selenomonas ruminantium was associated with the reduction in protozoal number. Those groups of bacteria produce mainly propionic acid or its precursors.…”