Diurnal Changes in the Concentrations of Micro-organisms in the Rumens of Sheep Fed Limited Diets Once Daily: WITH AN APPENDIX ON THE KINETICS OF RUMEN MICROBES AND FLOW

Abstract

SUMMARYThe pattern of change of concentration of different groups of microorganisms in the rumen was found to be characteristic of the group and little affected by the time of day, the nature of the diet, or the host animal. The dilution rate of rumen liquor and the rate of change of concentration of several groups of micro-organisms were measured a t intervals following feeding; this allowed calculation of the apparent specific growth rate. The changes in concentration of the ophryoscolecid ciliate protozoa, the selenomonads and the oval organism described by Eadie could be explained as the resultant of the changes in dilution rate due to the act of eating and in growth rate in response to incoming nutrients. Rates of change in concentration greater than could be accounted for on the basis of growth and dilution alone were found with the peptostreptococci, the polymastigate flagellate protozoa and the holotrich ciliate protozoa. It is suggested that the peptostreptococci underwent lysis or engulfment by other organisms and that the polymastigates became sequestered, .probably close to the rumen wall. The concentration changes of the holotrichs were more difficult t o understand, but it would appear that little division took place for some 18 hr after feeding, followed by several divisions in quick succession. The oscillospirae showed two peaks in concentration; no explanation can be offered for this.

The Effects of Feeding Soybean Meal, Soybean Hulls and Raw Soybean Seed on Rumen Microbial Populations and Ruminal Fermentation in Grazing Dairy Cows

“…A significant treatment by time interaction was detected in that the concentration of protozoa was significantly lower for SH treatment only at T0. All three treatments showed similar quadratic curves, i.e., a decrease in concentration at 3 h post feeding followed by a slight increase at 6 h. This behaviour agrees with the diurnal changes reported 26,27,28 and might indicate the dilution effect from eating. However, methanogenic bacteria were not determined in this study because of the symbiotic relationship between protozoa and methanogenic bacteria; it was described 15 that the decrease in the number of protozoa when the animals were fed the SH diet could suggest a decrease in the number of methanogenic bacteria which in turn would lead to an increased production of propionic acid 15 .…”

Studies on the Rumen Flagellate Neocallimastix frontalis

“…The entire cycle occurs within the rumen and the organism could be cultured in vitro; the conditions under which maximum reproduction occurred (39 "C, pH 6.5, absence of oxygen, presence of CO,) indicated that neocallimastix is a true rumen organism since conditions within the rumen are essentially similar (Hungate, 1966). This is supported by the wide distribution of neocallimastix in ruminants (Braune, 1913;Das Gupta, 1935;Eadie, 1962;Warner, 1966). The possession of a rhizoid by the reproductive body shows that the organism may be fungal rather than protozoal ; protozoal reproductive bodies do not normally possess rhizoids.…”

“…Fluctuations as high as this are abnormal for rumen organisms, which normally divide only 2 to 4 times a day (Hungate, 1966). Warner (1966) suggested that the cause of this dramatic fluctuation was that the neocallimastix were normally sequestered on the rumen wall, entered the rumen fluid in response to a chemical stimulus in the diet and later returned to the wall by another chemotactic response, possibly to a compound diffusing from the blood into the rumen. This theory was discounted by Orpin (1974) who showed that the neocallimastix population density could be increased in vivo and in vitro by an extract of oats.…”

“…4). Since such a decrease is common in rumen organisms over the feeding period of the host, due to dilution of the rumen contents (Warner, 1966), the dilution was measured using PEG. This showed that a 25 % dilution occurred within I h of the animal commencing to eat, and therefore a 25 % reduction in sporangia concentration would have occurred.…”

Anaerobic fungi in the digestive tract of mammalian herbivores and their potential for exploitation

“…In fact, zoospores of anaerobic fungi were known since the early part of this century but were mistakenly identified as protozoan flagellates in rumen fluid (Liebetanz, 1910). According to Warner (1966), these flagellates were sequestered on the rumen epithelium, moving to the rumen fluid when the animal was feeding. This hypothesis was necessary to account for the large increase in protozoan flagellates in rumen fluid immediately after feeding.…”