In vivomeasurements of the production rates of bacteria in the rumen

Abstract

SummaryThe production rates of bacteria have been measured in the rumen of zebu calves and buffalo calves. The animals were fed green oat continuously at 2 h intervals. [35S]sodium sulphate was fed to the animals for 5 days at 2 h intervals by mixing in the feed. On the sixth day the radioactive feed was stopped and replaced by non-radioactive feed. The decline in the specific radioactivity of bacterial cells in the rumen as a function of time was taken for calculatingt/2. Simultaneously rumen volume was determined and pool size of bacterial cells was calculated in the rumen. A mathematical equation was applied to calculate the production rates of bacteria. The production rates of bacteria, on average, were 100·5 and 72·3 mg/min for buffalo calves and zebu calves, respectively.

Initial studies on leucine metabolism in the rumen of sheep

“…There are few reports on the disappearance rates of bacterial protein in the rumen. Singh et al (1973) labelled rumen bacteria with 35S0,-enriched feed and reported disappearance rates of activity of 2.30 and 2.68 /d from the rumen of buffalo and zebu cattle respectively. However, this technique does not measure a loss of activity from a constituent of bacterial protein.…”

“…However, this technique does not measure a loss of activity from a constituent of bacterial protein. In a second study, Singh et al (1974) added ~~-[U-'~C]leucine-labelled cultured bacteria into the rumen of buffalo calves and estimated disappearance rates of 4.46 and 4.87/d. These bacteria may, however, have failed to equilibrate between the liquid and solid phases before being washed from the rumen.…”

“…Protein in plasma (2.0 ml) was precipitated with an equal volume of trichloroacetic acid (200 g/l; TCA), the precipitate centrifuged (2000 g, 10 min) and the pellet washed twice with TCA before hydrolysis. Rumen epithelium was stripped from the rumen wall, homogenized in TCA (200 g/l) and the precipitated protein hydrolysed (Sinnett-Smith et al 1983).…”

In vivo measurement of rumen microbial growth using 35S

“…In addition, there would be significantly less analytical load than with alternative methods (e.g. Singh et al 1973;Walker & Nader, 1975). The applicability of the proposed method for animals at pasture or given feed infrequently should be further investigated.…”

“…Subsequent calculation of the amount of microbial protein that passes from the rumen or abomasum is dependent on estimation of flow rate of digesta from the rumen or into the duodenum; this usually requires total collection of digesta from re-entrant cannulae (MacRae, 1975), or collections from simple cannulae fitted to animals infused with digesta markers and given feed at frequent intervals (Faichney, 1975). Other methods, although requiring animals fitted with rumen fistulae only, are dependent on the collection of representative samples of rumen digesta (Walker & Nader, 1975) or on the assumption that all microbes are present in the liquid phase (Singh et al 1973) in order to calculate the size of the microbial pool. Alternatively, an injection of a known dose of rumen microbes, labelled with 35 S by an in vitro incubation procedure, may be made t Present address: Department of Animal Science, University of Alberta, Edmonton, Canada T6G 2E3.…”