caa a22 4500 386322236 CHVBK 20180307111630.0 cr unu---uuuuu 161130e198805 xx s 000 0 eng 10.1079/BJN19880051 doi S0007114588000534 pii (NATIONALLICENCE)cambridge-10.1079/BJN19880051 Dynamics of protozoa in the rumen of cattle [Elektronische Daten] 1. The dynamics of protozoa were studied in two groups of rumen-fistulated cattle fed on a basal diet of molasses ad lib., with oaten chaff given at 6 or 18 g/kg live weight. This diet resulted in different mixtures of protozoal species in the populations in the rumen. 2. The rumen protozoa were studied by intrarumen injections of protozoa labelled in vitro with [14CH3]choline. An indication of protozoal death and fermentation of protozoal cell residues was obtained by measuring 14C loss via the methane pool. 3. After a single injection of labelled protozoa, the decline in the specific radioactivity (μCi/g nitrogen) of the protozoal pool in the rumen indicated that first-order kinetic processes applied. Conversely the specific radioactivity of protozoa, incubated in rumen fluid, remained constant indicating no growth in vitro, presumably owing to a rapid exhaustion of essential nutrients. 4. The protozoal populations in the rumen of cattle fed on the diet with the low level of oaten chaff were mainly small ciliates; but on the higher level of chaff in the diet, the large ciliates were a higher proportion of the total protozoal population present. 5. The mean pool size of protozoa in the rumen was significantly larger and the protozoal half-life tended to be longer for cattle fed on the higher level of chaff in the diet. The apparent production rate of protozoa in cattle fed on each diet was not significantly different and there were no differences in the production rate of methane. The percentage losses of label from protozoa in the rumen via the methane pool were not significantly different on the two diets and indicated that 74% of the protozoa that were apparently irreversibly lost from the rumen could be accounted for by death and lysis in the rumen and therefore only 26% of protozoa apparently entered the lower digestive tract. Copyright © The Nutrition Society 1988 Ffoulkes D. Department of Biochemistry, Microbiology and Nutrition, University of New England, Armidale, NSW 3051, Australia Leng R. A. Department of Biochemistry, Microbiology and Nutrition, University of New England, Armidale, NSW 3051, Australia British Journal of Nutrition Cambridge University Press 59/3(1988-05), 429-436 0007-1145 59:3<429 1988 59 BJN https://doi.org/10.1079/BJN19880051 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1079/BJN19880051 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ffoulkes D. Department of Biochemistry, Microbiology and Nutrition, University of New England, Armidale, NSW 3051, Australia NATIONALLICENCE 700 1- Leng R. A. Department of Biochemistry, Microbiology and Nutrition, University of New England, Armidale, NSW 3051, Australia NATIONALLICENCE 773 0- British Journal of Nutrition Cambridge University Press 59/3(1988-05), 429-436 0007-1145 59:3<429 1988 59 BJN CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge