Kinetics of large ciliate protozoa in the rumen of cattle given sugar cane diets

Abstract

1. Experiments were undertaken to examine the kinetics of large ciliate protozoa in the rumen of cattle on sugar-cane diets.2. Three Zebu bulls were fed once daily on a diet of sugar cane and wheat bran. The diurnal patterns of volatile fatty acids and amm0n.a concentrations, and the numbers of protozoa in rumen fluid were determined. The numbers of protozoa re.iched values of 5 x l(r/ml for holotrichs (large ciliates) mainly Isotrichu and Dasytrichu spp and 4 x 105 for smaller protozoa, mainly Entodiniu (small ciliates).3. A method was delieloped which allowed large ciliate protozoa in rumen fluid to be separated from plant material and bacteria ar.d concentrated in a relatively uncontaminated form. Analysis of these protozoa indicated that 1.8 x 10' large ciliates contained 1 mg nitrogen and approximately 32 mg dry matter.4. A labelled preparation consisting tnainly of large ciliates (principally Zsotrichn spp.) was obtained by incubating isolated protozoa in rumen fluid (free of plant materials) containing [14C-methyl]choline and then isolating them by sedimentation and differential centrifugation.5. A portion of the preparation containing labelled protozoa was incubated in vitro with rumen fluid to determine the turnover of "C-labelled metabolites. There was no apparent dilution of the label in the protozoa over a 22 h period.6. A major portion of the preparation containing labelled protozoa was returned to the rumen of each of the donor cattle as a single injection. The specific radioactivity in the large protozoa @Ci/mg N) was monitored frequently for over 30 h, and thereafter daily for a further 12 d. The kinetics of tracer dilution were analyzed to give estimates of the size of the pool of these large ciliates in the rumen (2446 g N), and of their apparent rate of turnover.7. In contrast to thi: slow turnover of the large ciliates, the rate of turnover of the rumen fluid pool (approximately 54 I), esimated from the rate of dilution of polyethylene glycol, was considerably faster. Large ciliates were therefore wlectively retained within the rumen.Involvement of protozoa in the nutrition of ruminants has been studied mainly in animals in which small ciliate protozoa (Entodinia spp.) rather than the large ciliate protozoa (Holotricha spp.) wcre predominant in the population. The smaller protozoa actively engulf bacteria (Coleman, 1975), and do not pass out of the rumen in proportion to their concentration in rumen fluid (Weller & Pilgrim, 1974;Harrison et al. 1979). It has been suggested that these characteristics may reduce nutrient availability to the host animal Bergeii & Yokoyama, 1977) particularly on low-protein diets. Elimination of protozoa from the :umen has increased the growth rates and efficiency of food utilization for live-weight gain (Bird'& Leng, 1978;Bird et al. 1979) indicating that under some circumstances the presence of protozoa in the rumen reduces animal productivity.In cattle given sugar cane diets (Valdez et al. 1977) or grazing some temperate pastures (Clarke, 1965), although th...

Effects of dietary energy and nitrogen supplements on rumen fermentation and protozoa population in buffalo and zebu cattle

“…Usually, cattle on diets based on sugar cane maintain high percentages of holotricha ciliates in the rumen (Valdez et al, 1977;Fernandez et al, 1980;Leng et al, 1981;Valvasori et al, 2001) because these species are able to ferment many simple carbohydrates (Dehority, 2003). There was higher Dasytricha composition in the rumen ciliate population in the cattle (mean 11.5%) than in the buffaloes (mean 2.6%).…”

Effect of ruminal inoculation of Isotricha alone or a mixed B-type fauna in a defaunated rumen on the digestion of a hay-maize diet (70:30) in sheep

“…Samples of rumen fluid (5 ml) containing 5% (w/v) solution of orthophosphoric acid were kept at -15°C. Two milliliters of rumen fluid were mixed with 8 ml of a 12.5% (w/v) (Warner, 1962 (Leng et al, 1981) and that the mean content of N in their DM was close to 6.0% (Jouany and Thivend, 1972). We also assumed that the volume, and therefore the weight, of small entodinia was 100 times less that of the large ciliates.…”

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

“…The corresponding biomass was calculated from the estimations of Leng et al (1981) and Broad and Dawson (1975) Van Soest and Wine (1967).…”