Studies on the Ecology of Certain Rumen Ciliate Protozoa

Abstract

S U M M A R YThe times taken by Op/zryoscde.u tricovonatus and species of the genus Ej7idinium to establish in the rumens of young animals were found to differ from those of other rumen ciliate species. The antagonistic relationships between certain rumen ciliates were examined in vivo and concurrent experiments were made in small vessels termed vivars which were suspended within the rumen of a sheep. A Millipore membrane separated the rumen contents from the contents of the vivars. Within these vessels it was possible to reproduce population changes first observed in viiw and to determine with certainty that in a population change where Po/yp/astron ~u l t i v e s i c u l~t z~~n became irreversibly dominant this had been caused by predation by Polyplastron. This organism will eliminate Epidinium, Eudiplodiniunt nzaggii, Eremoplastron and Ostracodinium from ;I population. The cause, factors affecting it and the ultimate effect on the population are discussed. It was not possible to cause a reversal of the population writhin a vivar suspended in sheep, but since the prey of Polyplastron still existed and since the reverse change was seen to occur in cattle, this problem still remains unsolved. There was also some evidence of antagonism bet ween Epidinium and Ophryoscolex. I N 1 R O l > U C T J O NPrevious studies have shown that when mixtures of rumen ciliate populations from different animals are introduced into the rumens of ciliate-free sheep or cattle certain species often become dominant (Eadie, 1962h). The present work extends these observations and in particular is concerned with the relation between Polyplastron multivesiculatun~ (Dogiel & Federowa) and other rumen ciliates. Investigations have also been made, incidental to the above studies, of the time taken to establish Op/lyrOscolex tricovonatus (Dogiel) in ruminants o f different species, extending previous work on the establishment of rumen ciliate populations (Eadie, 1962 a).The problems were investigated by the use of inoculations of chosen ciliate populations to lambs, kids and a calf; an in vivo method previously discussed by Eadie ( I 962 a, b). In addition a modification of the ' vivar ' technique described by Fina et al. (1962), when used in sheep, proved to be extremely useful. As discussed earlier (Eadie, I 962 b) certain changes of protozoal population in lambs were irreversible, but with the aid of vivar chambers, stages of population changes could be repeatedly observed and could be compared with those seen in the animal.

The Metabolism of Starch, Glucose, Amino Acids, Purines, Pyrimidines and Bacteria by Three & Epidinium spp. Isolated from the Rumen

“…are important members of the B-type of rumen population (Eadie, 1962(Eadie, , 1967)~ especially in New Zealand cows (Clarke, 1964), there have been few studies on their metabolism. Oxford (1959) found that an Epidinium sp.…”

Predação e canibalismo entre protozoários ciliados (Ciliophora: Entodiniomorphida: Ophryoscolecidae) no rúmen de ovinos (Ovis aries)

“…A literatura relata a existência de canibalismo entre organismos da espécie P. multivesiculatum (EADIE 1967). Tal comportamento pode decorrer de mecanismos de competição intraespecífica ou quando outras fontes de alimento encontrem-se em escassez, como por exemplo, quando o hospedeiro passa por um período prolongado de restrição alimentar (EADIE 1967).…”

“…Tal comportamento pode decorrer de mecanismos de competição intraespecífica ou quando outras fontes de alimento encontrem-se em escassez, como por exemplo, quando o hospedeiro passa por um período prolongado de restrição alimentar (EADIE 1967). No presente estudo, o canibalismo foi registrado, pela primeira vez, entre indivíduos da espécie E. bubali.…”

“…Segundo EADIE (1967), o antagonismo entre espécies de protozoários ciliados, pode acarretar predação interespecífica. Um exemplo conhecido deste tipo de interação é a atividade predatória de Polyplastron multivesiculatum (Dogiel & Fedorowa, 1925) sobre espécies de Epidinium Crawley, 1923 e de Eudiplodinium maggii (Fiorentini, 1889), sendo que nestes casos a predação é claramente não acidental, visto que pode levar à completa remoção das populações que constituem as presas (EADIE 1962a,b, 1967, IMAI et al 1979.…”

“…Relatos de canibalismo entre protozoários ciliados no rúmen são ainda mais escassos que os de predação, sendo conhecido entre indivíduos de P. multivesiculatum (EADIE 1967). Nestes casos, a predação pode ocasionar alterações na densidade e na composição das populações de protozoários, variações no tamanho celular e no tempo de geração de novos organismos, além do desenvolvimento de polimorfismo, especialmente nas espécies que se constituem em presas (EADIE 1962a,b, 1967, WILLIAMS & COLEMAN 1992.…”