In addition to the bacteria in the rumen there are many larger (5–250/mm long) organisms which at various times have been designated protozoa Of these the ‘ovals’ (Quin’s and Eadie’s) are now known to be large bacteria (Orpin, 1976) and the ‘flagellates’ Neocallimastix frontalis, Piromonas communis and Sphaeromonas communis are the zoospores of phycomycete fungi (Orpin, 1977a, b) There are genuine flagellates in the rumen, eg Trichomonas spp, Monoceromonas sp and Chilomastix sp, but almost nothing is known about their metabolism (Jensen and Hammon, 1964) The largest, most obvious and most important protozoa are the ciliates, of which there are two groups both in the subclass Trichostomatia The so called ‘holotrich’ protozoa belong to the order Vestibuliferida and the entodiniomorphs to the order Entodiniomorphida, suborder Entodiniomorphina and family Ophryoscolecidae As the properties and metabolism of these two protozoal groups are different, they will be considered separately below

The Rumen Protozoa

Chemical factors involved in ruminal fiber digestion.

Publisher Summary This chapter discusses the direct effects of increase in the global atmospheric CO 2 concentration on natural and commercial temperate trees and forests. The aim of this chapter is to assess what is known of these relationships in trees, and to predict the consequences of an increase in CO 2 on temperate zone forests. Information concerning the reaction of trees and forests to increase in the atmospheric CO 2 concentration is particularly important. The total amount of carbon stored in terrestrial ecosystems has diminished over recent centuries as a result of anthropogenic actions, especially forestry clearance. On a global scale, this further reduction in area of forest will both exacerbate the rise of CO 2 in the atmosphere through oxidation of wood and wood products, and reduce the sink strength for CO 2 . . Because of the complexity of forest ecosystems, there may be many consequences of long-term changes in the rates of carbon gain and water loss by trees and stands. The four main reasons for being concerned about the rise in CO 2 and its effect on trees and forests given here are: the enhancement of biological knowledge about the functioning of tree species of major ecological and economic importance, the impact on the productivity and value of the economic product, the impact on the ecology and environment of woods and forests, and the downstream, socio-economic consequences.

The Direct Effects of Increase in the Global Atmospheric CO2 Concentration on Natural and Commercial Temperate Trees and Forests

Plant responses to atmospheric CO2 enrichment with emphasis on roots and the rhizosphere.

Recent advances in chromatographic identification of CLA isomers, combined with interest in their possible properties in promoting human health (e.g., cancer prevention, decreased atherosclerosis, improved immune response) and animal performance (e.g., body composition, regulation of milk fat synthesis, milk production), has renewed interest in biohydrogenation and its regulation in the rumen. Conventional pathways of biohydrogenation traditionally ignored minor fatty acid intermediates, which led to the persistence of oversimplified pathways over the decades. Recent work is now being directed toward accounting for all possible trans-18:1 and CLA products formed, including the discovery of novel bioactive intermediates. Modern microbial genetics and molecular phylogenetic techniques for identifying and classifying microorganisms by their small-subunit rRNA gene sequences have advanced knowledge of the role and contribution of specific microbial species in the process of biohydrogenation. With new insights into the pathways of biohydrogenation now available, several attempts have been made at modeling the pathway to predict ruminal flows of unsaturated fatty acids and biohydrogenation intermediates across a range of ruminal conditions. After a brief historical account of major past accomplishments documenting biohydrogenation, this review summarizes recent advances in 4 major areas of biohydrogenation: the microorganisms involved, identification of intermediates, the biochemistry of key enzymes, and the development and testing of mathematical models to predict biohydrogenation outcomes.

http://webpages.icav.up.pt/PTDC/CVT/122245/2010/02.pdf

Board-invited review: Recent advances in biohydrogenation of unsaturated fatty acids within the rumen microbial ecosystem.

A survey of the components of the rumen ciliate population in a series of adult sheep, raised in the Faculty of Agriculture, University of Alexandria, has shown that a mixture of Entodinium, Isotricha, Ophryoscolex, Diplodinium, and Polyplastron species was found in the rumen contents of Egyptian sheep; no Epidinium and a negligible number of Dasytricha ruminantium were also observed. The microbial population, reducing sugars, ammonia, volatile fatty acids (VFA) production, and growth rate of 14 lambs inoculated with whole rumen contents from a mature sheep were compared over a 6-month period with those of 13 lambs maintained under the same conditions, except that they were strictly isolated from other ruminants. Certain large oval organisms and large numbers of flagellates and Oscillospira were frequently observed in the rumen contents of the isolated lambs. The reducing sugars, ammonia, and VFA levels, measured before and at intervals after feeding, in the inoculated lambs showed a pronounced rise above the values found in the ciliate-free animals. The propionic acid-acetic acid ratio in the rumen contents of the faunated lambs was considerably higher than in the nonfaunated controls. The inoculated lambs grew faster than the isolated lambs. Differences in weight gain which ranged from 15 to 17% were statistically significant. The inoculated animals impressed the observers by their good appearance which was superior to that of the ciliate-free lambs. It was, therefore, concluded that the rumen ciliate protozoa are essential for the metabolism and growth of young lambs.

https://aem.asm.org/content/aem/12/4/384.full.pdf

Effect of absence of ciliate protozoa from the rumen on microbial activity and growth of lambs.

1. Ten successive trials with two Rahmany adult ewes were carried out with the aim of comparing the nutritive values of the nitrogenous constituents of some concentrates used in Egypt as supplements in summer rations (decorticated cottonseed cake, linseed-oil meal and beans (Vicia faba)) and of animal proteins (meat meal, fish meal and casein) and of barseem (Trifolium alexandrinum). Wheat straw was employed as the main roughage in the ration. Nitrogen intake for all supplements was 10·16 g./day.2. Apparent digestion coefficients for crude protein were estimated. Casein had the highest digestibility coefficient while meat meal was the least digestible.3. Nitrogen retention and ruminal ammonia curves are given for each period. Only three proteins, namely, barseem, cottonseed cake and linseed meal gave positive nitrogen balance at the critical level of nitrogen intake used throughout the trials. Fish meal improved nitrogen retention significantly. Meat meal and beans did not improve nitrogen retention. The addition of 70 g. starch to beans improved nitrogen retention significantly.

Studies on the nutritive value of some common Egyptian feedingstuffs. I. Nitrogen retention and ruminal ammonia curves

1. The levels of blood reducing sugars, haemoglobin, protein N, NPN, ammonia N, and urea N in addition to the nitrogen retention and digestibility coefficients of food constituents, were studied in lambs with and without ciliate protozoa. 2. The inoculated lambs have higher blood haemoglobin, protein N, and lower reducing sugars, ammonia N, and urea N values than those of the uninoculated lambs.

Effect of presence or absence of rumen ciliate protozoa on some blood components, nitrogen retention, and digestibility of food constituents in lambs.

Effect of early establishment of ciliate protozoa in the rumen on microbial activity and growth of early weaned buffalo calves.

A protein index for animal feeds is suggested as a basis for the criteria relating nutritive value to chemical composition. The feeds were classified into four main groups: legumes, non-legumes, straws and concentrates. The regression equations for predicting the nutritive value gave a reasonable level of accuracy (0·18–14·74% error). Higher levels of accuracy were attained employing regression equations formulated for more homogenous feed subgroups classified according to their protein and fibre contents. The percentage error resulting from the use of the specific equations was found to range between zero and 9·88.

K. El-Shazly

Papers

Effect of absence of ciliate protozoa from the rumen on microbial activity and growth of lambs.

Studies on the nutritive value of some common Egyptian feedingstuffs. I. Nitrogen retention and ruminal ammonia curves

Effect of presence or absence of rumen ciliate protozoa on some blood components, nitrogen retention, and digestibility of food constituents in lambs.

Effect of early establishment of ciliate protozoa in the rumen on microbial activity and growth of early weaned buffalo calves.

The prediction of the nutritive value of animal feeds from chemical analyses.