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.

Establishment of Rumen Ciliate Protozoa in Cow and Water Buffalo (Bos bubalus L.) Calves Under Late and Early Weaning Systems

This study was conducted to investigate the impacts of exogenous fibrolytic enzymes (Fibrozyme, Alltech inc company, USA) supplementation for 12 weeks on milk production and composition as well as blood metabolites in early lactating dairy cows. Total of 120 multiparous Holstein dairy cows at early lactation (57±4.2 days in milk) were randomly assigned into two groups according to lactation period "stage of lactation" and lactation season. The first group (control, n=60) were fed total mixed ration (TMR) without a supplement of exogenous fibrolytic enzymes. The second group (treatment, n=60) were fed TMR supplemented with a commercial exogenous fibrolytic enzymes at the rate of 15 g/cow/d for 12 weeks. Each group was placed in a shaded pen equipped with free stalls. An exogenous fibrolytic enzymes was added to the TMR at the time of feeding once per day at 10 am. Cows were fed as a group open feed, with free access to water. The results of this experiment on dairy cows showed that there were not significant changes in dry matter intake of lactating dairy cows with or without a supplement of exogenous fibrolytic enzymes at early lactation. Exogenous fibrolytic enzymes supplementd to lactating dairy cows improved (P 0.05) but total protein, globulin and cholesterol were declined (P<0.05) due to fibrozyme inclusion compared to control group of dairy cows. The supplementation of exogenous fibrolytic enzymes to early lactating dairy cows achieved higher net profit by 0.93 US$ per cow than control group. It is concluded that exogenous fibrolytic enzymes supplementation to early lactating dairy cows improved significantly milk production, SNF and energy corrected milk.

https://ccsenet.org/journal/index.php/jas/article/download/26140/16634

Effect of Dietary Supplementation With Fibrolytic Enzymes on the Productive Performance of Early Lactating Dairy Cows

Six mature rams were used in a 6 × 6 latin square experiment. They were put on a high concentrate ad lib. diet. Voluntary food intake was measured on the rams which received the following treatments: control, thiouracil, sodium acetate, thyroxine, sodium acetate plus thiouracil and sodium acetate plus thyroxine. Acetate was infused intraruminally at the level of 6·2 g/kg W 0·75 per day for 4 successive days. Thyroxine was injected subcutaneously at the level of 0·3, 0·6, 0·9 and 0·9 mg/kg W 0·75 /day successively. Thiouracil was given orally as the propionyl derivative at a level of 0·03, 0·06, 0·06 and 0·06 g/kg W 0·75 /day successively. Respiration rate, pulse rate and rectal temperature were measured before and 1 h after dosing. A period of at least 25 days was allowed between the trials. All the results were calculated as feed intake (g dry matter)/kg W 0·75 . Injection of thyroxine, sodium acetate and both together inhibited food intake significantly. Thiouracil showed no significant effect on feed intake but it relieved part of the depression caused by acetate. Pulse rate showed significant differences between treatments but rectal temperature and respiration rate did not change significantly. The results are discussed in the text.

A relationship between thyroid activity, acetate infusion and food intake in rams

Washed suspensions of mixed rumen protozoa readily hydrogenated fatty acids in cottonseed, soya bean and corn oils in addition to free oleic and linoleic acids. Protozoa belonging to the family Ophryoscolecidae appeared to account for almost all the activity of mixed protozoa, protozoa of the family Isotrichidae possessing little or no ability to hydrogenate the added substrates. The hydrogenation of oleic acid was markedly increased by Fe and Mn. The addition of starch cellulose, urea and sodium formate greatly stimulated hydrogenation of oleic acid by rumen protozoa. Glucose, casein, ammonium sulphate, L-cysteine and n-valeric acid had no or little effect on extent of hydrogenation.When suspensions of mixed protozoa were incubated in a buffer solution, an increase in iodine value was observed. The desaturation in the protozoal cells was appreciably increased by DL-methionine and was not influenced by L-cysteine. No desaturation activity by the pure suspensions of Ophryoscolecidae or Isotrichidae was observed.The presence of protozoa in the rumen of sheep greatly increased the levels of saturated fatty acids over those in the ciliate-free animals. The concentrations of saturated fatty acids in the plasma of faunated sheep were significantly higher than those in the same animals after the removal of rumen ciliate protozoa.

Effect of rumen protozoa on dietary lipid in sheep

1. Four in vitro fermentation experiments, in duplicate, were carried out over 24 hr. periods, to estimate the production of v.f.a. and o.a from forages. 2. A new technique for determining the total organic acids produced in the rumen is described. 3. The o.a. produced in the earlier part of the fermentation are considerably higher than the v.f.a. but the difference then diminishes. There is practically no difference in the amounts produced after 24 hr. 4. Highly significant correlations were found between the in vitro production of v.f.a. or o.a. and d.e./kg. d.m., for all the roughages tested. Nonlegumes gave a more highly significant correlation than legumes. 5. Regression equations show that o.a. or v.f.a. were more accurate than in vitro cellulose digestion for predicting the d.e./kg. d.m. of non-legume forages. It is concluded that V.F.A. production in vitro is the best criterion in this respect.

The use of the in vitro fermentation technique to estimate the digestible energy content of some Egyptian forages II. The in vitro production of total volatile fatty acids and organic acids as criteria of energy content

K. El-Shazly

Papers

Establishment of Rumen Ciliate Protozoa in Cow and Water Buffalo (Bos bubalus L.) Calves Under Late and Early Weaning Systems

Effect of Dietary Supplementation With Fibrolytic Enzymes on the Productive Performance of Early Lactating Dairy Cows

A relationship between thyroid activity, acetate infusion and food intake in rams

Effect of rumen protozoa on dietary lipid in sheep

The use of the in vitro fermentation technique to estimate the digestible energy content of some Egyptian forages II. The in vitro production of total volatile fatty acids and organic acids as criteria of energy content