Microbial protein metabolism in the monogastric gastrointestinal tract: a review

Dietary and endogenous protein that become available for the microbiota in the hindgut can be metabolized via different routes. They can become building blocks for the microbial cells or enter different catabolic pathways. Protein degradation via fermentation pathways is seen as a non-preferred route as it results in the formation and release of metabolites that can interfere with biological systems in the host and can have deleterious outcomes. Reducing protein fermentation and guiding the metabolism towards less toxic end-products might be possible targets for improving host health. To do so, more knowledge on factors manipulating the process of microbial protein metabolism, including on substrate availability, microbial composition and segmental differences in the hindgut, is required.

Volatile fatty acids concentration and efficiency of microbial protein synthesis of concentrate cassava peel diet with different levels of protein sources

This study was conducted to evaluate the effects of different levels of protein sources in a concentrate cassava peel diet on volatile fatty acid (VFA) concentration and efficiency of microbial protein synthesis (EMPS) by in vitro method. The five diet treatments in this study consisted of cassava meal (CM), cassava peel (CP), cassava leaves (CL) and moringa leaves (ML) with the proportion applied were T1=CM70% + CP20% + CL5% + ML5%; T2=CM60% + CP20% + CL10% + ML10%; T3=CM50% + CP20% + CL15% + ML15%; T4=CM40% + CP20% + CL20% + ML20%; T5=CM30% + CP20% + CL25% + ML25%. The experiment used a randomized block design with five treatments and three replications. The results showed that increasing the level of protein sources in the ration tended to increase the value of total VFA, acetate, propionate, CO2, and CH4 in which T3 had the highest values. However, the effect of treatments were significant in EMPS value (P<0.01). It was concluded that increasing levels of cassava and moringa leaves in the concentrate cassava peel diet tended to increase the value of total VFA, acetate, propionate, butyrate, CO2, and CH4 which led to a significant increase in EMPS values.

Effect of urea coating by chitosan on the dynamics of ammonia concentration and rumen fermentation in vitro

The aim of this study was to determine the effect of coating urea by chitosan at graded levels on ammonia concentration and rumen fermentation in vitro. This study used Factorial Randomized Complete Block Design (RCBD) to test ammonia parameter and Randomized Complete Block Design (RCBD) for pH, microbial protein synthesis, dry matter and organic matter digestibility, and Volatile Fatty Acid (VFA). The treatments tested were: P0 = addition non coating urea 1%; P1 = coating urea by chitosan 1%; P2 = coating urea by chitosan 2%; P3 = coating urea by chitosan 3%. The data obtained were analysed by using ANOVA and continued with Tukey HSD test with SPSS version 25. The results of this study showed that the coating of urea chitosan had no significant effect on pH, dry matter and organic matter digestibility, microbial protein synthesis, and amonia concentration in the rumen. However, it significantly reduced (P <0.05) total VFA concentration. It can be concluded that the application of urea coating by chitosan does not affect on the degradation of urea in the rumen.

Ruminal Microbiome Manipulation to Improve Fermentation Efficiency in Ruminants

The rumen is an integrated dynamic microbial ecosystem composed of enormous populations of bacteria, protozoa, fungi, archaea, and bacteriophages. These microbes ferment feed organic matter consumed by ruminants to produce beneficial products such as microbial biomass and short-chain fatty acids, which form the major metabolic fuels for ruminants. The fermentation process also involves inefficient end product formation for both host animals and the environment, such as ammonia, methane, and carbon dioxide production. In typical conditions of ruminal fermentation, microbiota does not produce an optimal mixture of enzymes to maximize plant cell wall degradation or synthesize maximum microbial protein. Well-functioning rumen can be achieved through microbial manipulation by alteration of rumen microbiome composition to enhance specific beneficial fermentation pathways while minimizing or altering inefficient fermentation pathways. Therefore, manipulating ruminal fermentation is useful to improve feed conversion efficiency, animal productivity, and product quality. Understanding rumen microbial diversity and dynamics is crucial to maximize animal production efficiency and mitigate the emission of greenhouse gases from ruminants. This chapter discusses genetic and nongenetic rumen manipulation methods to achieve better rumen microbial fermentation including improvement of fibrolytic activity, inhibition of methanogenesis, prevention of acidosis, and balancing rumen ammonia concentration for optimal microbial protein synthesis.

Kecernaan, fermentabilitas dan produksi protein ruminal pelepah sawit yang difermentasi dengan isolat mikrobia rumen kerbau secara in vitro

<p class="MDPI17abstract"><strong>Objective: </strong>The study aimed investigated effect of microbial isolate levels and fermentation time on fermentability regarding ammonia (NH₃) production, volatile fatty acids (VFA) and microbial protein production, dry matter digestibility and organic matter digestibility <em>in vitro</em>.</p><p class="MDPI17abstract"><strong>Methods: </strong>The experiment was conducted at the Laboratory of Nutrition and Feed Science, Faculty of Animal and Agricultural Sciences, Universitas Diponegoro. <em>In vitro</em> experiment was performed using a completely randomized design with a factorial pattern with 2 factors and 4 replications. The treatments were microbial isolate levels (1 and 3%) and fermentation time (14 and 28 days). The parameters observed included production of NH₃, VFA, microbial protein and total protein as well as the digestibility of dry matter and organic matter. The data were analyzed based on analysis of variance and if there was a significant effect the data were further analyzed with Duncan’s Multiple Range Test.<strong></strong></p><p class="MDPI17abstract"><strong>Results: </strong>The amount of microbial isolate and fermentation time affected rumen ammonia production. On rumen microbial protein content, the amounts of microbial isolate and fermentation time had substantial impact (P&lt;0.05). The isolate level and fermentation time, however, had no interaction effect on VFA production, dry matter digestibility, or organic matter digestibility. The fermentation time influenced (P&lt;0.05) the production of VFA and the digestibility of dry matter, but the isolate level and fermentation time had no effect on total protein production or organic matter digestibility.<strong></strong></p><p><strong>Conclusions: </strong>Processing of palm fronds through fermentation using buffalo rumen cellulolytic microbial isolates increased nutrient values of palm fronds.</p>