Dynamic role of single‐celled fungi in ruminal microbial ecology and activities

Abstract

Summary In ruminants, high fermentation capacity is necessary to develop more efficient ruminant production systems. Greater level of production depends on the ability of the microbial ecosystem to convert organic matter into precursors of milk and meat. This has led to increased interest by animal nutritionists, biochemists and microbiologists in evaluating different strategies to manipulate the rumen biota to improve animal performance, production efficiency and animal health. One of such strategies is the use of natural feed additives such as single‐celled fungi yeast. The main objectives of using yeasts as natural additives in ruminant diets include; (i) to prevent rumen microflora disorders, (ii) to improve and sustain higher production of milk and meat, (iii) to reduce rumen acidosis and bloat which adversely affect animal health and performance, (iv) to decrease the risk of ruminant‐associated human pathogens and (v) to reduce the excretion of nitrogenous‐based compounds, carbon dioxide and methane. Yeast, a natural feed additive, has the potential to enhance feed degradation by increasing the concentration of volatile fatty acids during fermentation processes. In addition, microbial growth in the rumen is enhanced in the presence of yeast leading to the delivery of a greater amount of microbial protein to the duodenum and high nitrogen retention. Single‐celled fungi yeast has demonstrated its ability to increase fibre digestibility and lower faecal output of organic matter due to improved digestion of organic matter, which subsequently improves animal productivity. Yeast also has the ability to alter the fermentation process in the rumen in a way that reduces methane formation. Furthermore, yeast inclusion in ruminant diets has been reported to decrease toxins absorption such as mycotoxins and promote epithelial cell integrity. This review article provides information on the impact of single‐celled fungi yeast as a feed supplement on ruminal microbiota and its function to improve the health and productive longevity of ruminants.

The Effect of Yeast and Roughage Concentrate Ratio on Ruminal pH and Protozoal Population in Thai Native Beef Cattle

“…However, Ramos et al [ 36 ] reported that the high-concentrate diet reduced the richness and diversity of the rumen microbiota. The total population of protozoa in ruminal fluid normally enhances with the high proportion of concentrate diet [ 3 , 50 ].…”

“…Furthermore, the presence of LY in the rumen increases microbial growth, resulting in increased microbial protein transport to the duodenum. In general, yeast supplementation modifies the rumen microbiome population, resulting in improved VFA production and greater microbial protein synthesis [ 42 , 46 , 50 ]. When cows were fed S. cerevisiae at a rate of 56 g/hd/d, microbial protein synthesis increased by 9.3 percent [ 49 ].…”

Roughage to Concentrate Ratio and Saccharomyces cerevisiae Inclusion Could Modulate Feed Digestion and In Vitro Ruminal Fermentation

“…In contrast, Wang et al [7] found that adding LY to crop straw increased CH 4 and that the elevation of CH 4 production could result in increased fiber degradation under in vitro gas production. Elghandour et al [46] conducted an in vitro experiment and proposed that variations in CH 4 production between yeast cultures could be due to their varying protein, fat, fiber, and other material contents.…”

Addition of Active Dry Yeast Could Enhance Feed Intake and Rumen Bacterial Population While Reducing Protozoa and Methanogen Population in Beef Cattle

“…To develop more effective ruminant production systems, ruminants must have a high fermentation capacity. The ability of the microbial ecology to digest organic substances into milk and meat precursors is required for increased production [1]. Many feed additives, such as direct-fed microorganisms, are employed to promote livestock productivity.…”