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

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.

Effects of sodium butyrate and active Bacillus amyloliquefaciens supplemented to pasteurized waste milk on growth performance and health condition of Holstein dairy calves

The objectives of the present study were to examine the impact of feeding both probiotics and sodium butyrate on calf performance and the economic implication of each treatment. A completely randomized design was used to investigate body weight (BW) gain, feed conversion efficiency and health conditions of Holstein dairy calves fed either pasteurized waste milk (PWM; n = 9) or a non-medicated milk replacer containing sodium butyrate and active probiotic Bacillus amyloliquefaciens (NMR; n = 9) from birth to 60 days of age. Numerically, calves fed PWM consumed more starter feed between days 16 and 45 than calves fed NMR but the difference became smaller by 60 days. Birth weights and colostrum IgG and serum total protein concentrations did not differ (p > 0.05) between the PWM and NMR calves. Calves receiving PWM had slightly greater BW at days 30 and 45, but were similar to that of calves receiving NMR at day 60. No differences were observed between PWM and NMR-calves for BW gains, flank height, hip width and health conditions (p < 0.05). Calves fed NMR had more watery feces but less frequent bouts of coughing than PWM-fed calves. Feed cost was higher (p < 0.001) for PWM-fed calves than NMR-fed calves during the experimental period. Dairy calves receiving NMR fortified with sodium butyrate and Bacillus probiotic could perform as similar as calves receiving PWM, and they had similar economic efficiency during the 60-d study period.

Synergetic action between the rumen microbiota and bovine health

Host-rumen-microbe interactions are essential components of many physiological processes, and therefore can affect ruminant health. Classical knowledge of rumen microbiology is based on culture-dependent methodologies, which only account for 10-20% of the rumen bacterial communities. While, the advancement in DNA sequencing and bioinformatics platforms provide novel approaches to investigate the composition and dynamics of the rumen microbiota. Recent studies demonstrated that the ruminal ecosystem is highly diverse and harbors numerous microbial communities. The composition of these microbial communities are affected by various environmental factors such as nutrition and different management strategies. Disturbance in the microbial ecology of the rumen is associated with the development of various diseases. Despite the flow of recent rumen-based studies, rumen microbiota is still not fully characterized. This review provides an overview of recent efforts to characterize rumen microbiota and its potential role in rumen health and disease. Moreover, the recent effects of dietary interventions and probiotics on rumen microbiota are discussed.

Susceptibility of ruminal bacteria isolated from large and small ruminant to multiple conventional antibiotics

The pivotal aim of the present context was to isolate diversified group of bacteria from the ruminants and to evaluate their antibiogram pattern against 22 antibiotics of 14 different classes. The bacterial isolates from small and large ruminant (sheep, cattle and calves) were isolated from the rumen based on various colonies morphology, and subjected for preliminary antibiotics susceptibility assay using disc diffusion method. The most sensitive isolates (based on zone of inhibition) were selected for determining the minimum inhibitory concentration (MIC) of each antibiotic ranging from 1 to 256 μg/mL. Results revealed the concentration dependent growth inhibitory property of antibiotics a species-specific process. The maximum tolerable concentration (MTC) of each antibiotic was further determined using disc diffusion method, and results exhibited that the tolerance nature of ruminal isolates to antibiotics is a species-specific mechanism. Based on the MIC and MTC values of antibiotics, amikacin, ciprofloxacin, and amoxicilline were observed to be the most potent antibiotics in terms of inhibiting the growth of ruminal isolates. In brief, the findings of the current study showed that despite the overexploitation of antibiotics as additives in the animal's feed, most of the ruminal isolates are sensitive to multiple conventional antibiotics tested. The growth inhibitory trait of antibiotics proves these antimicrobials a propitious agent against the pathogenesis of ruminal isolates in livestock.

Role of dose dependent Escherichia coli as ruminal anti-microflora agent to mitigate biogases production in prickly pear cactus flour based diet

The present investigation was conducted to evaluate the effects of Escherichia coli against the ruminal microflora fermentation activities in the mitigation of CH₄ and CO₂ production as well as ruminal fermentation kinetics by substituting dietary corn grain with prickly pear cactus (PC) flour. Three total mixed PC rations were prepared (/kg DM): 0 g (Control), 75 g (PC75), and 150 g (PC150). Besides, E. coli was supplemented at four different levels (dose): 0, 10, 20, and 40 mg/g DM of substrates. The in vitro rumen GP, CH₄, and CO₂ were estimated to be affected due to various doses of E. coli up to 72 h of incubation. Asymptotic GP, fractional rate of GP, and lag time were influenced significantly (P < .05) in the presence of ration. However, E. coli doses showed minor impact on the rate of GP as well as lag time. The asymptotic CH₄ production was decreased linearly (P = .005) at the ration PC150. E. coli doses reduced the asymptotic CH₄ production at 10 and 20 mg/g DM. The asymptotic CO₂ production was linearly (P < .001) decreased by different levels of PC. The cubic (P = .023) effect of E. coli doses as well as significant (P = .002) ration × E. coli doses impact were reported on asymptotic CO₂ production. The fractional rate of GP was quadratically (P < .05) influenced by PC and E. coli doses. The rations, dose, and rations × E. coli dose interaction had no influence (P > .05) on lag time. In a nutshell, PC flour inclusion in diet has the potentiality to replace the existing conventional feedstuffs for ruminant. Most importantly, revealing the first report, PC flours along with E. coli supplementation at varied doses mitigated the ruminal biogases production. This was as consequence to the antimicrobial impacts of E. coli against ruminal microflora, and that could certainly be a promising approach in order to improve ruminant's diet constituents.

Effect of increasing levels of seven tree species extracts added to a high concentrate diet on in vitro rumen gas output

This study was conducted to investigate the effects of increasing levels of extracts of Byrsonima crassifolia, Celtis pallida, Enterolobium cyclocarpum, Fraxinus excelsior, Ficus trigonata, Phoradendrom brevifolium and Prunus domestica on in vitro gas production (GP) and ruminal fermentation of a high concentrate diet. Plant extracts were prepared at 1 g dry matter (DM)/8 mL of solvent mixture (methanol : ethanol : water, 1:1:8) and added at levels of 0, 0.6, 1.2 and 1.8 mL/g DM of a high concentrate diet. In vitro GP was recorded at 2, 4, 6, 8, 10, 12, 24, 48 and 72 h of incubation. Increasing addition of extracts linearly increased (P < 0.001), the GP24 , GP48 and GP72 (mL/g DM), and linearly decreased (P < 0.001), the discrete GP lag time. Moreover, increasing extract doses linearly increased (P < 0.001) the asymptotic GP and decreased (P < 0.001) the rate of GP. GP6 was not impacted by treatments and GP12 increased linearly (P = 0.01) with increasing addition of extracts. Rumen pH declined linearly (P < 0.05) with increasing doses of extracts added. As no interactions (P > 0.05) occurred between the extracts and doses, it could be conclude that all extracts positively modified rumen fermentation at doses of 1.2 to 1.8 mL extract/g diet DM.