The effects of active dried and killed dried yeast on subacute ruminal acidosis, ruminal fermentation, and nutrient digestibility in beef heifers

Molecular detection of ruminal micro-flora and micro-fauna in Saudi Arabian camels: Effects of season and region

This study investigated and explored the availability of micro-flora and micro-fauna in the ruminal contents of Arabian camel (Camelus dromedarius) from three different regions in Saudi Arabia along with two seasons. Samples were prepared and tested by conventional polymerase chain reaction (PCR). This study confirmed that the bacterial flora were dominating over other microbes. Different results of the availability of each microbe in each region and season were statistically analyzed and discussed. There was no significant effect of season on the micro-flora or micro-fauna however, the location revealed a positive effect with Ruminococcus flavefaciens (p < 0 0.03) in the eastern region. This study was the first to investigate the abundance of micro-flora and micro-fauna in the ruminal contents of camels of Saudi Arabia. This study underscores the significance of camel ruminal micro-flora and micro-fauna abundance, highlighting their correlation with both seasonality and geographic location. This exploration enhances our comprehension of camel rumination and digestion processes. The initial identification of these microbial communities serves as a foundational step, laying the groundwork for future in-depth investigations into camel digestibility and nutritional requirements.

Lactational performance and nutrients digestibility response of dairy buffaloes fed diets supplemented with probiotic (Streptococcus spp.) and fibrolytic enzymes

The current study was conducted to explore the productive performance and health status of lactating buffaloes fed diets supplemented with probiotic and/or fibrolytic enzymes. Forty multiparous lactating Egyptian buffaloes (body weight 451 ± 8.5 kg) were equally assigned to four experimental groups: (1) the first group fed control diet, (2) second experimental group fed control diet plus 4 g of probiotic/kg dry matter (DM) (probiotic), (3) third experimental group fed control diet plus 4 g of fibrolytic enzymes/kg DM (enzymes) and (4) fourth experimental group fed control diet plus 2 g of probiotic + 2 g fibrolytic enzymes/kg DM (Mix), The experiment was extended for 63 days. Nutrients digestibility was estimated, daily milk yield was recorded and milk samples were analyzed for total solids, fat protein, lactose and ash. Blood serum samples were analyzed for glucose, total protein, albumin, urea-N, aspartate transaminase, alanine transaminase and cholesterol concentrations. Results showed that adding probiotic and/or fibrolytic enzymes improved nutrients digestibility (p < 0.05). The probiotic, enzymes and mix groups did not affect (p > 0.05) concentrations of serum total protein, albumin (A), globulin (G), albumin/globulin (A/G) ratio and urea-N concentrations. An improvement in daily milk yield (p < 0.0001) and energy-corrected milk (p = 0.0146) were observed with the probiotic and mix groups compared with the control. In conclusion, this study suggests that supplementing lactating buffaloes' diets with probiotic alone or in combination with fibrolytic enzymes would improve their productive performance without adversely impacting their health.

Immunostimulatory effect of mannan-oligosaccharides supplementation diet in milkfish (Chanos chanos)

The current study was designed to examine the impacts of dietary mannan-oligosaccharides (MOS) on growth, hemato-biochemical changes, digestive-antioxidant enzyme activity, immune response, and disease resistance of milkfish (Chanos chanos) fed diets contained MOS i.e. 1g, 2g, and 3g MOS. The growth parameters were significantly influence in milkfish fed all MOS diets, whereas the feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly influence with 2g or 3g MOS diets. The total protein (TP), globulin (GB), and glucose (GLU) levels, amylase, protease, liver enzymes were found significantly high in fish fed 2g or 3g MOS diets; but, lipase, trypsin, and alkaline phosphatase (ALP) enzymes were increased significantly at 3g MOS diet. All MOS inclusion levels were significantly increased total and Lactobacillus intestinal microflora population. The oxidative enzymes activity as superoxide desmutase (SOD) and catalyze (CAT) were progressively increased with all MOS supplementation diet, but the glutathione peroxidase (GPx) and lactate dehydrogenase (LDH) content were found significantly high in fish fed 2g or 3g MOS diets. Similarly, the reduced glutathione (GSH) and glutathione reductase (GR) contents were observed significantly high level in fish fed 3g MOS diet. The phagocytic (PC) and lysozyme (LYZ) activities were found gradually increase in fish fed increasing level of MOS diets, while the respiratory burst (RB) and malondialdehyde (MDA) activities were seen significant in fish fed 2g and 3g MOS diets. The current research work confirmed that C. chanos fed diets contained 3g kg^-1 MOS recorded better growth performance, digestive-antioxidant, immune response, and disease resistance.

Effect of Tea Saponins on Rumen Microbiota and Rumen Function in Qinchuan Beef Cattle

Antibiotics can promote livestock growth but have side effects, so the search for safe and effective alternatives to antibiotics is urgent. This study aimed to evaluate the effect of supplementing cattle feed with tea saponins on ruminal bacteria and fungi. Sixteen Qinchuan beef cattle with a live body weight of 250 ± 10 kg were divided into four groups (four animals in each group) using a completely randomized experimental design. Four different levels of tea saponins were provided to the Qinchuan cattle as treatments, including 0 g/cattle per day control, CON), 10 g/cattle per day (low-level, LT), 20 g/cattle per day (medium-level, MT) and 30 g/cattle per day (high-level, HT). The pre-feeding period was 10 days and the official period was 80 days in this experiment. After 90 days of feeding, the rumen fluid from sixteen Qinchuan beef cattle was collected using an oral stomach tube for evaluating changes in ruminal microbiota and rumen fermentation parameters. Results indicate that the total VFAs and proportions of propionate in the LT group was significantly higher than that in the CON and HT groups (p < 0.05). For ruminal bacteria, results indicate that the Chao1 index of the MT group was significantly lower than the CON and HT groups (p < 0.05). The phyla Bacteroidetes and Firmicutes were found to be the most abundant in all treatment groups, with the LT group having significantly increased relative abundances of Proteobacteria, Actinobacteria and Ascomycota at the phylum level (p < 0.05). The relative abundance of Bacteroides was found to be relatively lower in the LT, MT and HT treatment groups compared with the CON treatment group at the genus level (p < 0.05). For ruminal fungi, the LT treatment group was found to have higher relative abundances of Saccharomyces and Aspergillus, and lower relative abundances of Succiniclasticum and Bacteroides at the at the phylum level (p < 0.05). Compared with the CON treatment group, a significant increase in the relative abundance of Saccharomyces and Aspergillus were observed in the LT treatment group at the genus level (p < 0.05). PICRUSt analyses identified pathways associated with Xenobiotic biodegradation and metabolism and glycolysisIII to be significantly enriched in the LT and HT treatment groups (p < 0.05). These findings could provide insights on how tea saponins may influence ruminal bacteria and fungi, providing a theoretical basis for replacing antibiotics with tea saponins for promoting growth in cattle.

Effectiveness of Probiotic and Combinations of Probiotic with Prebiotics and Probiotic with Rumenotorics in Experimentally Induced Ruminal Acidosis Sheep

Background

Acidosis is one of the most common rumen diseases characterized by changes in the rumen environment and the circulatory system. Recent alternative trends in rearing small ruminants have led to the use of probiotics, rumenotorics and prebiotics to treat acidosis in animals.

Purpose

This study aimed to evaluate the efficacy of probiotics and the combination of probiotics with prebiotics and probiotics with rumenotorics for the treatment of acidosis in sheep.

Methods

This experimental study was conducted from September 2018 to May 2019. For the therapeutic study, 25 sheep were randomly divided into 5 equal groups. Acidosis was induced by an oral dose of 50 g/kg with wheat flour after a 24 hour fast. Four regimens of therapy were employed: PT probiotics, PPT probiotics with prebiotics; PRT probiotics with rumenotorics and standard ST treatment were adopted. Before and after therapy, laboratory analyses on rumen fluid, serum analysis, physical signs, and hematological changes were conducted.

Results

When probiotics were combined with rumenotorics (PRT), the mean standard deviation of rumen pH at day zero was 4.96±0.837 (PRT). Rumen pH improved from day one today three to 5.92±0.54, 6.30±041 and 6.75±0.34, respectively. The change in rumen pH was statistically significant after treatment on day 3 (p=0.002). The therapeutic regimens of PRT had improved heart rate and respiratory rate after treatment and the change was statistically significant (p=0.006 and p=0.000) compared to the control group. The PCV of the PRT treated sheep was also improved.

Conclusion

Probiotics with rumenotorics were the most successful therapeutic regimen for the treatment of ruminal acidosis in sheep. Therefore, the use of probiotics with rumenotorics is the promising alternative for the treatment of acidosis.

Effects of substituting agro-industrial by-products for soybean meal on beef cattle feed utilization and rumen fermentation

The purpose of the present investigation was to detect the effect of replacement of soybean meal (SBM) with citric waste fermented yeast waste (CWYW) as an alternative protein source of portentous substances in a concentrate mixture diet of beef cattle on intake, digestibility, ruminal fermentation, plasma urea-nitrogen, energy partitioning, and nitrogen balance. Four Thai-native beef bulls (170 ± 10.0 kg of initial body weight) were randomly allocated to a 4 × 4 Latin square design. The dietary treatments were four levels of CWYW replacing SBM in a concentrated diet at ratios of 0, 33, 67, and 100%. SBM was added to the concentrate diet at a dose of 150 g/kg DM. All cattle were offered ad libitum rice straw and the concentrate diet at 5 g/kg of body weight. The study was composed of four periods, each lasting for 21 days. The findings demonstrated that there was no difference in total dry matter intake, nutritional intake, or digestibility between treatments (p > 0.05). When CWYW replaced SBM at 100% after 4 h of feeding, ruminal pH, ammonia nitrogen, plasma urea nitrogen, and bacterial population were highest (p < 0.05). Volatile fatty acids and energy partitioning were not different (p > 0.05) among dietary treatments. Urinary nitrogen excretion was greatest (p < 0.05) for cattle fed CWYW to replace SBM at 100% of the concentrate. However, nitrogen absorption and retention for Thai-native cattle were similar (p > 0.05) among treatments. In conclusion, CWYW may be utilized as a substitute for SBM as a source of protein in Thai-native beef cattle without having an adverse impact on feed utilization, rumen fermentation characteristics, or blood metabolites.

Bioconversion of agro-industrial residues as a protein source supplementation for multiparous Holstein Thai crossbreed cows

The purpose of this field study was to compare the effects of top-dressing tropical lactating cows with soybean meal (SBM) or citric waste fermented yeast waste (CWYW) on intake, digestibility, ruminal fermentation, blood metabolites, purine derivatives, milk production, and economic return. Sixteen mid-lactation Thai crossbreeds, Holstein Friesian (16.7 ± 0.30 kg/day milk yield and 490 ± 40.0 kg of initial body weight) were randomly allocated to two treatments in a completed randomized design: SBM as control (n = 8) or CWYW (n = 8). The feeding trial lasted for 60 days plus 21 days for treatment adaptation. The results showed that total dry matter intake, nutrient intake, and digestibility did not (p>0.05) differ between SBM and CWYW top-dressing. Ruminal pH and the protozoal population did not (p>0.05) differ between SBM and CWYW top-dressing. After 4 hours of feeding, CWYW top-dressing showed greater ammonia nitrogen, plasma urea nitrogen, and bacterial population compared with the top-dressing of SBM. Volatile fatty acids and purine derivatives were not different (p>0.05) between SBM and CWYW top-dressing. For milk urea nitrogen, there was a greater (p<0.05) and somatic cell count was lower (p<0.05) for cows fed the CWYW top-dress compared to cows fed the SBM top-dress. The cost of the top-dress and total feed cost were less (p<0.05) for CWYW compared to SBM top-dressing, at 0.59 vs 1.16 US dollars/cow/day and 4.14 vs 4.75 US dollars/cow/day, respectively. In conclusion, CWYW could be used as an alternative protein source to SBM without having a negative impact on tropical lactating cows.

Effects of corn distillers grains with yeast bodies and manipulation of dietary cation and anion difference on production, nutrient digestibility, and gas emissions from manure in lactating cows

In a randomized complete block design, 40 lactating Holstein cows (average 98 d in milk and 41 kg/d of milk yield) were randomly assigned to 1 of 4 diets: (1) containing soybean meal as the major protein supplement (CON diet); (2) CON diet with high-protein dried corn distillers grains at 20% on a dry matter (DM) basis by replacing mainly soybean meal (DG diet); (3) DG diet except that high-protein dried corn distillers grains with yeast bodies (extracted after corn ethanol production) was used (DGY diet); or (4) DG diet supplemented with sodium bicarbonate and potassium carbonate to elevate the dietary cation and anion difference (DCAD; DG-DCAD diet). The DCAD of CON, DG, DGY, and DG-DCAD were 185, 62, 67, and 187 mEq/kg of DM, respectively. The experiment began with a 10-d covariate period and then cows were fed the experimental diets for 5 wk (2-wk diet adaptation and 3-wk data collection periods). Dry matter intake and milk yield were measured daily, and spot urine and fecal samples were collected in the last week of the experiment to measure nutrient digestibility; N, S, and P utilization and excretion; and in vitro NH₃ and H₂S emissions from manure. All data were analyzed using the MIXED procedure of SAS (random effect: block; fixed effects: diets, repeated week, and interactions). During data collection, DM intake was not different among treatment groups, but milk yield tended to be lower (42.4 vs. 39.9 kg/d) for DG, DGY, and DG-DCAD versus CON, which could have been caused by decreases in organic matter and neutral detergent fiber digestibility. Milk protein yield tended to be lower (1.33 vs. 1.24 kg/d) for DG, DGY, and DG-DCAD versus CON. Milk fat yield was lower (1.26 vs. 1.55 kg/d) for DG and DGY versus CON, but that for DG-DCAD (1.43 kg/d) did not differ from CON. Similarly, energy-corrected milk was lower (38.0 vs. 43.3 kg/d) for cows on DG and DGY versus those on CON, but it did not differ between DG-DCAD (40.7 kg/d) and CON. Urinary and fecal N excretion were greater for DG, DGY, and DG-DCAD compared with CON due to greater dietary crude protein content and N intake. However, NH₃ emissions did not differ across treatments. Intakes of dietary P and S were greater for DG, DGY, and DG-DCAD, resulting in greater excretion of those in manure and greater H₂S emissions from manure compared with CON. These data suggest that the negative effects of feeding distillers grains on production of lactating cows can be partly explained by a decrease in nutrient digestibility (milk yield) and excessive anion load (milk fat). The milk fat response to DG-DCAD suggests that milk fat depression observed with a diet with high content of distillers grains can be partially alleviated by supplementation of cations. In the current study, we observed no beneficial effects of DG containing yeast bodies.

Role of probiotics in ruminant nutrition as natural modulators of health and productivity of animals in tropical countries: an overview

Given the ever-growing population in the developing countries located in the tropics of Asia, Africa, South America, and the Caribbean, the demand for products of animal origin has increased. Probiotics have proven to be a substantial substitute for antibiotics used in the animal diet and thus gained popularity. Probiotics are live and non-pathogenic microbes commercially utilized as modulators of gut microflora, hence exerting advantageous effects on the health and productivity of animals in tropical countries. Probiotics are mainly derived from a few bacterial (Lactobacillus, Enterococcus, Streptococcus, Propionibacterium, and Prevotella bryantii) and yeast (Saccharomyces and Aspergillus) species. Numerous studies in tropical animals revealed that probiotic supplementation in a ruminant diet improves the growth of beneficial rumen microbes, thus enhancing nutrient intake and digestibility, milk production, and reproductive and feed efficiency, along with immunomodulation. Furthermore, probiotic applications have proven to minimize adverse environmental consequences, including reduced methane emissions from ruminants' anaerobic fermentation of tropical feedstuffs. However, obtained results were inconsistent due to sources of probiotics, probiotic stability during storage and feeding, dose, feeding frequency, and animal factors including age, health, and nutritional status of the host. Furthermore, the mechanism of action of probiotics by which they exhibit beneficial effects is still not clear. Thus, more definitive research is needed to select the most effective strains of probiotics and their cost-benefit analysis. In this review article, we have briefly explained the impact of feeding probiotics on nutrient intake, digestibility, reproduction, growth efficiency, productivity, and health status of tropical ruminant animals.

Fluorescence activated cell sorting and fermentation analysis to study rumen microbiome responses to administered live microbials and yeast cell wall derived prebiotics

Rapid dietary changes, such as switching from high-forage to high-grain diets, can modify the rumen microbiome and initiate gastrointestinal distress, such as bloating. In such cases, feed additives, including prebiotics and live microbials, can be used to mitigate these negative consequences. Bio-Mos® is a carbohydrate-based prebiotic derived from yeast cells that is reported to increase livestock performance. Here, the responses of rumen bacterial cells to Bio-Mos® were quantified, sorted by flow cytometry using fluorescently-labeled yeast mannan, and taxonomically characterized using fluorescence in situ hybridization and 16S rRNA sequencing. Further, to evaluate the effects of bovine-adapted Bacteroides thetaiotaomicron administration as a live microbial with and without Bio-Mos® supplementation, we analyzed microbial fermentation products, changes to carbohydrate profiles, and shifts in microbial composition of an in vitro rumen community. Bio-Mos® was shown to be an effective prebiotic that significantly altered microbial diversity, composition, and fermentation; while addition of B. thetaiotaomicron had no effect on community composition and resulted in fewer significant changes to microbial fermentation. When combined with Bio-Mos®, there were notable, although not significant, changes to major bacterial taxa, along with increased significant changes in fermentation end products. These data suggest a synergistic effect is elicited by combining Bio-Mos® and B. thetaiotaomicron. This protocol provides a new in vitro methodology that could be extended to evaluate prebiotics and probiotics in more complex artificial rumen systems and live animals.

Changed Rumen Fermentation, Blood Parameters, and Microbial Population in Fattening Steers Receiving a High Concentrate Diet with Saccharomyces cerevisiae Improve Growth Performance

The effect of dry yeast (DY) (Saccharomyces cerevisiae) supplementation in a high-concentrate diet was evaluated for rumen fermentation, blood parameters, microbial populations, and growth performance in fattening steers. Sixteen crossbred steers (Charolais x American Brahman) at 375 ± 25 kg live weight were divided into four groups that received DY supplementation at 0, 5, 10, and 15 g/hd/d using a completely randomized block design. Basal diets were fed as a total mixed ration (roughage to concentrate ratio of 30:70). Results showed that supplementation with DY improved dry matter (DM) intake and digestibility of organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) (p < 0.05), but DM and crude protein (CP) were similar among treatments (p > 0.05). Ruminal pH (>6.0) of fattening steer remained stable (p > 0.05), and pH was maintained at or above 6.0 with DY. The concentration of propionic acid (C₃) increased (p < 0.05) with 10 and 15 g/hd/d DY supplementation, while acetic acid (C₂) and butyric acid (C₄) decreased. Methane (CH₄) production in the rumen decreased as DY increased (p < 0.05). Fibrobacter succinogenes and Ruminococcus flavefaciens populations increased (p < 0.05), whereas protozoal and methanogen populations decreased with DY addition at 10 and 15 g/hd/d, while Ruminococcus albus did not change (p > 0.05) among the treatments. Adding DY at 10 and 15 g/hd/d improved growth performance. Thus, the addition of DY to fattening steers with a high concentrate diet improved feed intake, nutrient digestibility, rumen ecology, and growth performance, while mitigating ruminal methane production.

The impacts of a fibrolytic enzyme additive on digestibility and performance in the grower and early finisher period, and supplemental Saccharomyces cerevisiae on performance and rumen health in the late finisher period for feedlot cattle

Two experiments were conducted to determine the effects of a fibrolytic enzyme pretreatment on growth performance, apparent total tract digestibility, and ruminal pH throughout the grower and early finisher period (exp. 1), and to examine the impact of Saccharomyces cerevisiae supplementation on intake, performance, and indicators of gut health in the late finisher period (exp. 2). A total of 54 steers were randomly assigned to a subgroup determining experimental treatment groups. In exp. 1, steers were randomized to control (CON1; no enzyme) or enzyme [ENZ; 0.75 mL·kg−1 dry matter (DM) of feed] dietary treatments. Digestibility was improved (P ≤ 0.05) in ENZ steers for DM, crude protein, net energy for gain, and sugars but did not affect (P ≥ 0.12) dry matter intake (DMI), average daily gain (ADG), or reticulo-ruminal pH. In exp. 2, the treatments were control (CON2; no yeast) or yeast (YST; 3.0 g·animal−1 daily) supplemented diets. Rumen papillae were collected for mRNA expression of gut barrier function (OCLN, CLDN, ZO1, and ZO2) and immune response (TLR2, TLR4, and FCAR) genes and histological measurements. Yeast supplementation decreased (P < 0.001) DMI by 31%, reduced variation in DMI, and improved feed conversion ratios but did not impact rumen health mRNA expression or histology measures (P ≥ 0.07). Overall, enzyme supplementation improved the digestibility of some nutrients in the grower period, and yeast supplementation improved feed efficiency, without impacting growth performance or gut health.

Utilization of Yeast Waste Fermented Citric Waste as a Protein Source to Replace Soybean Meal and Various Roughage to Concentrate Ratios on In Vitro Rumen Fermentation, Gas Kinetic, and Feed Digestion

The objective of this study was to determine the application of citric waste fermented yeast waste (CWYW) obtained from an agro-industrial by-product as a protein source to replace soybean meal (SBM) in a concentrate diet. We also determined the effect of various roughage to concentrate ratios (R:C) on the gas production kinetics, ruminal characteristics, and in vitro digestibility using an in vitro gas production technique. The experiment design was a 3 × 5 factorial design arranged in a completely randomized design (CRD), with three replicates. There were three R:C ratios (60:40, 50:50, and 40:60) and five replacing SBM with CWYW (SBM:CWYW) ratios (100:0, 75:25, 50:50, 25:75, and 0:100). The CWYW product’s crude protein (CP) content was 535 g/kg dry matter (DM). There was no interaction effect between R:C ratios and SBM:CWYW ratios for all parameters observed (p > 0.05). The SBM:CWYW ratio did not affect the kinetics and the cumulative amount of gas. However, the gas potential extent and cumulative production of gas were increased with the R:C ratio of 40:60, and the values were about 74.9 and 75.0 mL/0.5 g, respectively (p < 0.01). The replacement of SBM by CWYW at up to 75% did not alter in vitro dry matter digestibility (IVDMD), but 100% CWYW replacement significantly reduced (p < 0.05) IVDMD at 24 h of incubation and the mean value. In addition, IVDMD at 12 h and 24 h of incubation and the mean value were significantly increased with the R:C ratio of 40:60 (p < 0.01). The SBM:CWYW ratio did not change the ruminal pH and population of protozoa (p > 0.05). The ruminal pH was reduced at the R:C ratio of 40:60 (p < 0.01), whereas the protozoal population at 4 h was increased (p < 0.05). The SBM:CWYW ratio did not impact the in vitro volatile fatty acid (VFA) profile (p > 0.05). However, the total VFA, and propionate (C3) concentration were significantly increased (p < 0.01) by the R:C ratio of 40:60. In conclusion, the replacement of SBM by 75% CWYW did not show any negative impact on parameters observed, and the R:C ratio of 40:60 enhanced the gas kinetics, digestibility, VFA, and C3 concentration.

Effects of dry yeast supplementation on growth performance, rumen fermentation characteristics, slaughter performance and microbial communities in beef cattle

This study aimed to investigate the effects of active dry yeast (ADY) on growth performance, rumen microbial composition and carcass performance of beef cattle. Thirty-two finishing beef cattle (yak ♂ × cattle-yaks ♀), with an average body weight of 110 ± 12.85 kg, were randomly assigned to one of four treatments: the low plane of nutrition group (control), low plane of nutrition group + ADY 2 g/head daily (ADY2), low plane of nutrition group + ADY 4 g/head daily (ADY4) and the high plane of nutrition group (HPN). Supplementation of ADY increased average daily gain compared to the control group. The neutral detergent fiber and acid detergent fiber apparent digestibility in HPN group was greater than that in control group. The propionic acid concentration in the rumen in ADY2, ADY4, and HPN groups was greater than that in control group. The Simpson and Shannon indexes in control and HPN groups were higher than that in ADY4 group. At the phylum level, the relative abundance of Firmicutes in the HPN group was higher than that in ADY4 group. The relative abundance of Ruminococcaceae UCG-002 in ADY4 group was higher than that in control and HPN groups. In conclusion, supplementation ADY 4 g/head daily shift the rumen microbial composition of beef cattle fed low plane of nutrition to a more similar composition with cattle fed with HPN diet and produce the similar carcass weight with HPN diet.HighlightsThe ADY can improve the utilization of nitrogen and decrease the negative impact on the environment in beef cattle.Cattle fed low plane of nutrition diet supplemented with ADY 4 g/head daily increased growth performance.Supplementation ADY 4 g/head daily in low plane of nutrition diet might be produced comparable carcass weight to HPN diet.

Probiotic microorganisms and herbs in ruminant nutrition as natural modulators of health and production efficiency – a review

Probiotics, prebiotics, synbiotics, direct-fed microbials, and herbs may improve the production efficiency in ruminants. The beneficial effect of selected specific microbes on animal health is reflected in protection against pathogens, stimulation of immunological response, increased production capacity, and mitigation of stress effects. Phytobiotic plants used in the nutrition of ruminant animals increase feed palatability. This in turn has a positive effect on feed intake and, consequently, increases production performance. Pectins, terpenes, phenols, saponins, and antibioticlike substances contained in phytobiotics prevent irritation, diarrhea, and increase the activity of digestive enzymes. Thanks to the abundance of biologically active substances such as flavonoids, glycosides, coumarins, carotenoids, polyphenols, etc., phytobiotics exhibit immunostimulatory and antioxidant properties as well. Given such a wide range of effects on health status and production parameters in animals, an attempt was made in this review to compile the current knowledge on the possible application of these natural growth stimulants in ruminant nutrition and to demonstrate their potential benefits and/or risks for breeding these animals.

Identification of a Candidate Starch Utilizing Strain of Prevotella albensis from Bovine Rumen

The inclusion of starch-rich feedstuffs, a common practice in intensive ruminant livestock production systems, can result in ruminal acidosis, a condition that can severely impact animal performance and health. One of the main causes of acidosis is the rapid accumulation of ruminal short chain fatty acids (SCFAs) resulting from the microbial digestion of starch. A greater understanding of ruminal bacterial amylolytic activities is therefore critical to improving mitigation of acidosis. To this end, our manuscript reports the identification of a candidate starch utilizer (OTU SD_Bt-00010) using batch culturing of bovine rumen fluid supplemented with starch. Based on 16S rRNA gene sequencing and metagenomics analysis, SD_Bt-00010 is predicted to be a currently uncharacterized strain of Prevotella albensis. Annotation of de novo assembled contigs from metagenomic data not only identified sequences encoding for α-amylase enzymes, but also revealed the potential to metabolize xylan as an alternative substrate. Metagenomics also predicted that SCFA end products for SD_Bt-00010 would be acetate and formate, and further suggested that this candidate strain may be a lactate utilizer. Together, these results indicate that SD_Bt-00010 is an amylolytic symbiont with beneficial attributes for its ruminant host.

Effect of active dry yeast on lactation performance, methane production, and ruminal fermentation patterns in early-lactating Holstein cows

This study was conducted to examine the effect of active dry yeast (ADY) supplementation on lactation performance, ruminal fermentation patterns, and CH₄ emissions and to determine an optimal ADY dose. Sixty Holstein dairy cows in early lactation (52 ± 1.2 DIM) were used in a randomized complete design. Cows were blocked by parity (2.1 ± 0.2), milk production (35 ± 4.6 kg/d), and body weight (642 ± 53 kg) and assigned to 1 of 4 treatments. Cows were fed ADY at doses of 0, 10, 20, or 30 g/d per head for 91 d, with 84 d for adaptation and 7 d for sampling. Although dry matter intake was not affected by ADY supplementation, the yield of actual milk, 4% fat-corrected milk, milk fat yield, and feed efficiency increased quadratically with increasing ADY supplementation. Yields of milk protein and lactose increased linearly with increasing ADY doses, whereas milk urea nitrogen concentration and somatic cell count decreased quadratically. Ruminal pH and ammonia concentration were not affected by ADY supplementation, whereas ruminal concentration of total volatile fatty acid increased quadratically. Digestibility of dry matter, organic matter, neutral detergent fiber, acid detergent fiber, nonfiber carbohydrate, and crude protein increased quadratically with increasing ADY supplementation. Supplementation of ADY did not affect blood concentration of total protein, triglyceride, aspartate aminotransferase, and alanine aminotransferase, whereas blood urea nitrogen, cholesterol, and nonesterified fatty acid concentrations decreased quadratically with increasing ADY supplementation. Methane production was not affected by ADY supplementation when expressed as grams per day or per kilogram of actual milk yield, dry matter intake, digested organic matter, and digested nonfiber carbohydrate, whereas a trend of linear and quadratic decrease of CH₄ production was observed when expressed as grams per kilogram of fat-corrected milk and digested neutral detergent fiber. In conclusion, feeding ADY to early-lactating cows improved lactation performance by increasing nutrient digestibility. The optimal ADY dose should be 20 g/d per head.

Microbial fermentation of starch- or fibre-rich feeds added with dry or pre-activated Saccharomyces cerevisiae studied in vitro under conditions simulating high-concentrate feeding for ruminants

BACKGROUND

To study if the effect on fermentation of yeasts added in ruminant diets can be improved, the effect of adding dry (DY) or pre-activated (AY) Saccharomyces cerevisiae, compared with unsupplemented rumen fluid (CT), on barley grain or sugar beet pulp was evaluated under in vitro high-concentrate fermentative conditions. Yeasts were pre-activated by culturing aerobically at 30 °C for 24 h.

RESULTS

In Experiment 1, AY showed a higher concentration than DY at 6 h incubation (6.83 versus 5.76 log cfu mL^-1 ; P = 0.007), differences disappearing at 12 h. This was supported by higher gas production with AY, especially on sugar beet pulp. In Experiment 2, incubation pH was 6.24 and 6.31 respectively for barley and sugar beet pulp at 8 h (P < 0.05), but no effect was recorded at 24 h (6.00 and 5.96; P > 0.05). With sugar beet pulp, gas production promoted by AY was the highest (P < 0.05) in the first 8 h of incubation. However, differences with barley were lower and only detected between AY and CT at 12 h (P < 0.05). Total volatile fatty acids (VFAs) concentration at 8 h followed the same trend, but no differences were detected on molar VFAs profile or lactate concentration. Microbial diversity was more affected by the incubation series than by experimental treatments, and inocula including yeasts (AY, DY) did not differ from unsupplemented rumen liquid.

CONCLUSIONS

When pre-activated, the concentration of S. cerevisiae was initially higher and resulted in higher gas volumes, and more on a fibrous (sugar beet pulp) than a starchy (barley) substrate. The response is apparently quantitative, since no major changes were detected on biodiversity or fermentation profile. © 2020 Society of Chemical Industry.

BEEF SPECIES-RUMINANT NUTRITION CACTUS BEEF SYMPOSIUM: Energy and roughage levels in cattle receiving diets and impacts on health, performance, and immune responses1

Transition of newly received feedlot cattle from a forage- to grain-based diet is challenging, and the appropriate roughage level in receiving diets is debatable. Nutritionists must consider the paradox of dietary transition and roughage level to mitigate ruminal acidosis, yet concomitantly low feed intake presents difficulty in achieving nutrient requirements when metabolic demand is increased due to inherent stress and disease challenge during the receiving period. Previous research suggests that performance is improved at the expense of increased morbidity for newly received cattle consuming diets with less roughage and greater starch concentration. The clinical signs of bovine respiratory disease (BRD) and acute acidosis are analogous; therefore, it is probable that acidotic cattle are incorrectly diagnosed with BRD in both research and production settings. Additional research efforts have attempted to elucidate alterations in microbial populations and digestion, physiological response to inflammatory challenge, and immunological response to infectious bovine rhinotracheitis virus challenge in cattle consuming diets of various roughage levels. Furthermore, our understanding of the rumen microbiome is improving rapidly with culture-independent assays, products such as direct-fed microbials are available, and increased availability and use of fibrous byproduct ingredients requires further attention. Beef cattle nutritionists and producers should consider that the health benefit of receiving diets containing greater levels of roughage and lower energy may not compensate for the reduction in performance compared with feeding receiving diets with lower roughage and greater energy.

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 active dried Saccharomyces cerevisiae on ruminal fermentation and bacterial community during the short-term ruminal acidosis challenge model in Holstein calves

We investigated the effects of active dried Saccharomyces cerevisiae (ADSC) on ruminal pH, fermentation, and the fluid bacterial community during the short-term ruminal acidosis challenge. Five rumen-fistulated male Holstein calves (147.0 ± 5.8 kg of body weight; 3.6 ± 0.2 mo of age) were used in a crossover design, and 0 g (control group, n = 5) or 2 g (SC group, n = 5) of ADSC (1 × 10¹⁰ cfu/g) was administered twice daily for 21 consecutive days. Calves were fed a high-forage diet during the first 15 d (d -14 to d 0; prechallenge), a high-grain diet for 2 d (d 1 and 2; ruminal acidosis challenge), and a high-forage diet for 4 d (d 3 to 6; postchallenge). Ruminal pH was measured continuously. Rumen fluid samples were collected once daily (0800 h) on d 0, 3, 4, and 6 and twice daily (0800 and 1100 h) on d 1 and 2. Bacterial DNA was extracted from fluid samples collected on d 0 and 3. The 24-h and 1-h mean ruminal pH was significantly depressed during the ruminal acidosis challenge in each group, although the changes were more severe in the SC group, consistent with a significant increase in lactic acid on d 2 (1100 h) compared with d 0 and a significantly higher proportion of butyric acid on d 2 (1100 h) compared with the control group. Feeding a high-grain diet caused a decrease in bacterial diversity due to high acidity in both groups. The relative abundances of the genus Bifidobacterium and operational taxonomic unit (OTU) 3 (Bifidobacterium species) increased significantly in both groups but were higher in the SC group. Correlation analyses indicated that OTU3 (Bifidobacterium species) were positively correlated with lactic acid concentration and that OTU1 (Prevotella species) and OTU5 (Succinivibrio species) were correlated with the proportion of butyric acid. These results suggest that ADSC supplementation induced the intense decreases in ruminal pH by increased butyric and lactic acid production through a high-grain diet fermentation by rumen fluid bacterial species during the short-term ruminal acidosis challenge in Holstein calves after weaning.

Using ruminally protected and nonprotected active dried yeast as alternatives to antibiotics in finishing beef steers: growth performance, carcass traits, blood metabolites, and fecal Escherichia coli

The objective of this study was to evaluate the effects of supplementing the diet of finishing beef steers with active dried yeast (ADY) in ruminally protected and nonprotected forms on growth performance, carcass traits, and immune response. Seventy-five individually-fed Angus steers (initial body weight (BW) ± SD, 448 ± 8.4 kg) were assigned to a randomized complete design with 5 treatments: 1) control (no monensin, tylosin, or ADY), 2) antibiotics (ANT, 330 mg monensin + 110 mg tylosin·steer-1d-1), 3) ADY (1.5 g·steer-1d-1), 4) encapsulated ADY (EDY; 3 g·steer-1d-1), and 5) a mixture of ADY and EDY (MDY; 1.5 g ADY + 3 g EDY·steer-1d-1). Active dried yeast with 1.7 × 1010 cfu/g was encapsulated in equal amounts of ADY and capsule materials (stearic acid and palm oil). Steers were fed a total mixed ration containing 10% barley silage and 90% barley-based concentrate mix (dry matter [DM] basis). The ANT, ADY, and EDY were top-dressed daily to the diet at feeding. Intake of DM, final BW, averaged daily gain (ADG), and gain-to-feed ratio (G:F) were unaffected by ADY or EDY. Carcass traits including hot carcass weight (HCW), dressing percentage, marbling score and quality grade did not differ among treatments, although fewer severely abscessed livers were observed (P < 0.05) with ADY and MDY compared with the other treatments. Plasma urea N tended (P < 0.10) to be greater in steers fed ANT, ADY, or EDY on day 56 and 112, while glucose remained stable in all treatments except greater (P < 0.02) plasma glucose occurred in steers fed MDY on day 112. Serum nonestrified fatty acid (NEFA) was unaffected by ADY or EDY, but it was greater (P < 0.03) in steers fed ANT compared with control. Plasma haptoglobin (Hp) and serum amyloid A (SAA) were affected by yeast supplementation on day 112, with greater (P < 0. 01) Hp in steers fed ADY, EDY, or MDY and lesser (P < 0.01) SAA in steers fed EDY and MDY than control. Lipopolysaccharide binding protein concentrations were greater (P < 0.01) in steers fed EDY and MDY on day 56. Supplementing with ADY (protected or nonprotected) or ANT had no effect on fecal IgA contents on day 56 and 112. Steers fed yeast (EDY or MDY) tended (P < 0.10) to have fewer fecal Escherichia coli counts than the control and ANT on day 56 and 112. These results indicate that feeding ADY to feedlot cattle may exhibit antipathogenic activity that conferred health and food safety beneficial effects including reduced liver abscess and potentially pathogen excretion, thus yeast may be an alternative to in-feed antibiotics in natural beef cattle production systems.

Use of live yeast and mannan-oligosaccharides in grain-based diets for cattle: Ruminal parameters, nutrient digestibility, and inflammatory response

The objective of this study was to evaluate the effects of diet supplementation with live yeast (Saccharomyces cerevisiae) and mannan-oligosaccharides (MOS) on ruminal parameters, nutrient digestibility, and the inflammatory response in cattle fed grain-based diets. Three Holstein steers (body weight of 497±3 kg) with ruminal and duodenal cannulas were assigned to a 3 × 3 Latin square design. The animals were kept in individual pens and fed a diet containing 5% sugarcane bagasse and 95% concentrate (906.5 g/kg ground corn). Diet treatments were Control (without additive), Yeast (1.5 g/kg DM live yeast Saccharomyces cerevisiae, NCYC 996) and MOS (1.5 g/kg DM MOS, β-glucans and mannan). Dry matter intake, ruminal, intestinal, and total digestibility of nutrients were not affected by the treatments. The ruminal concentration of isobutyric acid increased in animals fed on diets supplemented with Yeast and MOS, whereas isovaleric acid increased with Yeast and decreased with MOS supplementation. Dietary supplementation with Yeast and MOS increased pH and decreased ammonia concentration in the rumen. Lipopolysaccharide (LPS) concentrations in the rumen and duodenal fluid were not influenced by the additives. However, both Yeast and MOS decreased the plasma levels of LPS and serum amyloid A (SAA). In conclusion, when high-concentrate diets fed to beef cattle are supplemented with either Yeast or MOS, ruminal pH is increased, LPS translocation into the blood stream is decreased, and blood SAA concentration is decreased. These factors reduce the inflammation caused by consumption of grain-based diets, and either supplement could be used to improve the rumen environment in beef cattle susceptible to ruminal subacute acidosis.

Impact of strain and dose of live yeast and yeast derivatives on in vitro ruminal fermentation of a high-grain diet at two pH levels

The objective of this study was to determine the effects of live yeast (LY) or yeast derivatives (YD) on gas production (GP), dry matter (DM) disappearance (DMD), fermentation characteristics, and microbial profiles in batch culture. The study was a completely randomized design with a factorial arrangement: 2 media pH × 5 yeasts × 4 dosages. An additional treatment of monensin (Mon) was added as a positive control for each pH level. Media pH was low (5.8) and high (6.5); the yeasts were three LY (LY1-3) and two YD (YD4-5); and doses were 0, 4 × 106, 8 × 106, and 1.6 × 107 cfu mL−1 for LY and 0, 15, 30, and 60 mg bottle−1 for YD. Substrate consisted of 10% silage and 90% concentrate (DM basis) and samples were incubated for 24 h. Media pH of 6.5 vs. 5.8, increased (P < 0.01) GP, DMD, and volatile fatty acid (VFA) concentrations but decreased (P < 0.01) NH3-N concentration and copy numbers of Ruminococcus albus, Ruminococcus flavefaciens, and Selenomonas ruminantium. Increasing dose of LY2 linearly (P < 0.05) increased DMD. Total VFA concentration was greater with LY2 (P < 0.01) than LY3 and YD5 at pH 6.5. Overall, adding yeast products improved (P < 0.05) DMD at pH 5.8, and increased VFA concentration compared with Mon. These results indicate that in vitro GP and DMD of a high-grain diet varied with source and dose of yeast supplementation. Some yeast products have the potential to improve fermentation of feedlot diets when supplemented at appropriate doses.

Inclusion of live yeast and mannan-oligosaccharides in high grain-based diets for sheep: Ruminal parameters, inflammatory response and rumen morphology

The objective of this study was to evaluate the effects of dietary supplementation with live yeast (Saccharomyces cerevisiae), mannan-oligosaccharides and the combination of these additives on the inflammatory response, ruminal parameters and rumen morphology of sheep fed a high grain-based diet. Thirty-Two Dorper x Santa Ines crossbred lambs with an average weight of 24±2 kg were distributed in a completely randomized design. The animals were housed in individual stalls and fed ad libitum. Diet treatments were: Control (without additive); LY (2 g/kg DM of live yeast, Saccharomyces cerevisiae), MOS (2 g/kg DM of mannan-oligosaccharides) and LY+MOS (2 g/kg DM of LY + 2 g/kg DM of MOS). The experiment lasted 42 days. The supplementation with MOS alone and the additives combination resulted in increased ruminal pH (P<0.01), while the total concentrations of short chain fatty acids (SCFA) in the rumen were higher (P<0.05) only in the diets with LY and MOS. Ammonia (NH3) concentration in the rumen decreased (P<0.04) with the additives usage. Diets with LY, MOS and with additives combination reduced (P<0.01) the levels of lipopolysaccharides (LPS) in the plasma with values of 0.46; 0.44 and 0.04 EU/mL, respectively when compared to the control (0.93 EU/mL). MOS and LY+MOS treatments had reduced stratum corneum thickness (P<0.01) in comparison to the control treatment. The total thickness of ruminal epithelium was lower with the addition of MOS in the diet (P<0.03) than with LY additive. The incidence and severity of hepatic abscesses in animals whose diet was supplemented with LY and LY+MOS was lower (P<0.05) than in animals fed the control diet. The use of LY, MOS and LY+MOS in the high-concentrate diets for sheep reduced NH3 concentrations and LPS translocation into the bloodstream. Diets containing MOS and LY+MOS enhanced the health of the ruminal epithelium by reducing the thickness of the stratum corneum, and diets containing LY and LY+MOS decreased the incidence and severity of hepatic abscesses.

Comparison of ruminal fermentation parameters, fatty acid composition and flavour of beef in finishing bulls fed active dry yeast (Saccharomyces cerevisiae) and yeast culture

This study was conducted to compare the effect of active dry yeasts (ADY) and yeast cultures (YC), two typical products of yeast preparations, on ruminal fermentation parameters, and on the fatty acid composition and flavour of beef from finishing bulls fed a high-concentrate diet. Forty-five finishing bulls (mean bodyweight ± s.d.: 505.4 ± 29.1 kg body weight) were allocated to three groups of 15 bulls and assigned randomly to one of three diets, which were CON diet (basal diet), ADY diet (basal diet + Levucell SC) and YC diet (basal diet + Diamond V XP). After 112 days trial, all bulls (mean bodyweight ± s.d.: 591.6 ± 64.2 kg body weight) were slaughtered. The rumen fluid of each animal was collected at slaughter and cross-sectional samples of longissimus lumborum were collected from three treatments at carcass segmentation after a 24-h chill. The result indicated that both ADY and YC supplementation had no significant effect (P > 0.05) on rumen pH, concentration of ammonia-N and total volatile fatty acid compared with CON. ADY had no significant effect (P > 0.05) on percentage of rumen individual fatty acid whereas YC significantly decreased valerate molar percentage (P = 0.008) and increased acetate molar percentage (P = 0.029) and the ratio of acetate to propionate (P = 0.035). In addition, compared with CON, ADY significantly (P = 0.003) increased the concentration of C16:1n7 and significantly (P = 0.012) decreased the concentration of C18:3n6c compared with CON. YC significantly decreased the concentration of C18:3n6c (P = 0.014) compared with CON. However, both ADY and YC had no significant effect (P > 0.05) on other individual fatty acid concentrations, the proportions of saturated fatty acids and monounsaturated fatty acids and nutritionally important values including the ratio of n-6/n-3, polyunsaturated fatty acids/saturated fatty acid and C18:2n6/C:18:3n3. Both ADY and YC significantly improved beef tenderness for cooking method of chaffy dish (P < 0.05) and beef tenderness also tended improve for ADY (P = 0.075) and YC (P = 0.097) when samples were fried. Both ADY and YC did not show improvements in flavour or juiciness compared with CON for either cooking method.

Effects of dietary supplementation of active dried yeast on fecal methanogenic archaea diversity in dairy cows

This study aimed to investigate the effects of dietary supplementation of different dosages of active dried yeast (ADY) on the fecal methanogenic archaea community of dairy cattle. Twelve multiparous, healthy, mid-lactating Holstein dairy cows (body weight: 584 ± 23.2 kg, milk produced: 26.3 ± 1.22 kg/d) were randomly assigned to one of three treatments (control, ADY2, and ADY4) according to body weight with four replicates per treatment. Cows in the control group were fed conventional rations without ADY supplementation, while cows in the ADY2 and ADY4 group were fed rations supplemented with ADY at 2 or 4 g/d/head. Real-time PCR analysis showed the populations of total methanogens in the feces were significantly decreased (P < 0.05) in the ADY4 group compared with control. High-throughput sequencing technology was applied to examine the differences in methanogenic archaea diversity in the feces of the three treatment groups. A total of 155,609 sequences were recovered (a mean of 12,967 sequences per sample) from the twelve fecal samples, which consisted of a number of operational taxonomic units (OTUs) ranging from 1451 to 1,733, were assigned to two phyla, four classes, five orders, five families and six genera. Bioinformatic analyses illustrated that the natural fecal archaeal community of the control group was predominated by Methanobrevibacter (86.9% of the total sequence reads) and Methanocorpusculum (10.4%), while the relative abundance of the remaining four genera were below 1% with Methanosphaera comprising 0.8%, Thermoplasma composing 0.4%, and the relative abundance of Candidatus Nitrososphaera and Halalkalicoccus being close to zero. At the genus level, the relative abundances of Methanocorpusculum and Thermoplasma were increased (P < 0.05) with increasing dosage of ADY. Conversely, the predominant methanogen genus Methanobrevibacter was decreased with ADY dosage (P < 0.05). Dietary supplementation of ADY had no significant effect (P > 0.05) on the abundances of genera unclassified, Candidatus Nitrososphaera, and Halalkalicoccus. In conclusion, supplementation of ADY to the rations of dairy cattle could alter the population sizes and composition of fecal methanogenic archaea in the feces of dairy cattle. The decrease in Methanobrevibacter happened with a commensurate increase in the genera Methanocorpusculum and Thermoplasma.

Effect of disodium/calcium malate or supplementation on growth performance, carcass quality, ruminal fermentation products, and blood metabolites of heifers

The aim of this study was to assess the effects of malate salts and culture on growth performance, carcass quality, ruminal fermentation products, and blood metabolites in heifers raised under southern Europe practical farm conditions. A total of 108 Charolaise cross heifers (214 ± 27.3 kg BW and 6.4 ± 1.1 mo of age) were housed in 18 pens of 6 animals each and used in a 114-d feedlot study. There was a totally randomized experimental design, and 6 pens were assigned to each of the following experimental diets: a control (no supplementation), the control plus 4 g of disodium/calcium malate mixture per kilogram of concentrate (2.12 g malate/kg), and the control plus 0.15 g of CBS 493.94 per kilogram of concentrate (1.5 × 10 cfu/kg). The control diet consisted of wheat-barley-based pelleted concentrate (32% starch, DM basis) and full-length barley straw. Concentrate and straw were fed separately ad libitum (5% orts) in an 88:12 ratio. On Days 0, 56, and 114, ruminal fluid and blood samples were obtained from each heifer between 2 and 2.5 h after the morning feeding by ruminocentesis and tail venipuncture, respectively. Body weight, concentrate ADFI, and G:F were recorded at 28, 56, 84, and 114 d. At slaughter, hot carcass weight and yield and carcass classification were determined in 2 representative heifers per pen (12 animals per dietary treatment). Supplementation with malate salts or did not affect concentrate ADFI ( = 0.98), ADG ( = 0.74), or G:F ( = 0.50) at any time during the experiment. At slaughter, there were no differences in carcass weight ( = 0.86), classification ( = 0.18), or carcass yield ( = 0.84) among experimental groups. Also, there were no differences treatments on ruminal pH ( = 0.24), ruminal fermentation products ( = 0.69, = 0.88, and = 0.93 for total VFA, NH-N, and lactate, respectively), and blood metabolites ( = 0.96, = 0.82, and = 0.15 for glucose, urea N, and lactate, respectively). In conclusion, under the feeding and management conditions of this study, diet supplementation with malate salts or did not have any significant effects on growth performance, carcass quality, ruminal fermentation products, and blood metabolites.

Application of anhydrobiosis and dehydration of yeasts for non-conventional biotechnological goals

Dehydration of yeast cells causes them to enter a state of anhydrobiosis in which their metabolism is temporarily and reversibly suspended. This unique state among organisms is currently used in the production of active dry yeasts, mainly used in baking and winemaking. In recent decades non-conventional applications of yeast dehydration have been proposed for various modern biotechnologies. This mini-review briefly summarises current information on the application of dry yeasts in traditional and innovative fields. It has been shown that dry yeast preparations can be used for the efficient protection, purification and bioremediation of the environment from heavy metals. The high sorption activity of dehydrated yeasts can be used as an interesting tool in winemaking due to their effects on quality and taste. Dry yeasts are also used in agricultural animal feed. Another interesting application of yeast dehydration is as an additional stage in new methods for the stable immobilisation of microorganisms, especially in cases when biotechnologically important strains have no affinity with the carrier. Such immobilisation methods also provide a new approach for the successful conservation of yeast strains that are very sensitive to dehydration. In addition, the application of dehydration procedures opens up new possibilities for the use of yeast as a model system. Separate sections of this review also discuss possible uses of dry yeasts in biocontrol, bioprotection and biotransformations, in analytical methods as well as in some other areas.

Influence of Feeding Enzymatically Hydrolyzed Yeast Cell Wall on Growth Performance and Digestive Function of Feedlot Cattle during Periods of Elevated Ambient Temperature

In experiment 1, eighty crossbred steers (239±15 kg) were used in a 229-d experiment to evaluate the effects of increasing levels of enzymatically hydrolyzed yeast (EHY) cell wall in diets on growth performance feedlot cattle during periods of elevated ambient temperature. Treatments consisted of steam-flaked corn-based diets supplemented to provide 0, 1, 2, or 3 g EHY/hd/d. There were no effects on growth performance during the initial 139-d period. However, from d 139 to harvest, when 24-h temperature humidity index averaged 80, EHY increased dry matter intake (DMI) (linear effect, p<0.01) and average daily gain (ADG) (linear effect, p = 0.01). There were no treatment effects (p>0.10) on carcass characteristics. In experiment 2, four Holstein steers (292±5 kg) with cannulas in the rumen and proximal duodenum were used in a 4×4 Latin Square design experiment to evaluate treatments effects on characteristics of ruminal and total tract digestion in steers. There were no treatment effects (p>0.10) on ruminal pH, total volatile fatty acid, molar proportions of acetate, butyrate, or estimated methane production. Supplemental EHY decreased ruminal molar proportion of acetate (p = 0.08), increased molar proportion of propionate (p = 0.09), and decreased acetate:propionate molar ratio (p = 0.07) and estimated ruminal methane production (p = 0.09). It is concluded that supplemental EHY may enhance DMI and ADG of feedlot steers during periods of high ambient temperature. Supplemental EHY may also enhance ruminal fiber digestion and decrease ruminal acetate:propionate molar ratios in feedlot steers fed steam-flaked corn-based finishing diets.