Live yeasts enhance fibre degradation in the cow rumen through an increase in plant substrate colonization by fibrolytic bacteria and fungi

Effects of rehydrated corn silage inoculated with Rhodotorula mucilaginosa + Trichoderma longibrachiatum on finisher lambs fed a tropical hay-based diet

It is well established in the scientific literature that tropical forages are characterized by low soluble carbohydrates and a high proportion of cell walls containing lignin, negatively impacting animal productivity. Using live microorganisms in diets, such as fungi and yeasts, can benefit animal nutrition and health. This study assessed the effects of using rehydrated ground corn silage as a vehicle for providing an inoculant composed of fungus and yeast (Rhodotorula mucilaginosa + Trichoderma longibrachiatum) isolated from the gastrointestinal contents of sheep on the productive performance of confined lambs. Twenty-two entire male lambs of the Dorper × Santa Inês breed (14.20 ± 1.74 kg body weight) were randomly assigned to two treatments: 1) control diet containing rehydrated corn silage without inoculant (CTL); 2) diet containing rehydrated ground corn silage with inoculant of indigenous microorganisms (INO). Rhodotorula mucilaginosa and Trichoderma longibrachiatum were observed only in samples of rehydrated corn with inoculant (P<0.0001). The inoculated silage had lower neutral detergent fiber (NDF) content (89.9g/kg dry matter - DM) than the control silage (134.8g/kg DM). CTL treatment showed higher other mycelial fungi count than treatment INO (P=0.04). However, the total count of mycelial fungi did not differ between treatments. Treatments did not affect silage pH; however, pH was reduced in samples taken 56 days after ensiling (P<0.001). No differences were observed between treatments for DM digestibility and nutrient and nitrogen balance (P<0.05). Although the combination of microorganisms reduced dry matter intake (DMI) (P<0.05), no treatment effect was observed on growth performance over the 63-day experimental period. These results indicate that Rhodotorula mucilaginosa and Trichoderma longibrachiatum inoculated in rehydrated corn silage can improve feed quality by lowering fiber content without compromising animal growth. In conclusion, feeding lamb with rehydrated corn silage inoculated with Rhodotorula mucilaginosa and Trichoderma longibrachiatum reduces dry matter intake of tropical hay-based diets without affecting body weight gain.

Quantification of the Environmental Impact of Feeding Yeast Probiotic Saccharomyces cerevisiae Actisaf Sc 47 in Dairy Cow: A Life Cycle Assessment Approach

Today, one of the major challenges of dairy farmers is to reduce their environmental footprint to establish more effective, efficient, and sustainable production systems. Feed additives such as yeast probiotics could potentially allow them to achieve these objectives through the improvement of milk production, feed efficiency, and ration valorization, hence mitigating the environmental impacts of milk production. In this study, the life cycle assessment (LCA) principle was performed to estimate the environmental impact of the production and supplementation of a commercial yeast probiotic (Actisaf Sc 47) in three trials performed in three different countries that are representative for around 50% of the milk production in Europe: France (French trial), United Kingdom (UK trial), and Germany (German trial). For each trial, two groups of animals were compared: control, without Actisaf Sc 47 supplementation, used as baseline; and experimental, with Actisaf Sc 47 supplementation at 5 or 10 g/cow/day. Different impact categories were analyzed for each group to calculate the impact of producing 1 kg of fat- and protein-corrected milk. An initial analysis was done only during the period of Actisaf Sc 47 supplementation and showed than the supplementation with Actisaf Sc 47 reduced, on average by 5%, the carbon footprint during the three trials. A second analysis was done via the extrapolation of all the data of each trial to an annual farm level, including the lactation period (305 days), dry period (60 days), and the period with and without Actisaf Sc 47 supplementation. Reported at a farm annual scale, the average reduction allowed by Actisaf Sc 47 supplementation was 2.9, 2.05, 2.47, 1.67, 2.28, 2.18, 2.14, and 2.28% of the carbon footprint, land use, water use, resource use, acidification, freshwater eutrophication, marine eutrophication, and terrestrial eutrophication, respectively. On average, the production of 1 kg of fat- and protein-corrected milk by using Actisaf Sc 47 was shown to improve environmental impacts compared to control. Regarding Actisaf Sc 47 production, the LCA showed that the production of 1 kg of Actisaf Sc 47 emitted 2.1 kg CO2 eq with a negligible contribution to total the carbon footprint of milk ranging from 0.005 to 0.016%. The use of Actisaf Sc 47 in dairy cows could then result in different positive outcomes: improving performance and efficiency while reducing the global carbon footprint.

Alfalfa supplementation timing changes the rumen archaeal and fungal community composition and colonization in pre-weaning lambs

The establishment of the rumen microbiota plays an important role in the rumen development. However, little is known about the effects of alfalfa supplementation time on rumen microbiota establishment. Here, a total of 42 Hu lambs, seven-day-old, were chosen for the study. After a week of adjustment, six lambs were sacrificed to establish a baseline. The remaining 36 lambs were randomly split into two groups: one receiving alfalfa hay at 14 days (EAF), the other at 42 days (LAF), both groups received milk replacer and starter pellets. Introducing alfalfa at 14 days of age significantly improved total dry matter intake between 28 and 42 days (p = 0.04) and average daily gain from both 14 to 28 days (p = 0.04) and 28 to 42 days (p < 0.01), but this effect disappears from 56 to 70 days (p > 0.05). At 42 days, the abundances of Naganishia, Ascochyta, and Neosetophoma in the EAF group were significantly higher (p < 0.05) than those in the LAF group (17.8% vs. 3.97, 10.89% vs. 1.77, and 1.27% vs. 0.09%, respectively). At 56 days, the abundances of Ascochyta, Wallemia, and Aspergillus in the EAF group were significantly lower (p < 0.05) than in the LAF group (3.53% vs. 16.40, 8.78% vs. 18.89, and 2.14% vs. 4.69%). At 70 days, Aspergillus abundance in the EAF group was significantly higher (p < 0.05) than in the LAF group (2.69% vs. 0.85%). The LEfSe analysis showed that Methanobrevibacter_smithii was the archaeal biomarker at 14 days in both groups. Methanobrevibacter_sp_AbM4 was enriched at 56 days in the LAF group. Compared to the LAF group, the specific fungal biomarkers in the EAF group included Sporobolomyces and Bullera at 14 days, Naganishia, Didymella, Cleistothelebolus, and Alloleptosphaeria at 42 days, Ascochyta, Neoascochyta, and Alfaria at 70 days. Correlation analysis results showed strong patterns of association both within and between archaea and fungi, which were influenced by alfalfa supplementation time. In summary, alfalfa supplementation at 14 days of age promotes the growth performance of lambs before weaning, and alfalfa supplementation timing significantly affects rumen archaeal and fungal communities and dynamical changes.

Understanding the Diversity and Roles of the Ruminal Microbiome

The importance of ruminal microbiota in ruminants is emphasized, not only as a special symbiotic relationship with ruminants but also as an interactive and dynamic ecosystem established by the metabolites of various rumen microorganisms. Rumen microbial community is essential for life maintenance and production as they help decompose and utilize fiber that is difficult to digest, supplying about 70% of the energy needed by the host and 60-85% of the amino acids that reach the small intestine. Bacteria are the most abundant in the rumen, but protozoa, which are relatively large, account for 40-50% of the total microorganisms. However, the composition of these ruminal microbiota is not conserved or constant throughout life and is greatly influenced by the host. It is known that the initial colonization of calves immediately after birth is mainly influenced by the mother, and later changes depending on various factors such as diet, age, gender and breed. The initial rumen microbial community contains aerobic and facultative anaerobic bacteria due to the presence of oxygen, but as age increases, a hypoxic environment is created inside the rumen, and anaerobic bacteria become dominant in the rumen microbial community. As calves grow, taxonomic diversity increases, especially as they begin to consume solid food. Understanding the factors affecting the rumen microbial community and their effects and changes can lead to the early development and stabilization of the microbial community through the control of rumen microorganisms, and is expected to ultimately help improve host productivity and efficiency.

Sodium butyrate administration improves intestinal development of suckling lambs

This study was conducted to investigate the effects of sodium butyrate (SB) supplementation on growth performance, intestinal barrier functions, and intestinal bacterial communities in sucking lambs. Forty lambs of 7 d old, with an average body weight (BW) of 4.46 ± 0.45 kg, were allocated into the control (CON) or SB group, with each group having five replicate pens (n = 5). Lambs were orally administered SB at 1.8 mL/kg BW in the SB group or the same volume of saline in the CON group. Treatments were administered from 7 to 35 d of age, when one lamb from each replicate was slaughtered to obtain intestinal tissues and contents. The results showed that supplementation with SB tended to increase the BW (P = 0.079) and the starter intake (P = 0.089) of lambs at 35 d of age. The average daily gain of lambs in the SB group was significantly greater than that in the CON group (P < 0.05). The villus height of jejunum in the SB group was markedly higher (P < 0.05) than that in the CON group. In ileum, lambs in the SB group had lower (P < 0.05) crypt depth and greater (P < 0.05) villus-to-crypt ratio than those in the CON group. Compared with the CON group, the mRNA and protein expressions of Claudin-1 and Occludin were increased (P < 0.05) in the SB group. Supplementation with SB decreased the relative abundances of pathogenic bacteria, including Clostridia_UCG-014 (P = 0.094) and Romboutsia (P < 0.05), which were negatively associated with the intestinal barrier function genes (P < 0.05). The relative abundance of Succiniclasticum (P < 0.05) was higher in the SB group, and it was positively correlated with the ratio of villi height to crypt depth in the jejunum (P < 0.05). Compared with the CON group, the function "Metabolism of Cofactors and Vitamins" was increased in the SB group lambs (P < 0.05). In conclusion, SB orally administration during suckling period could improve the small intestine development and growth performance of lambs by inhibiting the harmful bacteria (Clostridia_UCG-014, Romboutsia) colonization, and enhancing intestinal barrier functions.

Effects of live and autolyzed yeast supplementation during transition period on ruminal fermentation, blood attributes, and immune response in dairy cows under heat stress condition

This study was conducted to compare nutrient digestibility, performance and immune response of dairy cows received live and autolyzed yeast during the transition period in high ambient temperature. Cows (n = 25) were randomly divided and received a basal diet with or without live yeast or autolyzed yeast as on top three weeks pre-parturition until three weeks post-parturition. The Control group received a basal diet without yeast products; other groups received 0.5 g live yeast; 1.0 g live yeast; 10 g autolyzed yeast and 20 g/d/head autolyzed yeast. Live yeast resulted in higher nutrient digestibility compared with autolyzed yeast and the control. Methane production was the highest in autolyzed yeast and the lowest in live yeast. Average milk production was the highest in cows that received live yeast. The highest IgG level was for cows that received autolyzed yeast at a dose of 20 g/d/head. Live yeast had no significant effect, but autolyzed yeast increased the relative expression of γ-Interferon and interleukin-2 as compared with the control group. It was concluded that live yeast at a dose of 1.0 g/d/head could influence ruminal fermentation and milk production, but autolyzed yeast at a dose of 20 g/d/head could influence the immune response of dairy cows during the transition period and heat stress.

Dietary Live Yeast Supplementation Influence on Cow’s Milk, Teat and Bedding Microbiota in a Grass-Diet Dairy System

The supplementation of animal feed with microbial additives remains questioning for the traditional or quality label raw milk cheeses with regard to microbial transfer to milk. We evaluated the effect of dietary administration of live yeast on performance and microbiota of raw milk, teat skin, and bedding material of dairy cows. Two balanced groups of cows (21 primiparous 114 ± 24 DIM, 18 multiparous 115 ± 33 DIM) received either a concentrate supplemented with Saccharomyces cerevisiae CNCM I-1077 (1 × 1010 CFU/d) during four months (LY group) or no live yeast (C group). The microbiota in individual milk samples, teat skins, and bedding material were analysed using culture dependent techniques and high-throughput amplicon sequencing. The live yeast supplementation showed a numerical increase on body weight over the experiment and there was a tendency for higher milk yield for LY group. A sequence with 100% identity to that of the live yeast was sporadically found in fungal amplicon datasets of teat skin and bedding material but never detected in milk samples. The bedding material and teat skin from LY group presented a higher abundance of Pichia kudriavzevii reaching 53% (p < 0.05) and 10% (p < 0.05) respectively. A significant proportion of bacterial and fungal ASVs shared between the teat skin and the milk of the corresponding individual was highlighted.

The Role of Yeast Saccharomyces cerevisiae in Supporting Gut Health in Horses: An Updated Review on Its Effects on Digestibility and Intestinal and Fecal Microbiota

To support the overall health of horses, it is essential to maintain an optimal gut health (GH) status, which encompasses several physiological and functional aspects, including the balance and functionality of intestinal microbial populations and, accordingly, the effective digestion and absorption of nutrients. Numerous biotic and abiotic stressors can lead to an imbalance of GH, such as the quality of forages and the composition of diet, e.g., the inclusion of high energy-dense feeds to meet the energy requirements of performance horses. To support the digestive function and the intestinal microbial populations, the diet can be supplemented with feed additives, such as probiotic yeasts, that promote the ability of cellulolytic bacteria in the hindgut to digest the available fiber fractions, finally increasing feed efficiency. Among the different yeasts available, S. cerevisiae is the most used in horses' nutrition; however, results of digestibility trials, as well as data on intestinal and fecal microbial populations, are sometimes contradictory. Therefore, the purpose of this review is to summarize the effects of S. cerevisiae on in vivo and in vitro digestibility, providing an updated overview of its effects on the intestinal and fecal microbial population.

Isolation and Characterization of Ruminal Yeast Strain with Probiotic Potential and Its Effects on Growth Performance, Nutrients Digestibility, Rumen Fermentation and Microbiota of Hu Sheep

Yeast strains are widely used in ruminant production. However, knowledge about the effects of rumen native yeasts on ruminants is limited. Therefore, this study aimed to obtain a rumen native yeast isolate and investigate its effects on growth performance, nutrient digestibility, rumen fermentation and microbiota in Hu sheep. Yeasts were isolated by picking up colonies from agar plates, and identified by sequencing the ITS sequences. One isolate belonging to Pichia kudriavzevii had the highest optical density among these isolates obtained. This isolate was prepared to perform an animal feeding trial. A randomized block design was used for the animal trial. Sixteen Hu sheep were randomly assigned to the control (CON, fed basal diet, n = 8) and treatment group (LPK, fed basal diet plus P. kudriavzevii, CFU = 8 × 10⁹ head/d, n = 8). Sheep were housed individually and treated for 4 weeks. Compared to CON, LPK increased final body weight, nutrient digestibility and rumen acetate concentration and acetate-to-propionate ratio in sheep. The results of Illumina MiSeq PE 300 sequencing showed that LPK increased the relative abundance of lipolytic bacteria (Anaerovibrio spp. and Pseudomonas spp.) and probiotic bacteria (Faecalibacterium spp. and Bifidobacterium spp.). For rumen eukaryotes, LPK increased the genera associated with fiber degradation, including protozoan Polyplastron and fungus Pichia. Our results discovered that rumen native yeast isolate P. kudriavzevii might promote the digestion of fibers and lipids by modulating specific microbial populations with enhancing acetate-type fermentation.

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 feeding a live yeast on rumen fermentation and fiber degradability of tropical and subtropical forages

BACKGROUND

The effect of live yeast Saccharomyces cerevisiae strain CNCM I-1077 (SC) on the ruminal degradability of different forages commonly found in dairy diets in South America was evaluated. We also assessed if SC supplementation interacts with forage group to affect ruminal fiber degradability. Four non-lactating rumen-cannulated Holstein cows were randomly assigned to two treatment sequences: Control-SC-Control or SC-Control-SC, in a switchback design, with three 30-day periods. Cows in the SC treatment were supplied with 1 × 10¹⁰ colony-forming units of yeast daily via rumen cannula. In situ degradability of dry matter (DM) and neutral detergent fiber (aNDF) was measured in 15 forages collected in South America. Forages were assigned to one of three groups: corn silages; tropical grasses (sugarcane silages and tropical grass silages); and temperate grasses and alfalfa (oat silages, ryegrass silages, alfalfa silage, and alfalfa hay).

RESULTS

Cows supplemented with SC had higher (P = 0.05) counts of yeasts and lower (P = 0.03) concentration of lactate in rumen fluid. There was no interaction between forage group and yeast supplementation (P > 0.10) on in situ degradability. The SC increased DM (by 4.6%) and aNDF degradation (by 10.3%) at 24 h of incubation (P < 0.05). Metabolomics revealed that a chemical entity (C₁₇ H₂₉ N₆ O₃ , m/z 365.2284 [M + H]⁺ ) from the family of lipids and related molecules was suppressed in the rumen fluid of cows supplemented with SC.

CONCLUSION

The SC supplementation improved DM and aNDF degradability regardless of the forage group. © 2021 Society of Chemical Industry.

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.

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

Urea–lime-treated rice straw fed to Thai native beef cattle was supplemented with dry yeast (DY) (Saccharomyces cerevisiae) to assess total feed intake, nutrient digestibility, rumen microorganisms, and methane (CH4) production. Sixteen Thai native beef cattle at 115 ± 10 kg live weight were divided into four groups that received DY supplementation at 0, 1, 2, and 3 g/hd/d using a randomized completely block design. All animals were fed concentrate mixture at 0.5% of body weight, with urea–lime-treated rice straw fed ad libitum. Supplementation with DY enhanced total feed intake and digestibility of neutral detergent fiber and acid detergent fiber (p < 0.05), but dry matter, organic matter and crude protein were similar among treatments (p > 0.05). Total volatile fatty acid (VFA) and propionic acid (C3) increased (p < 0.05) with 3 g/hd/d DY supplementation, while acetic acid (C2) and butyric acid (C4) decreased. Protozoal population and CH4 production in the rumen decreased as DY increased (p < 0.05). Populations of F. succinogenes and R. flavefaciens increased (p < 0.05), whereas methanogen population decreased with DY addition at 3 g/hd/d, while R. albus was stable (p > 0.05) throughout the treatments. Thus, addition of DY to cattle feed increased feed intake, rumen fermentation, and cellulolytic bacterial populations.

Changes in Digestive Microbiota, Rumen Fermentations and Oxidative Stress around Parturition Are Alleviated by Live Yeast Feed Supplementation to Gestating Ewes

Background: In ruminants, physiological and nutritional changes occur peripartum. We investigated if gastro-intestinal microbiota, rumen metabolism and antioxidant status were affected around parturition and what could be the impact of a daily supplementation of a live yeast additive in late gestating ewes. Methods: Rumen, feces and blood samples were collected from 2 groups of 14 ewes one month and a few days before parturition, and 2 weeks postpartum. Results: In the control ewes close to parturition, slight changes in the ruminal microbiota were observed, with a decrease in the concentration F. succinogenes and in the relative abundance of the Fibrobacteres phylum. Moreover, a decrease in the alpha-diversity of the bacterial community and a reduced relative abundance of the Fibrobacteres phylum were observed in their feces. Control ewes were prone to oxidative stress, as shown by an increase in malondialdehyde (MDA) concentration, a lower total antioxidant status, and higher glutathione peroxidase (GPx) activity in the blood. In the yeast supplemented ewes, most of the microbial changes observed in the control group were alleviated. An increase in GPx activity, and a significant decrease in MDA concentration were measured. Conclusions: The live yeast used in this study could stabilize gastro-intestinal microbiota and reduce oxidative stress close to parturition.

Association of ionophores, yeast, and bacterial probiotics alters the abundance of ruminal microbial species of pasture intensively finished beef cattle

The effect of the association of non-protein nitrogen, yeast, and bacterial probiotics on the ruminal microbiome of beef cattle intensively finished on pasture was evaluated. The experiment was carried out in a completely randomized design with five treatments and four replications. The treatments consisted of a group of animals kept on pasture that received low consumption supplementation (LS) and four groups that received for 98 days, 17.5 g concentrate kg^-1 body weight. The supplements were composed of the association of additives: urea (U), slow-release non-protein nitrogen (U+SRN), yeast (Saccharomyces cerevisiae; U+SRN+Y), and bacterial probiotics (live strains of bacteria; U+SRN+Y+BP). All supplements also contained salinomycin and virginiamycin. After slaughtering the animals, samples of ruminal content were collected to quantify groups of fibrolytic bacteria (Ruminococcus albus and Fibrobacter succinogenes), non-fibrolytic (Prevotella ruminicola, Selenomonas ruminantium, and Streptococcus bovis), Archaea, and ciliate protozoa, using the qPCR technique. The abundance of F. succinogenes was the same for the LS animals and those that received the supplement U+SRN+Y (1.42×10⁸ copies mL^-1) but higher than the other treatments. Supplementation reduced by 90% the abundance of S. bovis compared to the LS. The inclusion of yeast increased the abundance of fibrolytic bacteria by 2.2-fold. For animals that received the supplement U+SRN+Y+BP and the LS, there was no difference for non-fibrolytic bacteria (3.07×10⁹ copies mL^-1). The use of yeasts and sources of non-protein nitrogen in high-concentrate diets for beef cattle stimulates the growth of fibrolytic bacteria, which can contribute to the reduction of digestive disorders and metabolic diseases in animals that receive diets with high concentrate in pasture intensive termination systems.

The use of live yeast to increase intake and performance of cattle receiving low-quality tropical forages

The objective was to evaluate the effects of a specific strain of live yeast (LY) on growth performance, fermentation parameters, feed efficiency, and bacterial communities in the rumen of growing cattle fed low-quality hay. In experiment (exp.) 1, 12 Droughtmaster bull calves (270 ± 7.6 kg initial body weight [BW]) were blocked by BW into two groups, allocated individually in pens, and fed ad libitum Rhodes grass hay (8.4% of crude protein [CP]) and 300 g/bull of supplement (52% CP) without (Control) or with LY (8 × 109 colony-forming unit [CFU]/d Saccharomyces cerevisiae CNCM I-1077; Lallemand Inc., Montreal, Canada) for 28 d, followed by 7 d in metabolism crates. Blood and rumen fluid were collected before feeding and 4 h after feeding. In exp. 2, for assessment of growth performance, 48 Charbray steers (329 ± 20.2 kg initial BW) were separated into two blocks by initial BW and randomly allocated into 12 pens. The steers were fed Rhodes grass hay (7.3% CP) and 220 g/steer of supplement (60% CP) without or with LY (8 × 109 CFU/d) for 42 d, after a 2-wk adaptation period. In exp. 1, fiber digestibility was calculated from total fecal collection, and, in exp 2, indigestible neutral detergent fiber (NDF) was used as a marker. Inclusion of LY increased (P = 0.03) NDF intake by 8.3% in exp. 1, without affecting total tract digestibility. No changes were observed in microbial yield or in the efficiency of microbial production. There was a Treatment × Time interaction (P < 0.01) for the molar proportion of short-chain fatty acids, with LY increasing propionate before feeding. Inclusion of LY decreased rumen ammonia 4 h after feeding (P = 0.03). The addition of LY reduced rumen bacterial diversity and the intraday variation in bacterial populations. Relative populations of Firmicutes and Verrucomicrobia varied over time (P < 0.05) only within the Control group. At the genus level, the relative abundance of an unclassified bacterial genus within the order Clostridiales, a group of cellulolytic bacteria, was reduced from 0 to 4 h after feeding in the Control group (P = 0.02) but not in the LY group (P = 1.00). During exp. 2, LY tended to increase average daily gain (ADG) (P = 0.08) and feed efficiency (P = 0.10), with no effect on NDF intake or digestibility. In conclusion, S. cerevisiae CNCM I-1077 reduced the intraday variation of rumen bacteria and increased the amount of NDF digested per day. These observations could be associated with the tendency of increased ADG and feed efficiency in growing cattle fed a low-quality forage.

Effects of Saccharomyces cerevisiae, medium and forage type and their interactions on in vitro ruminal fermentation

The objective of this study was to investigate the effects of a live yeast, Saccharomyces cerevisiae CNCM I-1077, at four doses (0, 1×10⁵, 1×10⁶ and 1 × 10⁷ cfu/mL) according to the reducing medium used [Goering-Van Soest (GV), McDougall (MD) or Kansas State (KS)] on in vitro ruminal neutral detergent fibre digestibility (NDFd), rate of digestion of NDF (kd), organic matter digestibility (OMd), dry matter digestibility (DMd), pH as well as volatile fatty acids (VFA) concentration, using two forages (oat hay and wheat straw) with differing chemical composition. The maximum in vitro NDFd, DMd, OMd as well as kd were obtained with dose 1 × 10⁶ cfu/mL, although differences between doses were not always significant. The pH estimates were the lowest with the 1 × 10⁷ cfu/mL dose, but the differences were not all significant; however, 1 × 10⁷ cfu/mL corresponded to significantly lower pH estimates compared to the control and 1×10⁵ (6.51 vs. 6.60 and 6.59, respectively). The decrease in pH was accompanied by an increase in VFA concentrations as the yeast dose increased. The KS medium resulted in the lowest digestibility estimates, pH estimates as well as kd, regardless of yeast dose. The 1 × 10⁶ cfu/mL was the better performing yeast dose in vitro resulting in higher digestibility estimates which indicates the yeasts ability to stimulate the microorganisms within the rumen by beneficially modifying rumen environment, thus promoting microbiota activity. The MD and GV media provide better environments for fermentation than the KS medium, resulting in higher in vitro NDFd, DMd, OMd, pH estimates as well as rate of NDF digestion. The MD and GV are also the media that resulted in more consistent results when analysing the effects of the live yeast. Our data suggest that the in vitro conditions have to be carefully chosen to be able to demonstrate rumen fermentation shifts with the use of live microbial additives.

Live yeast supplementation during late gestation and lactation affects reproductive performance, colostrum and milk composition, blood biochemical and immunological parameters of sows

This study was conducted to evaluate the effects of dietary live yeast (LY) supplementation during late gestation and lactation on reproductive performance, colostrum and milk composition, blood biochemical and immunological parameters of sows. A total of 40 multiparous sows were randomly fed either the control (CON) diet or the CON diet supplemented with LY at 1 g/kg from d 90 of gestation to weaning. Results showed that the number of stillborn piglets and low BW piglets were significantly decreased in the LY-supplemented sows compared with sows in the CON group (P < 0.05). Moreover, the concentrations of protein, lactose and solids-not-fat were increased in the colostrum of LY-supplemented sows (P < 0.05). Interestingly, the plasma activities of aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (γ-GGT) at d 1 of lactation and alanine aminotransferase (ALT) at weaning day were decreased by feeding LY diet (P < 0.05). Meanwhile, sows fed LY diet had higher plasma concentration of immunoglobulin G compared with sows fed CON diet at d 1 of lactation (P < 0.05). In conclusion, LY supplementation in maternal diets decreased the number of stillborn piglets and low BW piglets, improved colostrum quality and health status of sows.

Supplementation of live yeast based feed additive in early life promotes rumen microbial colonization and fibrolytic potential in lambs

Rumen microbiota is of paramount importance for ruminant digestion efficiency as the microbial fermentations supply the host animal with essential sources of energy and nitrogen. Early separation of newborns from the dam and distribution of artificial milk (Artificial Milking System or AMS) could impair rumen microbial colonization, which would not only affect rumen function but also have possible negative effects on hindgut homeostasis, and impact animal health and performance. In this study, we monitored microbial communities in the rumen and the feces of 16 lambs separated from their dams from 12 h of age and artificially fed with milk replacer and starter feed from d8, in absence or presence of a combination of the live yeast Saccharomyces cerevisiae CNCM I-1077 and selected yeast metabolites. Microbial groups and targeted bacterial species were quantified by qPCR and microbial diversity and composition were assessed by 16S rDNA amplicon sequencing in samples collected from birth to 2 months of age. The fibrolytic potential of the rumen microbiota was analyzed with a DNA microarray targeting genes coding for 8 glycoside hydrolase (GH) families. In Control lambs, poor establishment of fibrolytic communities was observed. Microbial composition shifted as the lambs aged. The live yeast supplement induced significant changes in relative abundances of a few bacterial OTUs across time in the rumen samples, among which some involved in crucial rumen function, and favored establishment of Trichostomatia and Neocallimastigaceae eukaryotic families. The supplemented lambs also harbored greater abundances in Fibrobacter succinogenes after weaning. Microarray data indicated that key cellulase and hemicellulase encoding-genes were present from early age in the rumen and that in the Supplemented lambs, a greater proportion of hemicellulase genes was present. Moreover, a higher proportion of GH genes from ciliate protozoa and fungi was found in the rumen of those animals. This yeast combination improved microbial colonization in the maturing rumen, with a potentially more specialized ecosystem towards efficient fiber degradation, which suggests a possible positive impact on lamb gut development and digestive efficiency.

Maturation of the Goat Rumen Microbiota Involves Three Stages of Microbial Colonization

Simple Summary

Considerable attention has recently been focused on the rumen microbiome, which has been implicated in regulating a ruminant’s nutrient metabolism. From birth onwards, the colonization of the rumen microbial community is thus of crucial importance for growth and fiber digestion of goats. In this study, we have provided details of the progression of changes and colonization of ruminal bacteria and fungi before weaning. We have also predicted the molecular functions of the bacterial microbiota using CowPi. Our finding confirmed that maturation of the goat rumen microbiota involves three stages of core microbial colonization. The study of rumen microbial of young ruminants will benefit the optimization of feeding strategies to promote the development and digestion of a healthy rumen microbiota in later life.

Abstract

With increasing age, the rumen microbiota of new-born ruminants become central in the translation of fibrous feed substances into essential nutrients. However, the colonization process of the microbial community (especially fungal community) remains poorly understood in ruminants at pre-weaning stages. In this study, the rumen bacterial and fungal colonization processes were investigated in goats at eight stages using amplicon sequencing. For bacteria, we found 36 common core genera at D0, D3, D14, D28, and D56, including mainly Bacillus, Alloprevotella, Bacteroides, Prevotella_1, Lactococcus, and Ruminococcaceae_NK4A214. Firmicutes was the dominant phylum among the total microbiota in newborn goat kids (prior to nursing), while Bacillus, Lactococcus, and Pseudomonas were predominant genera. Interestingly, the proportion of Bacillus was as high as 55% in newborn animals. After milk nursing, the predominant phylum changed to Bacteroidetes, while the proportion of Bacillus and Lactobacillus was very low. CowPi was used to predict the functional gene pathways and we found increases in the abundance of genes associated with amino acid related enzymes, DNA repair and recombination proteins, aminoacyl tRNA biosynthesis, and peptidases after D3. With regard to fungi, we found that there were 51 common genera at day 0 (D0), D3, D14, D28, and D56, including mainly Cryptococcus, Aspergillus, and Caecomyces. Aspergillus occupied approximately 47% at day 0, but then it decreased from day 3 to day 14. This study indicates that the core microbes of rumen emerged shortly after birth, but the abundance was very different from the core genus of the adult rumen. In addition, we also report a detailed scheme of the bacterial and fungal colonization process in rumens and propose three distinct stages during the rumen colonization process in pre-weaning goats, which will offer a reference for the development of milk substitutes for small ruminants.

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.

Effect of live yeast supplementation to gestating sows and nursery piglets on postweaning growth performance and nutrient digestibility

The objectives of the present study were to determine the effects of live yeast (LY) supplementation of sows during gestation and lactation and to determine the effects of supplementation of their offspring after weaning on growth performance and nutrient digestibility. A total of 40 sows were assigned to 2 dietary treatments (control vs. LY) based on parity and expected farrowing date. Birth weight, weaning weight, litter size, and mortality were measured. After weaning, 128 mixed-sex piglets (64 from each sow treatment) were selected based on their source litter and initial BW, and randomly assigned to 2 treatments (control or LY) at 4 pigs per pen (total of 32 pigs per treatment) for a 6-wk growth performance study. At the end of the growth performance trial, 2 barrows from each pen were moved to metabolism crates for total fecal collection for a digestibility trial. Addition of LY to the sow diets had no effects on birth weight, weaning weight, litter size at birth, and mortality. Piglets had greater BW on days 21 and 42 post-weaning when sows were fed diets supplemented with LY, and overall ADG was greater in piglets from sows that received LY (P < 0.05). There was no effect of sow and nursery diets on overall ADFI and G:F intake. Supplementing diets with LY during the nursery phase increased apparent total tract digestibility (ATTD) of DM, GE, and phosphorus (P) during this phase. The ATTD of GE was also greater in piglets from sows that received LY. In conclusion, LY supplementation of diets during gestation and lactation and during the nursery phase could increase ADG and ATTD of DM, GE, and P in the offspring, and this may lead to a greater lifetime growth performance in the offspring.

Influence of the microbiota-gut-brain axis on behavior and welfare in farm animals: A review

There is increasing evidence of a pivotal role of the gut microbiota (GUT-M) in key physiological functions in vertebrates. Many studies discuss functional implications of the GUT-M not only on immunity, growth, metabolism, but also on brain development and behavior. However, while the influence of the microbiota-gut-brain axis (MGBA) on behavior is documented in rodents and humans, data on farm animals are scarce. This review will first report the well-known influence of the MGBA on behavior in rodent and human and then describe its influence on emotion, memory, social and feeding behaviors in farm animals. This corpus of experiments suggests that a better understanding of the effects of the MGBA on behavior could have large implications in various fields of animal production. Specifically, animal welfare and health could be improved by selection, nutrition and management processes that take into account the role of the GUT-M in behavior.

Review: Are there indigenous Saccharomyces in the digestive tract of livestock animal species? Implications for health, nutrition and productivity traits

All livestock animal species harbour complex microbial communities throughout their digestive tract that support vital biochemical processes, thus sustaining health and productivity. In part as a consequence of the strong and ancient alliance between the host and its associated microbes, the gut microbiota is also closely related to productivity traits such as feed efficiency. This phenomenon can help researchers and producers develop new and more effective microbiome-based interventions using probiotics, also known as direct-fed microbials (DFMs), in Animal Science. Here, we focus on one type of such beneficial microorganisms, the yeast Saccharomyces. Saccharomyces is one of the most widely used microorganisms as a DFM in livestock operations. Numerous studies have investigated the effects of dietary supplementation with different species, strains and doses of Saccharomyces (mostly Saccharomyces cerevisiae) on gut microbial ecology, health, nutrition and productivity traits of several livestock species. However, the possible existence of Saccharomyces which are indigenous to the animals' digestive tract has received little attention and has never been the subject of a review. We for the first time provide a comprehensive review, with the objective of shedding light into the possible existence of indigenous Saccharomyces of the digestive tract of livestock. Saccharomyces cerevisiae is a nomadic yeast able to survive in a broad range of environments including soil, grass and silages. Therefore, it is very likely that cattle and other animals have been in direct contact with this and other types of Saccharomyces throughout their entire existence. However, to date, the majority of animal scientists seem to agree that the presence of Saccharomyces in any section of the gut only reflects dietary contamination; in other words, these are foreign organisms that are only transiently present in the gut. Importantly, this belief (i.e. that Saccharomyces come solely from the diet) is often not well grounded and does not necessarily hold for all the many other groups of microbes in the gut. In addition to summarizing the current body of literature involving Saccharomyces in the digestive tract, we discuss whether the beneficial effects associated with the consumption of Saccharomyces may be related to its foreign origin, though this concept may not necessarily satisfy the theories that have been proposed to explain probiotic efficacy in vivo. This novel review may prove useful for biomedical scientists and others wishing to improve health and productivity using Saccharomyces and other beneficial microorganisms.

The effect of Saccharomyces cerevisiae live cells and Aspergillus oryzae fermentation extract on the lactational performance of dairy cows

Eighty multiparous lactating Holstein cows (635 ± 33 kg) were used to study the effect of feeding Saccharomyces cerevisiae and/or Aspergillus oryzae on lactational performance for 14 weeks. Cows were assigned in a completely randomized experimental design, with repeated measures into four treatments, and were fed a basal diet of concentrates and forage at a ratio of 592:408, respectively. The treatments were: (1) the basal diet with no additive (Control treatment); (2) the basal diet supplemented with 3.5 g of live S. cerevisiae/cow daily (SC treatment); (3) the basal diet supplemented with 3.5 g A. oryzae fermentation extract/cow daily (AO treatment); and (4) the basal diet supplemented with 3.5 g of live S. cerevisiae + 3.5 g A. oryzae fermentation extract/cow daily (AOSC treatment). The AO and AOSC treatments increased (p < .05) feed intake and daily milk production, with a low milk fat content for the AO treatment. Feeding SC treatment decreased (p = .002) serum glucose concentration, while the AOSC treatment increased serum glutamate-oxaloacetate transaminase concentration. It is concluded that S. cerevisiae supplementation did not enhance milk production; however, A. oryzae fermentation extract improved feed intake and milk production.

Effects of the Forage Type and Chop Length of Ramie Silage on the Composition of Ruminal Microbiota in Black Goats

The aim of this study was to investigate the effects of the forage type and chop length of ramie (Boehmeria nivea (L.) Gaud.) silage on rumen fermentation and ruminal microbiota in black goats. Sixteen Liuyang black goats (22.35 ± 2.16 kg) were fed with the roughage of corn silage or ramie silage at chop lengths of 1, 2, or 3 cm. The Chao 1 index and the observed number of microbial species differed significantly between the corn and ramie silage groups (p < 0.05); however, Firmicutes (relative proportion: 34.99-56.68%), Bacteroidetes (27.41-47.73%), and Proteobacteria (1.44-3.92%) were the predominant phyla in both groups. The relative abundance of Verrucomicrobia (0.32-0.82%) was lowest for the 2 and 3 cm chop lengths (p < 0.05) and was negatively correlated with rumen pH and propionic acid concentration (p < 0.05), but positively correlated with the ratio of acetic acid to propionic acid (p < 0.05). The ramie silage fermentation quality was highest for the 1 cm chop length, suggesting that moderate chopping produces optimal quality silage.

Inclusion of yeast waste as a protein source to replace soybean meal in concentrate mixture on ruminal fermentation and gas kinetics using in vitro gas production technique

This experiment was conducted to investigate the utilisation of yeast waste as protein source to replace soybean meal in concentrate mixture on kinetic of gas, rumen ammonia-nitrogen and digestibility of nutrients by using in vitro gas production technique. The experimental design was a completely randomised design and the dietary treatments were replacing soybean meal with yeast wastein concentrate at the ratio of 100:0, 75:25, 50:50, 25:75 and 0:100, respectively. Yeast waste was obtained from KSL Green Innovation Public Co. Limited, Thailand. The gas production was recorded at 0, 0.5, 1, 2, 4, 6, 8, 12, 16, 24, 48, 72 and 96 h of incubation. The yeast waste contained 26.4% crude protein. Gas production from soluble fractions (a), gas production from the insoluble fraction (b), potential extent of gas production (a+b) and the gas production rate constants for the insoluble fraction (c) were not altered when increasing concentration of yeast waste replacing soybean meal (P &gt; 0.05). Cumulative gas production (at 96 h of incubation) ranged from 69.3 to 72.8 mL and was similar among treatments. Ruminal NH3-N concentration was linearly increased (P &lt; 0.05) whereas ruminal pH did not alter when inclusion various levels of yeast waste replacing soybean meal, which ranged from 15.2 to 19.1 mg/dL and 6.90 to 6.94, respectively. In vitro dry matter digestibility and in vitro organic matter digestibility did not changed by increasing levels of yeast waste in the diets (P &gt; 0.05), except only in vitro dry matter digestibility at 12 h, which higher in soybean meal:yeast waste at 25:75 ratio (P &lt; 0.05). Furthermore, propionate (C3) molar was linearly higher when compared between inclusion yeast waste and the control group whereas acetate was decreased quadratically (P &lt; 0.05) and protozoal population tended to be decreased (P = 0.07) when increasing the level of replacing yeast waste. In conclusion, yeast waste could replace soybean meal in concentrate mixture with no negative effect on gas kinetics, rumen fermentation and in vitro digestibility, and therefore its use in animal feeding would contribute to a reduction in environmental pollution.

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.

Effect of high-fat diet and growth stage on the diversity and composition of intestinal microbiota in healthy bovine livestock

BACKGROUND

This study aimed to investigate the composition of bacteria in the bovine rectum and their functions during growth, in relation to different diets. Fecal samples were collected from 6-, 12-, 18- and 24-month cattle fed high-fat diet, and healthy female parents fed regular diet. Total DNA was amplified (V3-V4 of 16S rRNA) and submitted to barcode-DNA pyrosequencing. Intestinal microbiota profiles and functions were then analyzed.

RESULTS

A total of 114 512 operational taxonomic units were detected from the 1 802 243 sequences obtained. In 6-month-old and female parent groups, the top three abundant phyla were Bacteroidetes (37.6%, 32.2%), Firmicutes (34.4%, 48.2%) and Proteobacteria (9.1%, 6.3%); in the 12-, 18- and 24-month groups, they were Proteobacteria (45.5%, 47.1%, 38.8%), Firmicutes (27.4%, 22.2%, 20.1%) and Bacteroidetes (14.9%, 19.4%, 17.7%), respectively. Paludibacter and Desulfopila in abundance showed negative (P < 0.001) and positive (P < 0.05) correlation, respectively, to cattle weight gain through metagenomic functional prediction of methane, cysteine and methionine metabolism. Meanwhile, cofactor/vitamin and amino acid metabolic processes were significantly higher in bacteria from the regular diet group than high-fat diet groups, with markedly lower cellular processes and signaling, and reduced glycan biosynthesis and metabolism (P < 0.01).

CONCLUSIONS

The 6-month cattle and female parents shared similar intestinal bacteria; the community structure of fecal microbiota was significantly affected by high-fat diet in older cattle. © 2017 Society of Chemical Industry.

Metagenomic investigation of gastrointestinal microbiome in cattle

The gastrointestinal (GI) tract, including the rumen and the other intestinal segments of cattle, harbors a diverse, complex, and dynamic microbiome that drives feed digestion and fermentation in cattle, determining feed efficiency and output of pollutants. This microbiome also plays an important role in affecting host health. Research has been conducted for more than a century to understand the microbiome and its relationship to feed efficiency and host health. The traditional cultivation-based research elucidated some of the major metabolism, but studies using molecular biology techniques conducted from late 1980’s to the late early 2000’s greatly expanded our view of the diversity of the rumen and intestinal microbiome of cattle. Recently, metagenomics has been the primary technology to characterize the GI microbiome and its relationship with host nutrition and health. This review addresses the main methods/techniques in current use, the knowledge gained, and some of the challenges that remain. Most of the primers used in quantitative real-time polymerase chain reaction quantification and diversity analysis using metagenomics of ruminal bacteria, archaea, fungi, and protozoa were also compiled.

Degradabilidade de gramíneas, fermentação e protozoários no rúmen de bovinos em dietas com diferentes aditivos

RESUMO Quatro bovinos, com fistulas ruminais, foram alimentados em Quadrado Latino com os tratamentos compreendendo a adição diária no rúmen de: levedura (5g), monensina(200mg), Fator P (3g) e controle. Foram determinadas a Degradabilidade in situ de três capins tropicais (Tifton-85, Brachiaria e Mombaça e silagem de Mombaça), o pH ruminal, produção de ácidos graxos voláteis, N-amoniacal e população de protozoários. Não foi observada interação significativa entre tratamentos e capins e diferenças significativas entre os tratamentos, exceto na fração b da Brachiaria e silagem de Mombaça. O Mombaça apresentou alta solubilidade da MS e da FDN em relação aos demais capins e a Brachiaria maior solubilidade da PB. O processamento do Mombaça na forma de silagem promoveu redução fração solúvel e degradabilidades potencial (DE) e efetiva (DE) da MS e FDN e aumento da fração solúvel e DE da PB. A monensina promoveu menor produção de ácido acético, maior de propiônico e menor acético:propiônico em relação a controle. A levedura e Fator P apresentaram maior concentração total de AGCC que a monensina e controle. A monensina promoveu aumento de protozoários Diplodiniinae em relação à dieta controle, mas não houve diferença na contagem de Entodinium e de total de ciliados entre os tratamentos. Capins tropicais na forma de feno e de silagem apresentam diferentes degradabilidade ruminal não sendo influenciados por aditivos na dieta, com exceção da monensina no capim Brachiaria e silagem de Mombaça, mas estes afetam a fermentação e a população de protozoários no rúmen.

Bioavailability of aflatoxin B1 and ochratoxin A, but not fumonisin B1 or deoxynivalenol, is increased in starch-induced low ruminal pH in nonlactating dairy cows

High-production dairy and beef systems require diets rich in starch. This practice may induce ruminal acidosis and also increase exposure to mycotoxins because starches in starch-rich diets are the main vehicles of mycotoxin contamination. The aim of this study was to investigate the effects of low ruminal pH on the bioavailability of 4 major mycotoxins [i.e., aflatoxin B₁ (AFB1), ochratoxin A (OTA), deoxynivalenol (DON), and fumonisin B₁ (FB1)]. Eight nonlactating dairy cows fitted with rumen cannulas were used in a double crossover experiment. The trial was divided into 4 periods with 2 periods per crossover. Cows were divided into 2 groups receiving a low (15% dry matter basis) and high-starch diet (30.8%) with and without live yeast supplementation (1×10¹⁰ cfu per cow) in the first and second crossover, respectively. At the end of each period, cows received a single dose of mycotoxin-contaminated feed containing 0.05, 0.2, 0.24, and 0.56mg of AFB1, OTA, DON, and FB1 per kg of feed, respectively. The fecal and urinary excretion of mycotoxins and their metabolites was monitored for up to 48h postdosing. As expected, ruminal pH decreased in cows fed the high-starch diet. The high-starch diet increased the bioavailability of OTA and AFB1. Urinary excretion of OTA 24h after mycotoxin administration increased 3-fold in the high-starch diet, correlated with lower fecal excretion. Similarly, a decrease in fecal excretion of AFB1 was accompanied by an increase in urinary excretion of its major metabolite, aflatoxin M₁, 48h after mycotoxin administration. In contrast to AFB1 and OTA, the bioavailability of DON and FB1 remained unchanged. Yeast supplementation had no effect on the excretion balance of these 2 mycotoxins. In conclusion, these results show that high-starch diets increased the bioavailability of OTA and AFB1, most probably through the lowering effect on ruminal pH. This greater bioavailability potentially increases the toxic effects of these mycotoxins.