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

In vitro fermentation end-products and rumen microbiome as influenced by microencapsulated phytonutrient pellets (LEDRAGON) supplementation

The objective of this study was to investigate the effect of microencapsulated bioactive compounds from lemongrass mixed dragon fruit peel pellet (MiEn-LEDRAGON) supplementation on fermentation characteristics, nutrient degradability, methane production, and the microbial diversity using in vitro gas production technique. The study was carried out using a completely randomized design (CRD) with five levels of MiEn-LEDRAGON supplementation at 0, 1, 2, 3, and 4% of the total dry matter (DM) substrate. Supplementation of MiEn-LEDRAGON in the diet at levels of 3 or 4% DM resulted in increased (p < 0.05) cumulative gas production at 96 hours (h) of incubation time, reaching up to 84.842 ml/ 0.5 g DM. Furthermore, supplementation with 3% MiEn-LEDRAGON resulted in higher in vitro nutrient degradability and ammonia-nitrogen concentration at 24 h of the incubation time when compared to the control group (without supplementation) by 5.401% and 11.268%, respectively (p < 0.05). Additionally, supplementation with MiEn-LEDRAGON in the diet led to an increase in the population of Fibrobacter succinogenes at 24 h and Butyrivibrio fibrisolvens at 12 h, while decreasing the population of Ruminococcus albus, Ruminococcus flavefaciens, and Methanobacteriales (p < 0.05). Moreover, supplementation of MiEn-LEDRAGON in the diet at levels of 2 to 4% DM resulted in a higher total volatile fatty acids (VFA) at 24 h, reaching up to 73.021 mmol/L (p < 0.05). Additionally, there was an increased proportion of propionic acid (C3) and butyric acid (C4) at 12 h (p < 0.05). Simultaneously, there was a decrease in the proportion of acetic acid (C2) and the ratio of acetic acid to propionic acid (C2:C3), along with a reduction of methane (CH4) production by 11.694% when comparing to the 0% and 3% MiEn-LEDRAGON supplementation (p < 0.05). In conclusion, this study suggests that supplementing MiEn-LEDRAGON at 3% of total DM substrate could be used as a feed additive rich in phytonutrients for ruminants.

Effect of cassava pulp treated with Lactobacillus casei TH14, urea, and molasses on gas kinetics, rumen fermentation, and degradability using the in vitro gas technique

This study focused on examining the gas dynamics, rumen fermentation, and digestibility of ensiled cassava pulp (CSVP) using Lactobacillus casei TH14, urea, and molasses in the context of a laboratory experiment. All data in this study were analyzed using treatments arranged in 2 × 2 × 2 factorial arrangements using a completely randomized design. The L.casei TH14 additive (L) was factor A. Factor B was the molasses additive (M), while factor C was urea (U). There was no interaction effect of L, U, and M on gas production, volatile fatty acid (VFA) content, pH value, or ammonia-nitrogen level (P<0.05). The interaction of L, U, and M influenced in vitro dry matter digestibility (IVDMD) at 12 h (P < 0.05), and the CSVP fermented with the additions of L, U, and M together (LUM) was higher than the additions of CON, M, U, UM, and L on IVDMD (P < 0.05). However, the IVDMD values of adding LUM were higher in the control group (CON), M, U, UM, and L additive groups (P < 0.05). There was an interaction effect of L, U, and M on the protozoal count at 8 h (P<0.05), which had a lower protozoal count in the control group. In addition, acetic acid and butyric acid concentrations at 4 h and 8 h (P<0.05) were increased during the fermentation of CSVP using L and M combinations. Furthermore, the combination of U and M enhanced (P<0.05) average acetic acid, propionic acid, and pH at 4 h and 8 h while reducing (P<0.05) the gas generation from the insoluble portion (b). It was suggested that utilizing L. casei TH14 together with urea and molasses can enhance nutrient contents and improve the in vitro dry matter digestibility of CSVP, although it has no effect on ruminal fermentation or gas production.

Effect of Replacing Corn Meal with Winged Bean Tuber (Psophocarpus tetragonolobus) Pellet on Gas Production, Ruminal Fermentation, and Degradability Using In Vitro Gas Technique

The objective of this study is to evaluate the effects of replacing corn meal in ruminant diets with winged bean (Psophocarpus tetragonolobus) tubers (WBT) on ruminal fermentation, gas production parameters, and in vitro degradability. The study employed a completely random design (CRD) in its execution. The experimental design employed was a completely randomized design (CRD), featuring eleven levels of corn meal substitution with winged bean tubers pellet (WBTP) at 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%. The levels were grouped into four categories of replacement: control (0% in the diet), low levels (10%, 20%, and 30% in the diet), medium levels (40%, 50%, 60%, and 70% in the diet), and high levels (80%, 90%, and 100% in the diet). The experimental results indicated that substituting corn meal with WBTP at moderate and high levels in the diet could improve the performance of the fermentation process by increasing the gas production rate constant from the insoluble fraction (p < 0.01). The IVDMD exhibited a higher degree of in vitro degradation after 12 h (h), with the mean value being higher in the high group compared to the medium until the high group (p < 0.05). At the 4 h mark, the groups that substituted corn meal with WBTP exhibited a decrease in pH value (p < 0.05) in comparison to the control group. The substitution of corn meal with WBTP resulted in the lowest protozoal count after 8 h in the median group (p < 0.05). A significant difference in the effect of WBTP on total volatile fatty acid (TVFA) concentration was observed at 8 h after incubation (p < 0.05). The medium and high levels of WBTP replacement resulted in the lowest TVFA concentration at 8 h (p < 0.05). The mean proportion of acetic acid (C2) linearly declined and was lowest when a high level of WBTP replaced cornmeal (p < 0.05). The concentration of propionic acid (C3) at 8 h after incubation and average values were linearly significantly different when various levels of WBTP were utilized. Replacing corn meal with WBTP at a high level showed the highest concentration of C3. Moreover, substituting medium and high concentrations of WBTP for corn meal resulted in a significant reduction in both the C2:C3 ratio at 8 h and the mean value (p < 0.05). In conclusion, WBTP exhibits a nutritional composition that is advantageous and may be an energetic substitute for corn meal.

Feeding Pellets Containing Agro-Industrial Waste Enhances Feed Utilization and Rumen Functions in Thai Beef Cattle

The objective of this research was to investigate the effects of citric waste fermented with yeast waste pellet (CWYWP) supplementation on feed intake, rumen characteristics, and blood metabolites in native Thai beef cattle that are fed a rice-straw-based diet. Four native male Thai beef cattle (1.0-1.5 years old) with an initial body weight (BW) of 116 ± 16 kg were held in a 4 × 4 Latin square design within 21-day periods. The animals were assigned to receive CWYWP supplementation at 0%, 2%, 4%, and 6% of the total dry matter (DM) intake per day. The results indicate that feeding beef cattle with CWYWP leads to a linear increase in the total intake as well was the intake of crude protein (CP) and the digestibility of CP, with the maximum levels observed at 6% CWYWP supplementation (p < 0.05). Rumen characteristics, including pH, blood urea-nitrogen concentration, and protozoal population, showed no significant alterations in response to the varying CWYWP dosages (p > 0.05). In addition, the CWYWP supplementation resulted in no significant changes in the concentration of ammonia-nitrogen, remaining within an average normal range of 10.19-10.38 mg/dL (p > 0.05). The inclusion of 6% CWYWP resulted in the highest population of ruminal bacteria (p < 0.05). Additionally, the CWYWP supplementation led to a statistically significant increase in the mean propionic acid concentration as compared to the group that did not receive the CWYWP supplementation (p < 0.05). In conclusion, this experiment demonstrates that supplementing Thai native beef cattle with CWYWP at either 4% or 6% DM per day can enhance their total CP intake as well as the CP digestibility and rumen bacterial population, and can increase propionate concentration.

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.

Recycling of Citric Acid Waste for Potential Use as Animal Feed through Fermentation with Lactic Acid Bacteria and a Mixture of Fibrolytic Enzymes

Once improperly managed, the citric acid production industry generates waste, which contributes to pollution and other environmental issues. We proposed that, with sufficient quality improvement, citric acid by-product (CAP) might be used for animal feed, thereby reducing the environmental impact. The aim of the present study was to ferment citric acid by-product (CAP) by inoculation with lactic acid bacteria (LAB) and a fibrolytic enzyme mixture for quality improvement and crude fiber reduction in the waste products. LAB inoculants were L. casei TH14, and the additive enzyme used was a fibrolytic enzyme mixture (glucanase, pectinase, and carboxymethylcellulase) of a small-scale fermentation method. The seven treatments employed in this study were as follows: (1) control (untreated), (2) CAP-inoculated L. casei TH14 at 0.01% DM, (3) CAP-inoculated L. casei TH14 at 0.05% DM, (4) CAP-inoculated enzymes at 0.01% DM, (5) CAP-inoculated enzymes at 0.05% DM, (6) CAP-inoculated L. casei TH14 at 0.01% DM with enzymes at 0.01% DM, and (7) CAP-inoculated L. casei TH14 at 0.05% DM with enzymes at 0.05% DM. The samples were taken on days 1, 7, 14, 21, and 28 of ensiling, both before and after. Four replications were used. The results of the chemical composition of the CAP before and after ensilage inoculated with L. casei TH14 did not show any differences in crude protein, ether extract, ash, or gross energy, but the enzymes significantly (p < 0.05) decreased crude fiber and increased nitrogen-free extract. The combination was especially effective at improving the characteristics of CAP, with a reduction in crude fiber from 21.98% to 22.69%, of neutral detergent fiber (NDF) from 16.01% to 17.54%, and of acid detergent fiber (ADF) from 13.75% to 16.19%. Furthermore, the combination of L. casei TH14 and the enzyme increased crude protein from 1.75% to 2.24% at 28 days of ensiling. Therefore, CAP-inoculated L. casei TH14 did not change in chemical composition, while crude fiber, NDF, and ADF decreased when CAP was inoculated with enzyme. The combination of L. casei TH14 and the enzyme is more effective at improving chemical composition and reducing crude fiber and enhancing carbohydrate breakdown in the CAP. Finally, by enhancing the CAP’s quality, it may be possible to use it in animal feed and minimize its impact on the environment.

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.

Starch Properties, Nutrients Profiles, In Vitro Ruminal Fermentation and Molecular Structure of Corn Processed in Different Ways

Processing will improve the digestion of corn by ruminant animals. The objectives of this study were to investigate the effects of processing methods (grinding, G; steam flaking, SF; extrusion, E) on the starch properties, nutrient profiles, in vitro ruminal fermentation and molecular structure of corn. Compared with G, SF and E increased (p < 0.05) the starch content, starch gelatinization, ruminal gas production (GP, 0.5–32 h), propionic acid, starch degradability (SD), the area and height of carbohydrate peaks, and decreased (p < 0.05) starch crystallinity, content of crude protein, neutral detergent fiber and acid detergent fiber, ruminal NH3-N, the area and height of amide I and II, α-helix, and β-sheet. The total VFA (24 h, 48 h) tended to be increased by SF and E (p < 0.10). The carbohydrate peak area and height were positively (p < 0.05) correlated with GP (1–24 h) and SD. The protein molecular absorption intensity was negatively correlated with SD (p < 0.05). The change in starch properties, GP (1–24 h) and molecular structure caused by E was greater than SF (p < 0.05). These results indicated that the higher starch gelatinization and lower starch crystallinity of E corn, induced by the high temperature and pressure, enabled more fermentation and digestion in the artificial rumen. The carbohydrate and protein molecular structures were correlated with the nutritional characteristics of corn.

A Meta-Analysis of Essential Oils Use for Beef Cattle Feed: Rumen Fermentation, Blood Metabolites, Meat Quality, Performance and, Environmental and Economic Impact

The objective of this study was to see how dietary supplementation with essential oils (EOs) affected rumen fermentation, blood metabolites, growth performance and meat quality of beef cattle through a meta-analysis. In addition, a simulation analysis was conducted to evaluate the effects of EOs on the economic and environmental impact of beef production. Data were extracted from 34 peer-reviewed studies and analyzed using random-effects statistical models to assess the weighted mean difference (WMD) between control and EOs treatments. Dietary supplementation of EOs increased (p < 0.01) dry matter intake (WMD = 0.209 kg/d), final body weight (WMD = 12.843 kg), daily weight gain (WMD = 0.087 kg/d), feed efficiency (WMD = 0.004 kg/kg), hot carcass weight (WMD = 5.45 kg), and Longissimus dorsi muscle area (WMD = 3.48 cm2). Lower (p < 0.05) ruminal concentration of ammonia nitrogen (WMD = −1.18 mg/dL), acetate (WMD = −4.37 mol/100 mol) and total protozoa (WMD = −2.17 × 105/mL), and higher concentration of propionate (WMD = 0.878 mol/100 mol, p < 0.001) were observed in response to EOs supplementation. Serum urea concentration (WMD = −1.35 mg/dL, p = 0.026) and haptoglobin (WMD = −39.67 μg/mL, p = 0.031) were lower in cattle supplemented with EOs. In meat, EOs supplementation reduced (p < 0.001) cooking loss (WMD = −61.765 g/kg), shear force (WMD = −0.211 kgf/cm2), and malondialdehyde content (WMD = −0.040 mg/kg), but did not affect pH, color (L* a* and b*), or chemical composition (p > 0.05). Simulation analysis showed that EOs increased economic income by 1.44% and reduced the environmental footprint by 0.83%. In conclusion, dietary supplementation of EOs improves productive performance and rumen fermentation, while increasing the economic profitability and reducing the environmental impact of beef cattle. In addition, supplementation with EOs improves beef tenderness and oxidative stability.

The Effects of Selenium on Rumen Fermentation Parameters and Microbial Metagenome in Goats

This study evaluated the effects of selenium yeast (SY) on rumen fermentation parameters, rumen bacterial diversity, and expression pathways in goats. A total of 18 Qianbei-pockmarked weather goats from Guizhou (body weight, 25.75 ± 1.75 kg; mean ± standard deviation) were assigned to three groups according to a completely randomized design. Control group (CON, n = 6) kids were fed a basal diet, while treatment 1 (LS, n = 6) and treatment 2 (HS, n = 6) kids were fed a basal diet with 2.4 and 4.8 mg/kg SY, respectively. The feeding trial lasted for 74 days. The results indicated that the ruminal fluid of LS goats had significantly higher levels of propionic, caproic, isobutyric, and isovaleric acids than that of the CON. The levels of butyric and valeric acids were higher in the HS group than in the CON. The acetate:propionate ratio was significantly higher in the CON than in the two treatments. In addition, the inclusion of 2.4 mg/kg SY can lead to a significant decrease in the relative abundances of Euryarchaeota, and Proteobacteria at the phylum level compared to the CON and the HS groups. At the genus level, the LS group had a significant decrease in the relative abundance of Methanobrevibacter and Sarcina, whereas it could lead to a significant increase in the relative abundance of Clostridium in the ruminal fluid relative of the other two groups. At the species level, the LS group had a significant decrease in the relative abundance of bacterium_P3, bacterium_P201, and Sarcina_sp._DSM_11001 compared to the other groups. Moreover, the CON group had a significant decrease in the relative abundance of bacterium_P201 compared to the other two treatments. Compared to the CON, the addition of 2.4 mg/kg SY significantly enriched carbohydrate metabolism pathways in the ruminal fluid for gene encoding. Additionally, goats receiving SY showed a significant upregulation of glycosyl transferase and carbohydrate binding module pathways. These results suggest that dietary supplementation with SY modulates fermentation parameters, and it affects microbial diversity and microbial metagenome in the rumen of Qianbei-pockmarked goats.

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

Simple Summary

As a result of the recent ban on antibiotics in feed, animal probiotics are becoming increasingly popular. Yeast is extensively used as both a probiotic and prebiotic in the gastrointestinal tracts of ruminants. The purpose of this study is to determine how adding yeast (Saccharomyces cerevisiae) to the diet and changing the roughage-to-concentrate ratio (R:C ratio) affects nutrient consumption, rumen fermentation, microbial protein synthesis, and protozoal population in Thai native beef cattle. The roughage source was urea–calcium-hydroxide-treated rice straw. The findings suggest that supplementing with a R:C ratio of 40:60 and a LY of 4 g/hd/d boosted nutrient digestibility, volatile fatty acid (VFA) production, propionic acid (C₃) in particular, and microbial protein synthesis while lowering protozoal population.

Abstract

The objective of this research is to investigate the effect of yeast (Saccharomyces cerevisiae) adding and roughage-to-concentrate ratio (R:C ratio) on nutrients utilization, rumen fermentation efficiency, microbial protein synthesis, and protozoal population in Thai native beef cattle. Four Thai native beef cattle, weighing an average of 120 ± 10 kg live weight, were randomly assigned to four dietary treatments using a 2 × 2 factorial arrangement in a 4 × 4 Latin square design. Factor A was the level of roughage-to-concentrate ratio (R:C ratio) at 60:40 and 40:60; factor B was the levels of live yeast (LY) supplementation at 0 and 4 g/hd/d; urea–calcium-hydroxide-treated rice straw were used as a roughage source. Findings revealed that total intake and digestibility of dry matter (DM), organic matter (OM), and crude protein (CP) were increased (p < 0.05) by both factors, being greater for steers fed a R:C ratio of 40:60 supplemented with 4 g LY/hd/d. Ruminal ammonia nitrogen, total volatile fatty acid (VFA), and propionate (C₃) were increased (p < 0.05) at the R:C ratio of 40:60 with LY supplementation at 4 g/hd/d, whereas rumen acetate (C₂) and the C₂ to C₃ ratio were decreased (p < 0.05). With a high level of concentrate, LY addition increased total bacterial direct counts and fungal zoospores (p < 0.05), but decreased protozoal populations (p < 0.05). High-concentrate diet and LY supplementation increased nitrogen absorption and the efficiency of microbial nitrogen protein production. In conclusion, feeding beef cattle with 4 g/hd/d LY at a R:C ratio of 40:60 increased C₃ and nutritional digestibility while lowering protozoal population.

Mitragyna speciosa Korth Leaves Supplementation on Feed Utilization, Rumen Fermentation Efficiency, Microbial Population, and Methane Production In Vitro

The objective of the research was to evaluate the different levels of Mitragyna speciosa Korth leaves powder (MSLP) added to rations with 60:40 or 40:60 roughage to a concentrate (R:C ratio) on in vitro nutrient digestibility, rumen fermentation characteristics, microbial population, and methane (CH4) production. The treatments were arranged according to a 2 × 8 factorial arrangement in a completely randomized design. The two factors contain the R:C ratio (60:40 and 40:60) and the levels of MSLP addition (0, 1, 2, 3, 4, 5, 6, and 7% of the total substrate). There was no interaction between the R:C ratio and MSLP supplementation on gas production kinetics, ammonia nitrogen (NH3-N), and microbial populations. The gas production rate constant for the insoluble fraction (c) was increased by the R:C ratio at (40:60), whilst there was no difference obtained among treatments for cumulative gas production, whilst the gas production rate constant for the insoluble fraction (c) was increased by the R:C ratio at 40:60. The concentration of NH3-N was influenced by the R:C ratio and MSLP addition both at 4 and 8 h after incubation. In vitro dry matter degradability (IVDMD) and organic matter degradability (IVOMD) were significantly improved by the R:C ratio and supplementation of MSLP at 12 h. Increasing the R:C ratio and MSLP concentrations increased total volatile fatty acid (VFA) and propionic acid (C3) concentrations while decreasing acetic acid (C2) and butyric acid (C4) concentrations; thus, the C2:C3 ratio was reduced. MSLP addition reduced protozoa and methanogen populations (p < 0.05). The calculated CH4 production was decreased (p < 0.05) by the R:C ratios at 40:60 and supplementation of MSLP. Finally, the addition of MSLP as a phytonutrient may improve nutrient degradability and rumen fermentation properties while decreasing protozoa, methanogen population, and CH4 production.

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.

Manipulation of In Vitro Ruminal Fermentation and Feed Digestibility as Influenced by Yeast Waste-Treated Cassava Pulp Substitute Soybean Meal and Different Roughage to Concentrate Ratio

Cassava pulp (CS) is high in fiber and low in protein; hence, improving the nutritive value of CS is required to increase its contribution to enhancing ruminant production. The present work hypothesized that CS quality could be enhanced by fermentation with yeast waste (YW), which can be used to replace soybean meal (SBM), as well as lead to improved feed utilization in ruminants. Thus, evaluation of in vitro ruminal fermentation and feed digestibility, as influenced by YW-treated CS and different roughage (R) to concentrate (C) ratios, was elucidated. The design of the experiment was a 5 × 3 factorial arrangement in a completely randomized design. Each treatment contained three replications and three runs. The first factor was replacing SBM with CS fermented with YW (CSYW) in a concentrate ratio at 100:0, 75:25, 50:50, 25:75, and 0:100, respectively. The second factor was R:C ratios at 70:30, 50:50, and 30:70. The level of CSYW showed significantly higher (p < 0.01) gas production from the insoluble fraction (b), potential extent of gas production (a + b), and cumulative gas production at 96 h than the control group (p < 0.05). There were no interactions among the CSYW and R:C ratio on the in vitro digestibility (p > 0.05). Furthermore, increasing the amount of CSYW to replace SBM up to 75% had no negative effect on in vitro neutral detergent fiber degradability (IVNDFD) (p > 0.05) while replacing CSWY at 100% could reduce IVNDFD (p > 0.05). The bacterial population in the rumen was reduced by 25.05% when CSYW completely replaced SBM (p < 0.05); however, 75% of CSWY in the diet did not change the bacterial population (p > 0.05). The concentration of propionate (C3) decreased upon an increase in the CSYW level, which was lowest with the replacement of SBM by CSYW up to 75%. However, various R:C ratios did not influence total volatile fatty acids (VFAs), and the proportion of VFAs (p > 0.05), except the concentration of C3, increased when the proportion of a concentrate diet increased (p < 0.05). In conclusion, CSYW could be utilized as a partial replacement for SBM in concentrate diets up to 75% without affecting gas kinetics, ruminal parameters, or in vitro digestibility.