Effect of red osier dogwood extract on in vitro gas production, dry matter digestibility, and fermentation characteristics of forage-based diet or grain-based diet

This in vitro batch culture study investigated the effects of red osier dogwood (ROD) extract supplementation on gas production (GP), dry matter disappearance (DMD), and fermentation characteristics in high forage (HF) and high grain (HG) diets with varying media pH level. The experiment was a factorial arrangement of treatments in a completely randomized design with 2 media pH (5.8 and 6.5) × 4 dose rates of ROD extract (0, 1, 3, and 5% of DM substrate). An additional treatment of monensin was added as a positive control for each pH level. The HF substrate consisted of 400 and 600 g/kg DM barley-based concentrate and barley silage, respectively, while the HG substrate contained 100 and 900 g/kg DM barley silage and barley-based concentrate, respectively. Treatments were incubated for 24 h with GP, DMD and fermentation parameters determined. No interaction was detected between the media pH level and ROD extract dose rate on GP, DMD and most of the fermentation parameters. The GP, DMD, and total volatile fatty acid (VFA) concentration were greater (P = 0.01) with media pH of 6.5 in both HF and HG diets. The GP were not affected by increasing ROD dose rate, except that GP linearly decreased in the HF (P = 0.04) and HG (P = 0.01) diets at 24 h; the DMD tended to linearly decrease at pH 6.5 (P = 0.06) for both HF and HG diets and at pH 5.8 (P = 0.02) for the HG diet. Adding ROD extract to the HF and HG diets linearly (P = 0.01) increased the acetate molar proportion at high or low media pH and consequently, the acetate to propionate (A:P) ratio linearly (P ≤ 0.04) increased. Supplementation of ROD extract to the HF diet linearly (P = 0.04) decreased the molar proportion of propionate at pH 6.5 (interaction between pH and ROD extract; P = 0.05), but had no effect on propionate proportion when added to the HG diet. Moreover, the proportion of branched-chain fatty acids linearly (P = 0.03) decreased with ROD extract supplementation at low pH (interaction, P < 0.05) for HF diet and linearly decreased (P = 0.05) at pH 6.5 for HG diet (interaction, P < 0.05). The NH3-N concentration was not affected by ROD supplementation in the HF diet but it linearly (P = 0.01) decreased with increasing dose rate in the HG diet. Methane concentration tended to linearly (P = 0.06) increase with ROD extract supplementation at high pH for HF diet and linearly increased at pH 5.8 (P = 0.06) and pH 6.5 (P = 0.02) for HG diet. These results indicate that the decreased DMD and increased A:P ratio observed with addition of ROD extract may be beneficial to HG-fed cattle to reduce the risk of rumen acidosis without negatively impacting fiber digestion.

The gas production, ruminal fermentation parameters, and microbiota in response to Clostridium butyricum supplementation on in vitro varying with media pH levels

The aim of this study was to investigate the gas production (GP), dry matter disappearance (DMD), fermentation parameters, and rumen microbiota in response to Clostridium butyricum (CB) supplementation in batch culture using a high forage substrate. The doses of CB were supplemented at 0 (Control), 0.5 × 10⁶, 1 × 10⁶, and 2 × 10⁶  CFU/bottle, respectively, at either media pH 6.0 or pH 6.6. The 16S rRNA gene sequencing was used to detect the microbiota of fermentation culture in control and 1 × 10⁶  CFU/bottle after 24 h of incubation. The results showed that the GP (p < 0.001), DMD (p = 0.008), total volatile fatty acid (VFA) concentration (p < 0.001), acetate to propionate ratio (p < 0.001), and NH₃-N concentration (p < 0.001) were greater at media pH 6.6 than pH 6.0. Furthermore, the linearly increased DMD (pH 6.0, p = 0.002; pH 6.6, p < 0.001) and quadratically increased butyrate proportion (pH 6.0, p = 0.076; pH 6.6, p < 0.053) and NH₃-N concentration (pH 6.0, p = 0.003; pH 6.6, p = 0.014) were observed with increasing doses of CB. The Alpha diversity indexes of OTU number and Chao1 were higher (p = 0.045) at media pH 6.6 than pH 6.0, but they were not affected by CB supplementation. The PCoA analysis (unweighted uniFrac) demonstrated that the clustering of the bacterial microbiota of control and CB were distinctly separated from each other at media pH 6.0. At the phylum level, the abundance of Bacteroidota (p < 0.001) decreased, whereas that of Firmicutes (p = 0.026) increased when the media pH was elevated from 6.0 to 6.6. Supplementation of CB increased relative abundances of Rikenellaceae_RC9_gut_group (p = 0.002), Christensenellaceae_R-7_group (p < 0.001), and NK4A214_group (p = 0.002) at genus level. Interactions between media pH and CB addition were observed for bacteria at both phylum and genus levels. These results indicated that increasing the media pH level and CB supplementation increased in vitro rumen digestibility, and altered the ruminal fermentation pattern (by media pH) and microbiota.

Effect of Clostridium butyricum Supplementation on in vitro Rumen Fermentation and Microbiota With High Grain Substrate Varying With Media pH Levels

Clostridium butyricum (C. butyricum) can survive at low pH, and it has been widely used as an alternative to antibiotics for the improvement of feed efficiency and animal health in monogastrics. A recent study suggested that the improved ruminal fermentation with supplementing C. butyricum is may be associated with increasing the abundance of rumen microbiota in Holstein heifers, as ruminal pH plays a key role in rumen microbiota and the probiotics are often active in a dose-dependent manner. The objective of this study was to determine the effects of increasing the doses of C. butyricum on gas production (GP) kinetics, dry matter disappearance (DMD), fermentation characteristics, and rumen microbiota using a high grain substrate in batch culture varying with media pH levels. The doses of C. butyricum were supplemented at 0 (control), 0.5 × 106, 1 × 106, and 2 × 106 CFU/bottle, respectively, at either media pH 6.0 or pH 6.6. The fermentation microbiota at 0 and 1 × 106 CFU/bottle were determined using the 16S rRNA high throughput sequencing technology. Overall, the GP, DMD, total volatile fatty acid (VFA) concentration, and the ratio of acetate:propionate were higher (P <0.01) at media pH 6.6 than at pH 6.0. However, there was interaction between pH × dose of C. butyricum for rate constant of GP (P = 0.01), average GP rate (P = 0.07), and volume of GP (P = 0.06); with the increase in C. butyricum supplementation, the GP kinetics were not changed at media pH 6.0, but the volume (P = 0.02), rate of GP (P = 0.01), and average GP rate (P = 0.01) were quadratically changed at media pH 6.6. The DMD was not affected by increasing the supplementation of C. butyricum. The molar proportions of propionate (P <0.09), butyrate (P <0.06), and NH3-N concentration (P = 0.02) were quadratically changed with increasing supplementation of C. butyricum regardless of media pH levels. The interactions between media pH level and dose of C. butyricum supplementation were noticed for alpha diversity indexes of Shannon (P = 0.02) and Evenness (P = 0.04). The alpha diversity indexes increased (P <0.05) except for Chao1 with supplementation of C. butyricum. The unweighted uniFrac analysis showed that the group of control at media pH 6.0 and control at media pH 6.6, and supplementation of C. butyricum and control at media pH 6.0 clustered separately from each other. At the phylum level, relative abundance (RA) of Bacteroidota was lower (P <0.01) and Firmicutes was higher (P <0.01) at media pH 6.6 than pH 6.0. Moreover, RA of Proteobacteria decreased (P <0.05) with supplemented C. butyricum at either media pH 6.6 or pH 6.0. At media pH 6.6, RA of Rikenellaceae_RC9_gut_group and Prevotella were decreased, and CAG-352 was increased (at genus level) compared to pH 6.0. Supplementation of C. butyricum decreased RA of Rikenellaceae_RC9_gut_group and increased CAG-352 at media pH 6.0. It could hence be concluded that manipulating media pH level and supplementation of C. butyricum effectively modulated in vitro rumen fermentation characteristics and microbiota but in a dose depending manner of C. butyricum addition.

The effects of feeding benzoic acid and/or live active yeast (Saccharomyces cerevisiae) on beef cattle performance, feeding behavior, and carcass characteristics

Fifty-nine Angus-cross finishing steers were used to evaluate benzoic acid, active dry yeast (Saccharomyces cerevisiae), or a combination of benzoic acid and active dry yeast when supplemented in a high-grain finishing diet on live animal performance, feeding behavior, and carcass characteristics. Steers were fed a high-grain diet for the final 106 d of finishing. Treatments were as follows: no additional supplementation (CON), 0.5% benzoic acid (ACD), 3 g per head per day active dry S. cerevisiae (YST), or both 0.5% benzoic acid and 3 g/head per day S. cerevisiae (AY). Steers were weighed every 14 d, and ultrasound was performed for rib and rump fat thickness at the beginning (day 1), middle (day 57), and end (day 99) of the experiment. Insert feeding stations were used to collect individual feeding behavior data and DMI daily throughout. Blood samples were collected on days 21 and 22 and days 99-101 to assess plane of nutrition and metabolism. Ruminal fluid samples were collected by oral gavage 4 wk prior to slaughter. Carcass characteristics were examined at a federally inspected slaughter facility. Data were analyzed using PROC GLIMMIX of SAS with initial body weight (BW) as a covariate. Benzoic acid supplementation increased (P = 0.002) overall dry matter intake (DMI) compared to YST and CON steers, which may be due to a faster eating rate (P ≤ 0.008). Animal performance parameters (BW, average daily gain, feed conversion, and ultrasound fat depth) were not different (P ≥ 0.11) among treatment groups. Aspartate aminotransferase concentration was greatest (P ≤ 0.01) for YST steers, which may have been reflected in numerically greater liver abscesses. Carcass traits did not differ (P ≥ 0.33) among treatment groups. Ruminal pH was greater (P = 0.006) for ACD steers than AY steers (pH of 6.16 vs. 5.66, respectively), which indicated that there may be an interactive effect between benzoic acid and active dry yeast. To summarize, steers fed a high-grain finishing diet supplemented with benzoic acid, active dry yeast, or both benzoic acid and active dry yeast had similar growth performance and carcass characteristics compared to those without supplementation. However, the addition of benzoic acid alone increased DMI, variation in DMI, eating rate, and ruminal pH. Future studies are warranted to further investigate the impacts of benzoic acid on the ruminal environment of feedlot cattle.

Ruminal pH pattern, fermentation characteristics and related bacteria in response to dietary live yeast (Saccharomyces cerevisiae) supplementation in beef cattle

Objective

In this study we aimed to evaluate the effect of dietary live yeast supplementation on ruminal pH pattern, fermentation characteristics and associated bacteria in beef cattle.

Methods

This work comprised of in vitro and in vivo experiments. In vitro fermentation was conducted by incubating 0%, 0.05%, 0.075%, 0.1%, 0.125%, and 0.15% active dried yeast (Saccharomyces cerevisiae, ADY) with total mixed ration substrate to determine its dose effect. According to in vitro results, 0.1% ADY inclusion level was assigned in in vivo study for continuously monitoring ruminal fermentation characteristics and microbes. Six ruminally cannulated steers were randomly assigned to 2 treatments (Control and ADY supplementation) as two-period crossover design (30-day). Blood samples were harvested before-feeding and rumen fluid was sampled at 0, 3, 6, 9, and 12 h post-feeding on 30 d.

Results

After 24 h in vitro fermentation, pH and gas production were increased at 0.1% ADY where ammonia nitrogen and microbial crude protein also displayed lowest and peak values, respectively. Acetate, butyrate and total volatile fatty acids concentrations heightened with increasing ADY doses and plateaued at high levels, while acetate to propionate ratio was decreased accordingly. In in vivo study, ruminal pH was increased with ADY supplementation that also elevated acetate and propionate. Conversely, ADY reduced lactate level by dampening Streptococcus bovis and inducing greater Selenomonas ruminantium and Megasphaera elsdenii populations involved in lactate utilization. The serum urea nitrogen decreased, whereas glucose, albumin and total protein concentrations were increased with ADY supplementation.

Conclusion

The results demonstrated dietary ADY improved ruminal fermentation dose-dependently. The ruminal lactate reduction through modification of lactate metabolic bacteria could be an important reason for rumen pH stabilization induced by ADY. ADY supplementation offered a complementary probiotics strategy in improving gluconeogenesis and nitrogen metabolism of beef cattle, potentially resulted from optimized rumen pH and fermentation.

Effect of mixed live yeast and lactic acid bacteria on in vitro fermentation with varying media pH using a high-grain or high-forage diet

Two experiments were conducted to assess the effects of media pH and mixtures (SCEF) of live yeast [Saccharomyces cerevisiae (SC)] and lactic acid bacteria [Enterococcus faecium (EF)] on gas production (GP), dry matter disappearance (DMD), and volatile fatty acid (VFA) concentrations in batch culture using either high-forage (HF) or high-grain (HG) diets. Diets were evaluated in separate experiments, each as a complete randomized design with 2 (media pH 5.8 and 6.5) × 5 (control, three SCEF, monensin) factorial arrangement of treatments. The SCEF had varying ratios of SC:EF: 0:0 (control), 1.18:1 (SCEF1), 1.25:1 (SCEF2), and 1.32:1 (SCEF3), added on a log10 basis. For the HF diet, supplementation of SCEF had greater GP (P = 0.03) at pH 6.5 and greater DMD (P = 0.03) and VFA concentration (P < 0.01) at pH 5.8 and 6.5 than control. For the HG diet, acetate:propionate (A:P) ratio at pH 6.5 was greater (P = 0.05) for SCEF than control. Increasing ratio of SC to EF in SCEF linearly (P < 0.01) decreased GP and DMD and linearly increased acetate percentage at pH 6.5. These results suggest that optimizing the SC:EF ratio in a mixture of SCEF can help improve rumen fermentation.

Screening of live yeast and yeast derivatives for their impact of strain and dose on in vitro ruminal fermentation and microbial profiles with varying media pH levels in high-forage beef cattle diet

BACKGROUND

Yeast products showed beneficial effects with respect to stabilizing ruminal pH, stimulating ruminal fermentation and improving production efficiency. Batch cultures were conducted to evaluate the effects of yeast products on gas production (GP), dry matter disappearance (DMD) and fermentation characteristics of high-forage substrate. The study was a two media pH (5.8 and 6.5) × five yeasts (three live yeasts, LY: LY1, LY2, LY3; two yeast derivatives, YD: YD4, YD5) × four dosages factorial arrangement, with monensin (Mon) assigned as a positive control.

RESULTS

Greater (P < 0.01) GP, DMD, volatile fatty acid (VFA) concentration, ratio of acetate to propionate (A:P) and copy numbers of Fibrobacter succinogenes and Ruminococcus flavefaciens were observed at pH 6.5 than at pH 5.8. The GP kinetics, DMD, VFA concentration, A:P and NH₃ -N concentration differed (P < 0.05) among yeasts but varied with media pH or yeast dosages. Increasing doses of LY3 linearly increased DMD (P < 0.04) and VFA concentration (P < 0.001) at media pH 5.8. The DMD linearly (P < 0.02) increased with increased addition of YD4 (pH 6.5) and YD5 (pH 5.8) and the ratio of A:P linearly decreased (P < 0.01) with the addition of YD4 or YD5 at pH 5.8. Overall greater (P < 0.05) GP, A:P (pH 5.8) and DMD (pH 6.5) were observed with yeast products than with Mon.

CONCLUSION

LY3 appeared to be an interesting candidate for improving rumen digestibility and fermentation efficiency, particularly at low media pH. YD4 or YD5 improved fermentation efficiency and can be potentially fed as an alternative to Mon. © 2019 Her Majesty the Queen in Right of Canada Journal of the Science of Food and Agriculture © 2019 Society of Chemical Industry.