Yeast-fermentation products are promising feed additives to enhance ruminal fermentation, improve feed efficiency and animal performance, and potentially mitigate enteric methane (CH4) emissions. This study aimed to evaluate the effects of supplementing a Saccharomyces cerevisiae fermentation-derived postbiotic on ruminal fermentation parameters, CH4 production, and nutrient utilization in beef steers consuming a high-grain diet. Six ruminally cannulated Angus crossbred steers (783 ± 29 kg of bodyweight) were used in a crossover design (42-d period), where they received a basal diet comprised of (dry matter [DM] basis) 65.9% cracked corn, 14.4% bermudagrass hay, 9.9% dry distillers grains plus solubles, 4.9% cottonseed hulls, and 4.9% of vitamin–mineral supplement. Each day, steers were individually fed a carrier of dry distillers’ grains plus solubles (250 g/d as fed) with one of the following treatments: CTL, carrier only; or SCFP, carrier plus 28 g/steer/d of a Saccharomyces cerevisiae fermentation-derived postbiotic (NaturSafe, Diamond V, Cedar Rapids, IA). Ruminal fermentation parameters, including pH, concentration of ammonia nitrogen (NH3-N), volatile fatty acids (VFA), total gas, CH4 production, and in vitro organic matter (OM) digestibility, were assessed using an ex vivo model. Additionally, in vivo measurements of pH, VFA, and NH3-N were conducted over 24 h, and apparent total tract digestibility was determined using collected feed and fecal samples. Data was analyzed as a crossover design including treatment, order, and period as fixed effects, and steer within order as a random effect. Supplementation with SCFP had no effect (P > 0.10) on the ruminal fermentation parameters assessed using the ex vivo model. Daily supplementation of SCFP in vivo showed no effect (P = 0.12) on ruminal pH or concentration of NH3-N; however, a decrease (P = 0.04) in concentration (mM) of total VFA was observed due to reduced concentration of propionate (P = 0.03) and butyrate (P < 0.01). The acetate to propionate ratio was greater (P = 0.02) in SCFP compared with CTL. Supplementation of SCFP resulted in a decrease (P < 0.01) in molar proportion (MP; mol/100 mol) of butyrate and tended to reduce (P = 0.09) MP of propionate, yet MP of acetate and valerate increased (P = 0.02). Apparent total tract digestibility of DM, OM, and starch increased (P < 0.05), with crude protein digestibility showing a tendency to increase (P = 0.08) with SCFP inclusion. Thus, supplementing SCFP at a rate of 28 g/animal/d altered ruminal fermentation in vivo and improved the digestibility in this study.

Garlic (Allium sativum) contains secondary compounds that are known to modify rumen fermentation parameters and decrease methane (CH₄) emissions. The objective was to evaluate the effects of increasing the inclusion levels and processing methods of garlic on in vitro fermentation and CH₄ production. Treatments were arranged in a randomized complete block design with a 2 × 3 × 2 + 1 factorial arrangement, where the main factors were the initial condition of garlic (intact or smashed), drying process (freeze-dried, oven-dried, or autoclaved), and garlic proportion in the diet (2.5 and 5%) and one control (without garlic supplementation). Incubations were conducted using corn silage and cotton-gin trash (80:20, respectively) as basal substrates on three different days. Final pH, the concentration of volatile fatty acids (VFA) and ammonia nitrogen (NH₃-N), in vitro organic matter digestibility (IVOMD), total gas production, and CH₄ concentration were determined after 24 h. Initial garlic condition or drying processing neither modify (p > 0.05) the in vitro fermentation nor the CH₄ production. However, increasing garlic inclusion linearly increased (p < 0.05) IVOMD, the concentration of the total VFA, and the proportion of propionate. Also, the concentration of NH₃-N and the proportion of acetate increased quadratically (p < 0.05) with greater garlic inclusions. Finally, garlic inclusion did not affect (p > 0.05) gas and CH₄ production. In conclusion, increasing garlic levels, but not the processing methods, improved in vitro fermentation but did not modify CH₄ emissions under in vitro conditions.

The beef industry contributes to greenhouse gas emissions through enteric methane emissions, exacerbating climate change. Anacardic acid in cashew nutshell extract (CNSE), saponins and tannins (ST) are plant secondary metabolites that show promise in methane mitigation via antimicrobial effects, potentially exerting changes in ruminal fermentation patterns. This study examined the impact of CNSE, ST, and their combination on methane emissions, digestibility, intake, and performance of sixteen Angus crossbred steers (347 ± 30 kg) receiving a backgrounding diet (70:30 corn silage: cottonseed burrs). The study used a 4 × 4 Latin square design (4 steers, 4 treatments, 4 periods) with a 2 × 2 factorial arrangement, including the main effects of additive (CNSE or ST) fed individually or combined. Thus, steers received the following treatments: (1) no additive, (2) CNSE only, (3) ST only, or (4) both (CNSEST). Non-supplemented steers registered eight more feedbunk visits/d than ST-steers and spent an extra 10 min/d on the feedbunk. The addition of ST tended to increase dry matter, organic matter, and neutral detergent fiber intake. Additives fed individually reduced CP digestibility. Intake of the carrier containing CNSE only was lesser and coincided with a greater methane yield in that treatment. Digestibility and methane mitigation were improved after CNSEST compared with individual inclusion, suggesting synergistic reactions enhanced methane mitigation effects in fibrous diets without affecting the digestibility of nutrients nor animal growth performance.

Objective: To evaluate the effects of glucoamylase on ruminal in situ and in vitro dry matter degradability (IVDMD), in vitro starch degradability (IVSD), volatile fatty acids (VFA), gas production and methane production using cereal grains as substrates in beef cattle.Methods: Six substrates (4 mm; 0.70 g per F57 bag) including sorghum (micronized and whole), barley (whole and steam-flaked), and corn (dry-rolled and steam-flaked); were incubated with exogenous glucoamylase (from Trichoderma reesei; 0.25 mg/g substrate dry matter [DM]) and buffered rumen fluid in six replicates per run in 3 independent runs. IVDMD, IVSD, in situ DMD (ISDMD), VFA, and methane production was measured after 7, and 12 h of incubation. ISDMD was measured after 0, 1, 3, 7, and 12 h of ruminal incubation in beef cattle fed high grain diets.Results: Exogenous glucoamylase increased IVDMD and gas production for all substrates except whole sorghum and barley while ISDMD was increased for all substrates except whole barley. Glucoamylase increased IVSD for steam flaked barley and corn. Glucoamylase supplementation increased molar proportion of propionate and decreased acetate-to-propionate ratio, regardless of substrates used. Similarly, glucoamylase supplementation increased methane production with steam-flaked corn.Conclusion: Glucoamylase supplementation can potentially improve DM and starch degradability in cereal grains commonly used as ingredients in beef cattle diets.