Roughage to Concentrate Ratio and Saccharomyces cerevisiae Inclusion Could Modulate Feed Digestion and In Vitro Ruminal Fermentation

Abstract

The objective of this research was to investigate the effect of the roughage-to-concentrate (R:C) ratio and the addition of live yeast (LY) on ruminal fermentation characteristics and methane (CH4) production. The experimental design was randomly allocated according to a completely randomized design in a 4 × 4 factorial arrangement. The first factor was four rations of R:C at 80:20, 60:40, 40:60, and 20:80, and the second factor was an additional four doses of Saccharomyces cerevisiae (live yeast; LY) at 0, 2.0 × 106, 4.0 × 106, and 6.0 × 106 colony-forming unit (cfu), respectively. For the in vitro method, during the incubation, the gas production was noted at 0, 1, 2, 4, 6, 8, 10, 12, 18, 24, 48, 72, and 96 h. The rumen solution mixture was collected at 0, 4, 8, 12, and 24 h of incubating after inoculation. Cumulative gas production at 96 h was highest in the R:C ratio, at 20:80, while the addition of LY improves the kinetics and accumulation of gas (p > 0.05). Maximum in vitro dry matter digestibility (IVDMD) and in vitro organic matter digestibility (IVOMD) at 24 h after incubation were achieved at the R:C ratio 20:80 and the addition of LY at 6 × 106 cfu, which were greater than the control by 13.7% and 12.4%, respectively. Ruminal pH at 8 h after incubation decreased with an increased proportion of concentrates in the diet, whereas it was lowest when the R:C ratio was at 20:80. Increasing the proportion of a concentrate diet increased total volatile fatty acid (TVFA) and propionic acid (C3), whereas the acetic acid (C2) and C2-to-C3 ratios decreased (p < 0.05). TVFA and C3 increased with the addition of LY at 6 × 106 cfu, which was greater than the control by 11.5% and 17.2%, respectively. No interaction effect was observed between the R:C ratio and LY on the CH4 concentration. The calculated ruminal CH4 production decreased with the increasing proportion of concentrates in the diet, particularly the R:C ratio at 20:80. The CH4 production for LY addition at 6 × 106 cfu was lower than the control treatment by 17.2%. Moreover, the greatest populations of bacteria, protozoa, and fungi at 8 h after incubation were found with the addition of LY at 6 × 106 cfu, which were higher than the control by 19.0%, 20.7%, and 40.4%, respectively. In conclusion, a high ratio of roughage and the concentrate and addition of LY at 6.0 × 106 cfu of the total dietary substrate could improve rumen fermentation, improve feed digestibility, and reduce the CH4 production.

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

“…Major alterations of CH 4 in ruminants are produced through propionate fermentation, and CH 4 production decreased with yeast supplementation. This result concurred with Phesatcha et al [11] and Wang et al [34], who found that CH 4 production decreased with yeast supplementation, while Munoz et al [35] observed that DY supplementation increased CH 4 production in lactating dairy cows and Bayat et al [36] determined that yeast did not influence CH 4 emissions. Diverse effects of yeast supplementation on CH 4 synthesis were attributed to varying yeast strains, dosages, and diets utilized in the trials [28].…”

“…Ruminal pH and temperature values for all DY supplementations were reported in the optimal range by Phesatcha et al [11]. In general, rumen pH stability benefits acid-sensitive cellulolytic bacteria and is extremely beneficial to beef cattle, especially fattening cattle.…”

“…The rice straw-treated urea-calcium hydroxide was made by adding 2 kg of urea and 2 kg of Ca(OH) 2 in 100 L to 100 kg of rice straw. The quantity of urea and calcium hydroxide solution was sprayed onto rice straw bales and then covered with a sheet of plastic for at least 10 days before feeding to the beef cattle [11]. The animals were dewormed and given a 14-day acclimation period prior to the experiment.…”

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

“…This agrees with Cherdthong et al [40], who revealed that the addition of a high-concentrated diet supplied an enhanced proportion of C3. Furthermore, the C3 content could significantly increase when a substrate containing 80% of the concentrate was tested [35].…”

“…The increased fermentable substrate (sugar and starch) in the concentrate diet may have favored the growth of bacteria and protozoa, resulting in a change in the structure and diversity of microbial populations [34]. Accordingly, Phesatcha et al [35] also noticed an enhancement in the total amount of ruminal bacteria, with a comparable shift in rumen microbial population numbers in animals that were fed a high-concentrate diet versus animals that were fed a low-concentrate diet vs. those fed a low level of concentrate diet. This demonstrated that, when a rapid fermentation carbohydrate is supplied, microbial bacteria in the rumen tend to be enhanced.…”