Cricket (Gryllus bimaculatus) meal pellets as a protein supplement to improve feed efficiency, ruminal fermentation and microbial protein synthesis in Thai native beef cattle.

OBJECTIVE: Replacing soybean meal (SBM) with cricket (Gryllus bimaculatus) meal pellets (CMP) in concentrate diets was investigated for feed efficiency, ruminal fermentation and microbial protein synthesis in Thai native beef cattle. METHODS: Four male beef cattle were randomly assigned to treatments using a 4×4 Latin square design with four levels of SBM replaced by CMP at 0%, 33%, 67%, and 100% in concentrate diets. RESULTS: Results revealed that replacement of SBM with CMP did not affect dry matter (DM) consumption, while digestibilities of crude protein, acid detergent fiber and neutral detergent fiber were significantly enhanced (p<0.05) but did not alter digestibility of DM and organic matter. Increasing levels of CMP up to 100% in concentrate diets increased ruminal ammoniacal nitrogen (NH3-N) concentrations, blood urea nitrogen, total volatile fatty acids and propionate concentration (p<0.05), whereas production of methane and protozoal populations decreased (p<0.05). Efficiency of microbial nitrogen protein synthesis increased when SBM was replaced with CMP. CONCLUSION: Substitution of SBM with CMP in the feed concentrate mixture at up to 100% resulted in enhanced nutrient digestibility and rumen fermentation efficiency, with increased volatile fatty acids production, especially propionate and microbial protein synthesis, while decreasing protozoal populations and mitigating rumen methane production in Thai native beef cattle fed a rice straw-based diet.

Bioaccessibility and Microencapsulation of Lactobacillus sp. to Enhance Nham Protein Hydrolysates in Thai Fermented Sausage.

The development of functional food products is increasingly gaining lots of interest and popularity among stakeholders. The aim of this study was to evaluate the bioaccessibility of three Lactobacillus sp. starter cultures, including Lacticaseibacillus casei KKU-KK1, Lactiplantibacillus pentosus KKU-KK2, and Lactobacillus acidophilus KKU-KK3, in order to enhance the performance of the probiotic potential of Nham protein hydrolysates in Thai fermented sausage using microencapsulation technology. Probiotic microcapsules were created from a novel wall material made up of a combination of glutinous rice flour and inulin through a freeze-drying process. Accordingly, the results of three formulations of Nham probiotic and spontaneous fermentation (control) characterized by their physicochemical and microbiological characteristics displayed a correlation between an increase in the amount of total acidity, the population of lactic acid bacteria, and the generated TCA-soluble peptides, while the pH and total soluble protein gradually decreased under proteolysis during the fermentation time. The fractionation of Nham protein hydrolysates (NPHs) was prepared using a microwave extraction process: NPH-nham1, NPH-nham2, and NPH-nham3 (10 mg/mL with fermentation time 114 h), exhibited the highest DPPH radical-scavenging activity and FRAP-reducing power capacity as well, compared to NPH-nhamcontrol at p < 0.05. Moreover, those NPHs peptides showed dose-dependent inhibiting of selected pathogenic bacteria (E. coli TISTR 073, S. aureus TISTR 029, and Ent. aerogenes TISTR 1540). Anti-microbial properties of NPHs peptides against gram-negative bacteria were higher than against gram-positive bacteria. In conclusion, the bioaccessibility of NPHs peptides was significantly enhanced by micro-encapsulation and showed a potential bioactive characteristic for developing into a probiotic agent.

Mitragyna speciosa Korth Leaf Pellet Supplementation on Feed Intake, Nutrient Digestibility, Rumen Fermentation, Microbial Protein Synthesis and Protozoal Population in Thai Native Beef Cattle.

This experiment evaluated the use of Mitragyna speciosa Korth leaf pellets (MSLP) on feed intake and nutrient digestibility in Thai native beef cattle. Four Thai native beef cattle steers were randomly assigned according to a 4 × 4 Latin square design to receive four dietary treatments. The treatments were as follows: control (no supplementation), MSLP supplement at 10 g/hd/d, MSLP supplement at 20 g/hd/d and MSLP supplement at 30 g/hd/d, respectively. All animals were fed a concentrate mixture at 0.5% body weight, while urea lime-treated rice straws were fed ad libitum. Findings revealed that feed intakes were increased by MSLP, which also significantly increased the digestibility of dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF). Ruminal total volatile fatty acid (TVFA) concentration and propionate (C3) proportion were increased (p < 0.05) with MSLP supplementation, whereas ruminal ammonia-N (NH3-N), plasma urea nitrogen (PUN), acetate (C2), C2:C3 ratio and estimated methane (CH4) production decreased (p < 0.05). Total bacterial, Fibrobacter succinogenes and Ruminococus flavefaciens populations increased (p < 0.05) at high levels of MSLP supplementation, while protozoal populations and methanogenic archaea reduced (p < 0.05). Supplementation of MSLP also increased the efficiency of microbial nitrogen protein synthesis. Supplementing beef cattle with MSLP 10−30 g/hd/d significantly increased rumen fermentation end products and nutrient digestibility by mitigating protozoal populations and estimated CH4 production.

Influence of bamboo grass (Tiliacora triandra, Diels) pellet supplementation on in vitro fermentation and methane mitigation.

BACKGROUND: The aim of this research was to investigate the influence of bamboo grass (Tiliacora triandra, Diels) pellet (BP) containing phytonutrients on rumen fermentation under various level of roughage (R) to concentrate (C) ratios. The experimental treatments were randomly assigned following a completely randomized design using a 3 × 5 factorial arrangement. The first factor was ratios of R:C at 100:0, 70:30, and 30:70 and the second factor was BP supplementation levels at 0, 1, 2, 3, and 4% of dry matter substrate, respectively. RESULTS: The ratio of R:C significantly enhanced rumen gas production especially when increased level of concentrate. Moreover, dry matter degradability of fermentation were improved (P < 0.01) by R:C and level of BP supplementation, and there was an interactive effect. The ammonia nitrogen (NH3 -N) concentration, protozoal population and methane (CH4 ) production were remarkably influenced (P < 0.01). There were highly significant interactive effects between ratio of R:C and level of BP supplementation. Furthermore, fermentation parameters especially those of propionate (C3 ) concentration was profoundly increased by higher ratio of R:C and by the BP supplementation, interactive effect (P < 0.01). Notably, both level of R:C and BP supplementation significantly reduced NH3 -N concentration and CH4 production. Interactive effects of both factors were obtained (P < 0.01). CONCLUSION: The ratio of R:C at 30:70 with BP supplementation at 4% could enhance fermentation characteristics and reduce CH4 production, while the interactive effects were additionally observed. The BP could be a good phytonutrient source to modulate rumen fermentation. © 2022 Society of Chemical Industry.

Cricket Meal (Gryllus bimaculatus) as a Protein Supplement on In Vitro Fermentation Characteristics and Methane Mitigation.

The aim of this work was to conduct the effects of cricket (Gryllus bimaculatus) meal (CM) as a protein supplement on in vitro gas production, rumen fermentation, and methane (CH4) mitigation. Dietary treatments were randomly assigned using a completely randomized design (CRD) with a 2 × 5 factorial arrangement. The first factor was two ratios of roughage to concentrate (R:C at 60:40 and 40:60), and the second factor was the level of CM to replace soybean meal (SBM) in a concentrate ratio at 100:0, 75:25, 50:50, 25:75, and 0:100, respectively. It was found that in vitro DM degradability and the concentration of propionic (C3) were significantly increased (p < 0.05), while the potential extent of gas production (a + b), acetate (C2), acetate and propionate (C2:C3) ratio, and protozoal population were reduced (p < 0.05) by lowering the R:C ratio and the replacement of SBM by CM. In addition, rumen CH4 production was mitigated (p < 0.05) with increasing levels of CM for SBM. In this study, CM has the potential to improve rumen fermentation by enhancing C3 concentration and DM degradability, reduced methane production, and C2:C3 ratio. The effects were more pronounced (p < 0.05) at low levels of roughage.

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.

Supplementation of fruit peel pellet containing phytonutrients to manipulate rumen pH, fermentation efficiency, nutrient digestibility and microbial protein synthesis.

BACKGROUND: Phytonutrient pellet, a new rumen enhancer, was formulated from various tropical fruit peels containing phytonutrients (condensed tannins and saponins) and named MARABAC. To substantiate the MARABAC supplementation effect, it was supplemented with low and high levels of concentrate supplementation in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement using beef cattle. Based on this investigation, interesting findings were highlighted and are reported herein. RESULTS: The high level of concentrate supplementation (HCS) reduced rumen pH remarkably, but was buffered and enhanced by MARABAC supplementation. Rumen pH was reduced to 5.74 at 8 h, post feeding upon receiving HCS, and was buffered back to 6.19 with MARABAC supplementation. The supplementation exhibited an additional pronounced (P < 0.01) effect on improving nutrient digestibility and efficiency of microbial nitrogen supply, mitigating rumen methane production and reducing protozoal population. Rumen and fermentation end-products, especially propionate production, were enhanced (P < 0.05), while rumen methane production was subsequently mitigated (P < 0.01). CONCLUSION: MARABAC is a new promising dietary rumen enhancer for future replacement of chemicals and antibiotics used to enhance the rumen fermentation. Nevertheless, more in vivo feeding trials should be further conducted to elucidate the insight impacts. © 2021 Society of Chemical Industry.

Dragon fruit (Hylocereus undatus) peel pellet as a rumen enhancer in Holstein crossbred bulls.

OBJECTIVE: An experiment was conducted to assess the effect of dragon fruit peel pellet (DFPP) as a rumen enhancer of dry matter consumption, nutrient digestibilities, ruminal ecology, microbial protein synthesis and rumimal methane production in Holstein crossbred bulls. METHODS: Four animals, with an average live-weight of 200±20 kg were randomly assigned in a 4×4 Latin square design to investigate the influence of DFPP supplementation. There were four different dietary treatments: without DFPP, and with 200, 300, and 400 g/h/d, respectively. RESULTS: Results revealed that dry matter consumption of total intake, rice straw and concentrate were not significantly different among treatments (p>0.05). It was also found that ruminal pH was not different among treatments (p>0.05), whilst protozoal group was reduced when DFPP increased (p<0.01). Blood urea nitrogen and NH3-N concentrations were increased at 400 g of DFPP supplementation (p<0.01). Additionally, volatile fatty acid production of propionate was significantly enhanced by the DFPP supplementation (p<0.05), while production of methane was consequently decreased (p<0.05). Furthermore, microbial protein synthesis and urinary purine derivatives were remarkably increased especially at 400 g of DFPP supplementation (p<0.05). CONCLUSION: Plant secondary compounds or phytonutrients (PTN) containing saponins (SP) and condensed tannins (CT) have been reported to influence rumen fermentation. DFPP contains both CT and SP as a PTN. The addition of 400 g of DFPP resulted in improved rumen fermentation end-products especially propionate (C3) and microbial protein synthesis. Therefore, DFPP is a promising rumen enhancer and indicated a significant potential of DFPP as feedstuff for ruminant feed to mitigate rumen methane production.

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

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.

Mangosteen Peel Liquid-Protected Soybean Meal Can Shift Rumen Microbiome and Rumen Fermentation End-Products in Lactating Crossbred Holstein Friesian Cows.

Rumen bypass protein can enhance protein availability in the lower gut. This study investigated the use of liquid-containing phytonutrients in dairy cows as a dietary additives to reduce rumen protein degradation. Four crossbred lactating Holstein Friesian cows (75% Holstein Friesian with 25% Thai native breed) with an initial body weight (BW) of 410 ± 20 kg were randomly assigned to a 2 × 2 factorial arrangement [two crude protein (CP) levels with soybean meal (SBM) or mangosteen peel liquid-protected soybean meal (MPLP)-SBM] in a 4 × 4 Latin square design experiment. Dietary treatments were as follows: T1 = SBM in low crude protein concentrate (LPC) (SBM-LPC); T2 = MPLP-SBM in LPC (MPLP-SBM-LPC); T3 = SBM in high crude protein concentrate (HPC) (SBM-HPC); T4 = MPLP-SBM in HPC (MPLP-SBM-HPC). Apparent digestibilities of organic matter (OM) and neutral detergent fiber (aNDF) were increased (p < 0.05) by CP level in the HPC diet (19% CP), with higher OM and aNDF digestibilities. High crude protein concentrate increased (p < 0.05) the propionic acid in the rumen but reduced (p < 0.05) the acetic acid-to-propionic acid ratio and methane (CH4) production. Rumen microbial populations of the total bacteria, Fibrobacter succinogenes and Butyrivibrio fibrisolvens were increased (p < 0.05) by HPC. Real-time PCR revealed a 30.6% reduction of rumen methanogens by the MPLP-SBM in HPC. Furthermore, efficiency of microbial nitrogen synthesis (EMNS) was 15.8% increased (p < 0.05) by the MPLP-SBM in HPC when compared to SBM-LPC. Milk yield and milk composition protein content were enhanced (p < 0.05) by both the CP level in concentrate and by MPLP inclusion. In this experiment, a high level of CP and the MPLP-SBM enhanced the ruminal propionate, shifted rumen microbiome, and enhanced milk yield and compositions.

Potential use of Flemingia (Flemingia macrophylla) as a protein source fodder to improve nutrients digestibility, ruminal fermentation efficiency in beef cattle.

OBJECTIVE: This study aimed at studying the potential use of Flemingia (Flemingia macrophylla) as a protein source fodder to improve nutrients digestibility and ruminal fermentation efficiency in beef cattle. METHODS: Four, Thai native beef cattle were randomly assigned in a 4×4 Latin square design. Four levels of Flemingia hay meal (FHM) were used to replace soybean meal (SBM) in the concentrate mixtures in four dietary treatments replacing levels at 0%, 30%, 60%, and 100% of SBM. RESULTS: The experimental findings revealed that replacements did not effect on intake of rice straw, concentrate and total dry matter (DM) intake (p>0.05). However, the apparent digestibilities of DM, organic matter, crude protein, acid detergent fiber, and neutral detergent fiber were linearly increased up to 100% replacement levels. Moreover, the production of total volatile fatty acids, and propionate concentration were enhanced (p<0.05) whereas the concentration of acetate was reduced in all replacement groups. Consequently, the CH4 production was significantly lower when increasing levels of FHM for SBM (p<0.05). Furthermore, rumen bacterial population was additionally increased (p<0.05) while protozoal population was clearly decreased (p<0.05) in all replacement groups up to 100%. In addition, microbial nitrogen supply and efficiency of microbial nitrogen synthesis were enhanced (p<0.05), as affected by FHM replacements. CONCLUSION: The findings under this experiment suggest that 100% FHM replacement in concentrate mixture enhanced rumen fermentation efficiency, nutrients digestibilities, bacterial population, microbial protein synthesis, and subsequently reduced CH4 production in beef cattle fed on rice straw.

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

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.

Rapeseed pod meal can replace concentrate and enhance utilization of feed on in vitro gas production and fermentation characteristics.

Rapeseed provides multi-products as human food and animal feed especially the oil and meal. Rapeseed oil and meal after extraction are nutritious and have been used in animal feeding. This study aimed at studying the effect of rapeseed pod meal as the replacement of concentrate (RPM) on in vitro gas and fermentation characteristics. Dietary treatments were imposed in a 2 × 6 factorial arrangement according to a completely randomized design (CRD). The first factor was two ratios of roughage to concentrate (R:C at 60:40, and 40:60) and the second factor was six levels of RPM at 0, 20, 40, 60, 80, and 100% of dietary substrate. The results revealed that the R:C ratio and RPM increased kinetics of gas production, in vitro degradability and improved rumen fermentation (P < 0.001). Ratio of R:C influenced (P < 0.05) on both protozoal population and methane production, while level of RPR did not. Both factors had influenced (P < 0.01) a, a + b, and c, as well as total gas production; nevertheless, there were no interactions (P > 0.05). Interestingly, both factors have greatly impacted on TVFA, C3 (P < 0.01) and tended to reduce methane production as level of RPM replacement increased. In conclusion, RPM improved rumen fermentation and increased in vitro DM degradability, hence is potential for replacement of concentrate and effectively used for ruminant feeding.

Strategic supplementation of cassava top silage to enhance rumen fermentation and milk production in lactating dairy cows in the tropics.

High-quality protein roughage is an important feed for productive ruminants. This study examined the effects of strategic feeding of lactating cows with cassava (Manihot esculenta) top silage (CTS) on rumen fermentation, feed intake, milk yield, and quality. Four early lactating crossbred dairy cows (75% Holstein-Friesian and 25% Thai) with body weight (BW) 410 ± 30 kg and milk yield 12 ± 2 kg/day were randomly allotted in a 4 × 4 Latin square design to four different supplementation levels of CTS namely, 0, 0.75, 1.50, and 2.25 kg/day of dry matter (DM). Strategic supplementation of CTS significantly affected ruminal fermentation end-products, especially increased propionate production, decreased protozoal population and suppressed methane production (P < 0.05). Increasing the CTS supplementation level substantially enhanced milk yield and the 3.5% FCM from 12.7 to 14.0 kg/day and from 14.6 to 17.2 kg/day (P < 0.05) for non-supplemented group and for the 2.25 kg/day supplemented group, respectively. We conclude that high-quality protein roughage significantly enhances rumen fermentation end-products, milk yield, and quality in dairy cows.

Supplementation of Flemingia macrophylla and cassava foliage as a rumen enhancer on fermentation efficiency and estimated methane production in dairy steers.

Four rumen-fistulated dairy steers, 3 years old with 180 ± 15 kg body weight (BW), were randomly assigned according to a 4 × 4 Latin square design to investigate on the effect of Flemingia macrophylla hay meal (FMH) and cassava hay meal (CH) supplementation on rumen fermentation efficiency and estimated methane production. The treatments were as follows: T1 = non-supplement, T2 = CH supplementation at 150 g/head/day, T3 = FMH supplementation at 150 g/head/day, and T4 = CH + FMH supplementation at 75 and 75 g/head/day. All steers were fed rice straw ad libitum and concentrate was offered at 0.5 % of BW. Results revealed that supplementation of CH and/or FMH did not affect on feed intake (P > 0.05) while digestibility of crude protein and neutral detergent fiber were increased especially in steers receiving FMH and CH+FMH (P < 0.05). Ruminal pH, temperature, and blood urea nitrogen were similar among treatments while ammonia nitrogen was increased in all supplemented groups (P < 0.05). Furthermore, propionic acid (C3) was increased while acetic acid (C2), C2:C3 ratio, and estimated methane production were decreased by dietary treatments. Protozoa and fungi population were not affected by dietary supplement while viable bacteria count increased in steers receiving FMH. Supplementation of FMH and/or FMH+CH increased microbial crude protein and efficiency of microbial nitrogen supply. This study concluded FMH (150 g/head/day) and/or CH+FMH (75 and 75 g/head/day) supplementation could be used as a rumen enhancer for increasing nutrient digestibility, rumen fermentation efficiency, and microbial protein synthesis while decreasing estimated methane production without adverse effect on voluntary feed intake of dairy steers fed rice straw.