Effects of dietary crude glycerin supplementation on nutrient digestibility, ruminal fermentation, blood metabolites, and nitrogen balance of goats

The effect of excessive elemental sulfur addition on feed intake, digestibility, rumen characteristics, blood metabolites and nitrogen balance in Thai native beef cattle fed a diet containing high fresh cassava root

This study aimed to study the effect of excessive elemental sulfur addition on intake, digestibility, rumen characteristics, blood metabolites and nitrogen balance in Thai native beef cattle fed diets containing high fresh cassava root (FCR) supplementation. Four Thai native beef cattle with an initial body weight (BW) of 100 ± 10.0 kg were used and randomly assigned to a 2 × 2 factorial in a 4 × 4 Latin square design. Two levels of FCR supplementation at 15 (FCR-1.5) and 20 g/kg of BW (FCR-2) and two levels of sulfur supplementation in concentrate at 10 (Sulfur-1) and 20 g/kg dry matter concentrate (Sulfur-2) were evaluated. This study showed that sulfur and FCR in combination (p < 0.05) increased dry matter and organic matter digestibility and bacterial population. Sulfur-2 resulted in higher (p < 0.05) sulfur intake and serum thiocyanate concentration than Sulfur-1. FCR-2 had a greater (p < 0.05) FCR intake, total volatile fatty acids and propionate concentration than FCR-1.5. In conclusion, excessive elemental sulfur addition with high FCR supplementation showed no negative effect in Thai native beef cattle.

Effect of Feeding Discarded Durian Peel Ensiled with Lactobacillus casei TH14 and Additives in Total Mixed Rations on Digestibility, Ruminal Fermentation, Methane Mitigation, and Nitrogen Balance of Thai Native–Anglo-Nubian Goats

The objective of this study was to evaluate the effect of fermented discarded durian peel with Lactobacillus casei TH14, cellulase, and molasses separately or in combination in total mixed rations on feed utilization, digestibility, ruminal fermentation, and nitrogen utilization in growing crossbreed Thai Native–Anglo-Nubian goats. Five crossbreed Thai Native–Anglo-Nubian goats (50%) at 9 to 12 months of age and 20 ± 1 of body weight (BW) were assigned to a 5 × 5 Latin square design. Evaluated treatments were fermented discarded durian peel without additives (FDP), fermented discarded durian peel with 5% of molasses (FDPM), fermented discarded durian peel with 2% of cellulase (FDPC), fermented discarded durian peel with 1.0 × 105 cfu/g fresh matter of L. casei TH14 (FDPL), and fermented discarded durian peel with 5% of molasses and 1.0 × 105 cfu/g fresh matter of L. casei TH14 (FDPML). This study showed that acid detergent fiber intake was different (p < 0.05) between goats fed FDP and those fed FDPLM, 0.24 g/d and 0.20 g/d, respectively. The FDPML ration had significantly (p < 0.05) greater apparent nutrient digestibility and a better propionate concentration compared with other treatments. FDPML treatment significantly (p < 0.05) decreased the acetate-to-propionate ratio, methane production, and urinary nitrogen. Therefore, treated discarded durian peel with molasses and L. casei TH14 in combination could add 25% of dry matter into the diet for growing goats without a negative impact.

The effect of leucaena hay as a source of effective fibre and nutrients in diets with forage palm for finishing sheep in semi-arid regions

The present study was conducted to evaluate the intake, digestibility and nitrogen balance of diets for finishing sheep, containing leucaena hay as a source of effective fibre and forage palm. Twenty-one male sheep were used in a randomized block design with three treatments, represented by total diets, where the forage was leucaena hay and forage palm in natura in proportions 350:650, 450:550 and 550:450 g/kg respectively. For the pH and NH₃ -N in the ruminal fluid, and urea in the blood serum, plots split in time were adopted. Dry matter and nutrient digestibility, and the nitrogen balance were not influenced (p > .05) by the diets. The neutral detergent fibre digestibility decreased (p < .05) as the proportions of leucaena hay in the diets increased. The pH and NH₃ -N were suitable for ruminal fermentation, and blood urea was maintained under normal physiological conditions for sheep. Combining 350 to 550 g/kg of leucaena hay with 450 to 650 g/kg of forage palm in total diets with a forage:concentrate ratio of 60:40 in late-maturing sheep meets the nutritional requirements for daily gain 200 g, characterizing leucaena hay as important source of effective fibre and nutrients in diets.

Using glycerin with chitosan extracted from shrimp residue to enhance rumen fermentation and feed use in native Thai bulls

Background and Aim:

Crude glycerin is changed to propionate in the rumen, while chitosan can be used as a feed supplement to increase propionic acid concentration and decrease methane (CH₄) production. We hypothesized that supplementation with a combination of a high level of crude glycerin with chitosan could have a beneficial effect on ruminal fermentation and mitigate CH₄ production. This study aimed to explore the combined effects of crude glycerin and chitosan supplementation on nutrient digestibility, rumen fermentation, and CH₄ calculation in native Thai bulls.

Materials and Methods:

Four 2-year-old native Thai bulls, weighing 150±20 kg, were kept in a 2×2 factorial arrangement in a 4×4 Latin square design. Factor A represented the incorporation of crude glycerin at 10.5% and 21% of the dry matter (DM) of a total mixed ration (TMR), and factor B represented the supplementation of chitosan at 1% and 2% DM of a TMR.

Results:

Increasing levels of crude glycerin at 21% decreased DM intake by 0.62 kg/day compared with 10.5% crude glycerin (p<0.05), whereas nutrient digestibility did not change (p>0.05). The incorporated crude glycerin and supplemented chitosan levels did not affect the pH, temperature, concentrations of ammonia-nitrogen, microbial population, and blood urea nitrogen (p>0.05). Supplemented chitosan and incorporated crude glycerin did not show any interaction effects on the molar portions and total volatile fatty acids (VFAs), except estimated CH₄. Increasing the incorporated crude glycerin levels increased propionate and decreased the ratio of acetate to propionate ratio, whereas levels of butyrate, acetate, and total VFAs were unchanged. The combination of crude glycerin at 21% in the TMR with chitosan at 2% reduced CH₄ estimation by 5.08% compared with the other feed treatment.

Conclusion:

Increasing incorporated crude glycerin levels in a TMR significantly elevated the propionate concentration, whereas combining 21% crude glycerin in the TMR diet with 2% chitosan supplementation could depress CH₄ estimation more effectively than adding one of these supplements alone.

Meat goat diet supplementation with crude glycerine: Ruminal fermentation metabolism, blood chemistry profile, animal performance and carcass traits

The objective of this experiment was to determine the effects of feeding varying levels of crude glycerine (CG) on dry matter intake (DMI), animal performance, carcass traits and rumen volatile fatty acids (VFA) concentration in meat goats. Twenty-four intact male Boer goats (23.9 ± 1.0 kg initial BW and 4-5 months of age) were randomly assigned to one of four experimental diets (n = 6) containing 30% bermudagrass hay plus 70% concentrate mix with 0, 5, 10 or 15% CG in the diet on an as-fed basis, substituted for the corn portion of the concentrate. Feed offered and refusals were monitored daily for 84 days. Goats were weighed at 28-days interval. Blood and rumen samples were collected on day 84. At the end of the 84-days feeding period, goats were harvested, and carcass characteristics measured. Feed intake, average daily gain (ADG), gain-to-feed ratio (G:F), carcass traits and VFA concentrations were analysed as a completely randomized design. The CG did not influence animal body weight (BW) changes, ADG and G:F ratio but tended to (p = 0.06) decrease DMI. Molar per cent propionic acid increased linearly (p < 0.05) with increasing CG. The acetate: propionate (A:P) ratio decreased (p < 0.05) with increasing amounts of CG in the diet. The CG addition tended to increase (p = 0.09) the longissimus muscle (LM area) in meat goats. In conclusion, CG can replace corn in diet for growing meat goats when fed up to 15% of diet, improving ruminal propionate concentration, but decreasing A:P ratio without affecting animal performance and carcass traits.

Biofuel by-product can replace partially corn in supplement for Angus × Nellore heifers: productive performance and meat characteristics

The aim of this is study was to test the hypothesis that corn can be partially replaced by crude glycerin (at a level of 50%) without affecting performance, ingestive behavior, ruminal parameters, meat composition, and fatty acids profile on the meat of heifers. Sixty-four intact plus four rumen cannulated Angus × Nellore heifers (359.0 ± 12.15 kg BW) were used. The cannulated animals received the same diets as the intact ones to determine the ruminal N-NH3 concentration, pH, and chewing activity weekly. All heifers were maintained in Brachiaria brizantha pasture and supplemented with a concentrate containing corn, soybean meal, urea, premixed minerals, and glycerin partially replacing corn. A completely randomized experimental design was used, with two treatments (corn ground or glycerin + corn ground). The inclusion of crude glycerin (high fat) decreased nutrients intake and ruminal N-NH3 concentration in the rumen but increased lipid intake. Inclusion of glycerin had no effect (P > 0.05) on ruminal pH, daily gain, performance, time spent eating, rumination, idling, or water intake. The moisture, ash, and protein contents of meat were not affected (P > 0.05) by crude glycerin intake. Crude glycerin increased saturated fatty acids (C14:0, C16:0, and C18:0) and decreased unsaturated fatty acids (C18:2n6c and C20:1) in meat. Despite the reduction in nutrient intake, we recommend crude glycerin to replace corn in concentrate because glycerin did not impair the performance, meat composition, and ruminal pH. Therefore, crude glycerin is a by-product that can partially replace corn in diets efficiently.

Combining Crude Glycerin with Chitosan Can Manipulate In Vitro Ruminal Efficiency and Inhibit Methane Synthesis

It was hypothesized that the combination of glycerin and chitosan improves ruminal fermentation efficiency via an enhanced propionate (C3) and reduces in vitro CH₄ production. This was explored through in vitro gas production with substrates containing crude glycerin, which replaced cassava chips in the studied ration. The experimental design was organized following a 3 × 3 factorial in completely randomized design and the arrangement of treatments were different levels of crude glycerin supplementations 0, 10.5, and 21% of total mixed ration (TMR) and chitosan levels were added at 0, 1, and 2% dry matter (DM) of substrate. Then, 0.5 g of TMR substrates were added into 40 mL bottles, together with respective doses of chitosan and then incubated at 39 °C. The dietary treatments were performed in three replicates within the incubation, and incubations were repeated on three separate days (runs). No interactions were found between crude glycerin and chitosan doses in terms of theoretical maximum of asymptotic gas production (b), rate of gas production (c), the discrete lag time prior to gas production (L), or the cumulative gas production at 96 h of incubation (p > 0.05). Cumulative gas production at 96 h of incubation was similar among the doses of crude glycerin and levels of chitosan, which ranged from 64.27 to 69.66 mL/g DM basis of substrate (p > 0.05). The concentration of ruminal NH₃-N after 2 and 4 h of incubation ranged from 14.61 to 17.10 mg/dL and did not change with the addition of crude glycerin with chitosan (p > 0.05). The concentration of CH₄ after 2 h of incubation did not change among treatments (p > 0.05), whereas after 4 h of incubation, CH₄ synthesis was significantly reduced by enhancing doses of crude glycerin and chitosan (p < 0.05). The combination of 21% of crude glycerin in TMR with 2% chitosan depressed CH₄ production as much as 53.67% when compared to the non-supplemented group. No significant crude glycerin and chitosan interaction effect was detected for in vitro digestibility of nutrients after incubation for 12 and 24 h using the in vitro gas production technique (p > 0.05). In addition, no significant changes (p > 0.05) were observed in total volatile fatty acids, acetate (C2) or butyrate content among treatments and between the main effects of crude glycerin with chitosan. At 4 h of incubation, ruminal C3 content and the C2 to C3 ratio changed significantly when crude glycerin and chitosan was added (p < 0.05). The 21% crude glycerin incorporate into TMR, in combination with 2% additional chitosan, increased C3 content by 26.41%, whereas the ratio of C2 to C3 was reduced by 31% when compared to the control group. Propionate concentration increased by 11.75% when increasing levels of chitosan at 2% of substrate, whereas the C2 to C3 ratio decreased by 13.99% compared to the 0% chitosan group. The inclusion of crude glycerin at 21% in TMR diets with chitosan supplementation at 2% enhanced ruminal propionate concentration and reduced methane production without causing any detrimental effect on the gas kinetics or nutrient digestibility.

Elevated concentrations of crude glycerin in diets for beef cattle: feedlot performance, carcass traits, and ruminal metabolism1

Three experiments were conducted to evaluate the inclusion of crude glycerin (CG) in diets for beef cattle. In Exp. 1, 4 ruminally cannulated steers were fed diets with 0 or 15% CG (DM basis), to evaluate DM disappearance, VFA profiles, and gas production. There was a tendency for an interaction (P = 0.06) between diet fed to donor animals and substrate fed to in vitro system, and digestion was increased when CG was added to cultures with ruminal fluid from CG-fed animals. Total VFA were unaffected by diets or by substrate incubated. The CG increased production of propionate, butyrate, and valerate (P < 0.01) while the gas production was unaffected (P = 0.16). In Exp. 2, 24 crossbred heifers (334.4 ± 0.9 kg BW) were fed the same diets as Exp. 1, for 35 d. Fecal grab samples were collected 3 times daily on day 7, 21, and 35, to evaluate total tract digestibilities of DM, OM, and NDF. The CG improved digestibility of diet OM (P = 0.04), and DM followed a similar trend (P = 0.06), while the NDF digestibility was unaffected (P = 0.29). In Exp. 3, crossbred heifers (n = 374; 375.8 ± 36.1 kg BW) were used to evaluate feedlot performance and carcass traits when fed diets with 0, 7.5, or 15% CG, with or without added 0.3% salt. Heifers were assigned to 25 pens and were harvested on day 125. Removing salt from CG-based diets did not impact performance (P = 0.50). The CG did not influence average daily gain (P = 0.27), but decreased DM intake (P = 0.003), USDA Yield Grade (P = 0.01), and improved feed efficiency (P = 0.03), while tended to decrease USDA prime carcasses (P = 0.10). Carcass weight (P = 0.24), Longissimus muscle area (P = 0.63), and kidney, pelvic, heart fat (P = 0.59) were unaffected by CG. Twelfth-rib fat was less for heifers fed 15% CG without salt compared with the other treatments (P = 0.005), while marbling was less for heifers fed CG diets compared with the control-fed animals (linear, P = 0.004; quadratic, P = 0.02). In conclusion, GC can replace dry-rolled corn in diets for beef heifers when fed at 15% of diet DM, improving OM digestion, increasing ruminal propionate and butyrate without affecting greenhouse gas emissions. Feeding up to 15% CG improves feed efficiency but depresses marbling and tends to decrease Quality Grade. Removing supplemental salt from CG-diets has no impact on performance or carcass traits.

In vitro fermentation of Pennisetum clandestinum Hochst. Ex Chiov increased methane production with ruminal fluid adapted to crude glycerol

The aim of this trial was to determine the effect of ruminal fluid adapted to crude glycerol supplementation on in vitro methane and fermentation parameters of the forage Pennisetum clandestinum Hochst. Ex Chiov (Kikuyu forage) of 35 (D35) and 45 days (D45) of regrowth. Four non-lactating cannulated Holstein cows with 600 ± 33 kg LW, under a randomized Latin square design (4 animals × 4 periods), were used to obtain ruminal fluid after adaptation for 13 days within each period to supplementation in the rumen with crude glycerol (GL): 0 (GL0), 500 (GL1), 1000 (GL2), and 1500 g/cow/day (GL3). All the variables were analyzed under a 4 × 2 split-plot arrangement, where the ruminal fluid adaptation to supplementation with GL and its interaction with the incubated diets (GL× D) were analyzed. Ruminal pH values and in vitro apparent degradability of the dry matter (DMd) and organic matter (OMd) were not affected, with a decrease in the concentrations of NH₃-N and acetate by the ruminal fluid adapted to crude glycerol. The concentrations of propionate and butyrate increased, without affecting the total concentration of VFA in the ruminal fluid. The in vitro methane production increased with forage D35 and GL1, GL2, GL3. The in vitro methane production with the D45 forage increased with the ruminal fluid adapted to GL2 and GL3. The ruminal fluid adapted to crude glycerol supplementation increased in vitro methane production when incubating the forage Kikuyu.

Effects of crude glycerin from biodiesel on the diets of lambs: intake, digestibility, performance, feeding behavior, and serum metabolites

This study was conducted to test the hypothesis that the inclusion of crude glycerin of up to 21% of DM in the diets of lambs will not compromise variables related to animal production or health. Forty-four uncastrated Santa Inês crossbreed lambs with an average age of 5 mo and a BW average of 23.9 ± 0.34 kg (mean ± SD) were distributed into four treatment groups (11 replicates per group) including 0%, 7%, 14%, or 21% crude glycerin on a DM basis. The inclusion of crude glycerin in the diets promoted a quadratic increase in DM (P = 0.018), CP (P = 0.004), and TDN (P = 0.017). There was a linear decrease (P < 0.001) in NDF and nonfibrous carbohydrate (NFC) intake caused by glycerin in the diets. There was a linear increase (P < 0.001) in ether extract (EE) intake. There was a linear reduction in NDF (P = 0.011) and NFC (P < 0.001) for effective consumption of the diets. There was a linear increase (P < 0.001) in EE effectively consumed by the lambs, and there were no differences in the CP that was effectively consumed (P = 0.267) by glycerin. Digestibility coefficients of DM, CP, NDF, NFC, and TDN presented a linear decrease in crude glycerin inclusion. The EE digestibility presented a linear increase. The inclusion of crude glycerin in the diets promoted a quadratic increase in final BW (P = 0.015), ADG (P < 0.001), and G:F ratio (P < 0.001). There was no effect (P > 0.05) of crude glycerin inclusion in the diets on time spent (%); number of events per day; duration of events (minutes) for feeding, rumination, and idling; number of chews per bolus; or total chewing time for the lambs. The inclusion of crude glycerin in the diets improved feeding efficiency of DM (P = 0.005) and NDF (P = 0.004). The rumination efficiency of DM (P < 0.001) and NDF (P < 0.001) presented a linear decrease. The total protein, albumin, globulin, albumin:globulin ratio, triglycerides, alanine aminotransferase levels, aspartate aminotransferase, and gamma glutamyl transferase serum concentrations did not differ (P > 0.05) through the addition of crude glycerin to the diets of the lambs. However, the crude glycerin in the diets led to a linear decrease in urea-N (P = 0.004) and glucose (P <0.001), as well as a linear increase in the cholesterol (P = 0.043) serum concentrations of the lambs. The recommended inclusion of crude glycerin is up to a 4.7% DM level because of improved performance growth without compromising feeding behavior and blood metabolites.

Growth performance and digestion of growing lambs fed diets supplemented with glycerol

Two experiments were conducted to evaluate the effects of replacing corn with an increasing concentration of high-purity glycerol (>99%) on growth performance, economical efficiency, blood constituents and nutrient digestibility of growing lambs. In experiment one, 24 male lambs (initial BW=33.6±6.0 kg; age=6.75±0.75 months) were randomly assigned to one of the three experimental treatments containing 0%, 5% or 10% glycerol to replace corn in concentrate. In experiment two, nine lambs (initial BW=44.7±2.2 kg, age=8.84±0.32 months) were used in a digestion trial with three treatments (three lambs per treatment) with glycerol replacing corn at 0%, 5% or 10% in the concentrate. Total dry matter (DM) intake decreased quadratically (P=0.003) with increasing concentration of glycerol in the diet. Lambs fed glycerol diets had greater average daily gain (P=0.005) and better feed efficiency (P=0.002) compared with the control. Feed costs were also reduced with glycerol inclusion. Glycerol supplementation did not affect serum concentrations of total protein, albumin, globulin, total lipid, cholesterol and glucose concentrations. Glycerol supplementation had no effect (P>0.05) on organic matter and CP digestion, but improved DM (P=0.0003), crude fiber (P=0.10), ether extract (P=0.0002) and nitrogen-free extract (P=0.05) digestion. In conclusion, glycerol can replace corn up to 10% of DM in the diets of growing lambs.

Effect of supplementary glycerin on milk composition and heat stability in dairy goats

Objective

This experiment was studied the effects of various levels of crude glycerin (CG) in dairy goat diet on daily intake, milk yield, milk composition, some physical properties and some quality changes of goat milk after sterilization.

Methods

Twelve 75% Saanen dairy goats (body weight = 49±3 kg; days in milk = 60±12 d) were randomly assigned in a completely randomized design to evaluate the effects of three experimental diets consisting of 0%, 5%, and 10% CG (dry matter basis) which were formulated to meet or exceed the nutrient requirements of goats. Experimental dairy goats were evaluated for feed and milk yield. Milk samples were analyzed for their composition, including fatty acids, casein profile, fat globule size, and color, and were sterilized to evaluate milk heat stability.

Results

There were no significant differences between 0% and 5% CG treatments infeed. Increasing CG supplementation from 0% to 5% increased milk yield from 2.38±0.12 to 2.64±0.23 kg/goat/d. In addition, milk samples from 5% CG treatment had the highest total solids, fat content and lactose content, and largest fat globule size. Increasing CG to 10% resulted in a decrease in milk fat. After sterilizing at 116°C, F₀ = 3 min, goat milk samples from 5% CG treatment had slightly higher sediment content and comparatively higher degree of browning.

Conclusion

Considering milk yield, milk fat content and quality of sterilized milk, 5% CG supplementation in a total mixed ration has a potential for implementation in dairy goats.

Effects of crude glycerin from waste vegetable oil supplementation on feed intake, ruminal fermentation characteristics, and nitrogen utilization of goats

This experiment was evaluation of the effects of increasing concentrations of crude glycerin from waste vegetable oil (CGWVO) in diets on feed intake, digestibility, ruminal fermentation characteristics, and nitrogen balance of goats. Four crossbred male (Thai Native × Anglo Nubian) goats, with an average initial body weight (BW) of 31.5 ± 1.90 kg, were randomly assigned according to a 4 × 4 Latin square design. The dietary treatments contained 0, 2, 4, and 6 % of dietary dry matter (DM) of CGWVO. Based on this experiment, there were significantly different (P > 0.05) among treatment groups regarding DM intake and digestion coefficients of nutrients (DM, OM, CP, EE, NDF, and ADF), which goats receiving 6 % of CGWVO had lower daily DMI and nutrient intake than those fed on 0, 2, and 4 % of CGWVO. Ruminal pH, NH3-N, and blood urea nitrogen (BUN) concentration were unchanged by dietary treatments, except that for 6 % of CGWVO supplementation, NH3-N, and BUN were lower (P < 0.05) than for the diets 0 % of CGWVO, while the differences between the diets 0, 2, and 4 % of CGWVO were not significant. The amounts of N absorption and retention were similar among treatments, except that for 6 % of CGWVO which N absorption was lower (P < 0.05) than among treatments while the difference between the diets 0, 2, and 4 % of CGWVO were not significant. Based on this study, CGWVO levels up to 4 % in total mixed ration could be efficiently utilized for goats. This study was a good approach in exploiting the use of biodiesel production from waste vegetable oil for goat production.

Effects of Partial Replacement of Corn with Glycerin on Ruminal Fermentation in a Dual-Flow Continuous Culture System

The objective of this study was to evaluate the effects of partially replacing dry ground corn with glycerin on ruminal fermentation using a dual-flow continuous culture system. Six fermenters (1,223 ± 21 ml) were used in a replicated 3x3 Latin square arrangement with three periods of 10 d each, with 7 d for diet adaptation and 3 d for sample collections. All diets contained 75% concentrate and three dietary glycerin levels (0, 15, and 30% on dry matter basis), totaling six replicates per treatment. Fermenters were fed 72 g of dry matter/d equally divided in two meals/d, at 0800 and 2000 h. Solid and liquid dilution rates were adjusted daily to 5.5 and 11%/h, respectively. On d 8, 9, and 10, samples of 500 ml of solid and liquid digesta effluent were mixed, homogenized, and stored at -20°C. Subsamples of 10 ml were collected and preserved with 0.2 mL of a 50% H2SO4 solution for later determination of NH3-N and volatile fatty acids. Microbial biomass was isolated from fermenters for chemical analysis at the end of each experimental period. Data were analyzed using the MIXED procedure in SAS with α = 0.05. Glycerin levels did not affect apparent digestibility of DM (PLin. = 0.13; PQuad. = 0.40), OM (PLin. = 0.72; PQuad. = 0.15), NDF (PLin. = 0.38; PQuad. = 0.50) and ADF (PLin. = 0.91; PQuad. = 0.18). Also, glycerin inclusion did not affect true digestibility of DM (PLin. = 0.35; PQuad. = 0.48), and OM (PLin. = 0.08; PQuad. = 0.19). Concentrations of propionate (P < 0.01) and total volatile fatty acids (P < 0.01) increased linearly and concentrations of acetate (P < 0.01), butyrate (P = 0.01), iso-valerate (P < 0.01), and total branched-chain volatile fatty acids, as well as the acetate: propionate ratio (P < 0.01) decreased with glycerin inclusion. Linear increases on NH3-N concentration in digesta effluent (P < 0.01) and on NH3-N flow (P < 0.01) were observed due to glycerin inclusion in the diets. Crude protein digestibility (P = 0.04) and microbial N flow (P = 0.04) were greater in the control treatment compared with the other treatments and responded quadratically with glycerin inclusion. Furthermore, the inclusion of glycerin linearly decreased (P = 0.02) non-ammonia N flow. Glycerin levels did not affect the flows of total N (PLin. = 0.79; PQuad. = 0.35), and dietary N (PLin. = 0.99; PQuad. = 0.07), as well as microbial efficiency (PLin. = 0.09; PQuad. = 0.07). These results suggest that partially replacing dry ground corn with glycerin may change ruminal fermentation, by increasing total volatile fatty acids, and propionate concentration without affecting microbial efficiency, which may improve glucogenic potential of beef cattle diets.