scholarly journals 409 Effects of essential oils on in vitro ruminal fermentation using a high-concentrate substrate

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 165-165
Author(s):  
Nadira J Espinoza-Rock ◽  
Andrea O Doblado ◽  
Sebastian E Mejia-Turcios ◽  
Evandro Dias ◽  
Michael Sandes ◽  
...  
Keyword(s):  
Essential Oils ◽  
Fixed Effects ◽  
Block Design ◽  
Random Effect ◽  
Gas Production ◽  
Experimental Unit ◽  
Ruminal Fermentation ◽  
Cinnamic Aldehyde ◽  
Garlic Oil

Abstract A randomized complete block design was used to determine the effects of 4 concentrations of 4 essential oils (EO) on in vitro ruminal fermentation variables. In vitro fermentation consisted of 0.7 g of high concentrate substrate (86.7% DM) and 50 mL of 2:1 buffer:ruminal fluid inoculum incubated for 24 h for each batch (n = 3; separate days) Treatments were arranged as a 4 × 5 factorial. Factors included 4 EO (eugenol, cinnamic aldehyde, anethole, and garlic oil) at 5 concentrations (0, 10, 75, 200, and 400 mg/L of inoculum). Data were analyzed using the MIXED procedure of SAS with the fixed effects of EO, concentration, and their interaction, and random effect of day (block). Batch was considered the experimental unit. There was an interaction (P < 0.001) for total gas production, where a cubic effect (P ≤ 0.041) was observed for eugenol, cinnamic aldehyde, and anethole, and a quadratic effect (P = 0.001) was observed for garlic oil. No interactions (P > 0.05) were observed for in vitro OM digestibility (IVOMD) or CH4 production. There was an effect of EO (P < 0.001) on IVOMD, where eugenol reduced (P ≤ 0.007) digestibility compared with anethole and garlic oil, which promoted the greatest (P ≤ 0.029) IVOMD. Methane production (mmol/g OM fermented) was affected by EO (P < 0.001), where it was decreased (P ≤ 0.001) by garlic oil compared with all other EO. There was an interaction (P < 0.001) for H2S production (µmol/g OM fermented), where it was linearly decreased (P = 0.003) and linearly increased (P < 0.001) as concentrations of eugenol and garlic oil increased, respectively. These EO had contradictory impacts on in vitro ruminal fermentation, thus combining them could potentially improve multiple aspects of in vitro and in vivo fermentation.

312 Effects of Bismuth Subsalicylate and Different Sulfate Concentrations on in vitro Ruminal Fermentation Using a Warm-season Perennial Hay Substrate

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 166-166
Author(s):  
Kenneth S Madrid ◽  
Andrea M Osorio ◽  
Francine M Ciriaco ◽  
Kymberly D Coello ◽  
Angel A Raudales ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Block Design ◽  
Random Effect ◽  
Gas Production ◽  
Experimental Unit ◽  
Ruminal Fermentation ◽  
In Vitro Fermentation ◽  
Bismuth Subsalicylate ◽  
H2s Production

Abstract A randomized complete block design was used to evaluate the effects of bismuth subsalicylate (BSS) on in vitro ruminal fermentation with differing concentrations of sulfate. In vitro fermentation consisted of 50 mL of a 4:1 buffer:ruminal fluid inoculum and 0.7 g (pre-dehydrated) of substrate [WW-B Dahl bluestem hay (Bothriochloa bladhii)] incubated for 48 h (39oC). Treatments were arranged as a 3 × 4 factorial with concentration of sulfate (0.2, 2.9, or 5.6 g sulfate/L buffer) and BSS (0.0, 0.165, 0.330, or 0.495% substrate DM) as the main factors. In vitro organic matter digestibility (IVOMD), and CH4, H2S, and total gas production (TGP) were measured. Data were analyzed using the MIXED procedure of SAS with the fixed effects of BSS, sulfate, and their interaction. Incubation day (block) was considered a random effect. The average of 2 bottles within day was considered experimental unit. A BSS × sulfate interaction was observed for TGP (P = 0.040) and H2S production (P < 0.001), where BSS had a larger negative impact on TGP and production of H2S with greater concentrations of sulfate. A linear effect (P < 0.001) of sulfate was observed for CH4 production per gram of incubated OM, where CH4 was decreased as sulfate concentration increased. A quadratic effect of sulfate was observed for IVOMD (P = 0.010) and pH (P = 0.009). Production of H2S linearly decreased (P = 0.001) as BSS concentration increased. The addition of BSS to in vitro incubations did not affect (P > 0.10) any other variables measured. Bismuth subsalicylate does not appear to have negative effects on in vitro fermentation parameters while decreasing H2S production; however, elevated concentrations of sulfate in the buffer appears to have negative impacts on fermentation. Further in vivo research is warranted to support BSS supplementation to cattle with high dietary sulfate.

scholarly journals 407 Effects of calcium-ammonium nitrate on in vitro ruminal fermentation using a wheat forage based substrate

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 165-166
Author(s):  
Andrea O Doblado ◽  
Sebastian E Mejia-Turcios ◽  
Nadira J Espinoza-Rock ◽  
Evandro Dias ◽  
Michael Sandes ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Methane Production ◽  
Block Design ◽  
Random Effect ◽  
Gas Production ◽  
Experimental Unit ◽  
Ruminal Fermentation ◽  
Calcium Ammonium Nitrate ◽  
N Concentration

Abstract A randomized complete block design was used to evaluate in vitro ruminal total gas and methane production, N-NH3 concentration, and digestibility of wheat forage when incubated with calcium-ammonium nitrate (CAN). The in vitro fermentation consisted of 50 mL of a 4:1 buffer:ruminal fluid inoculum and 0.7 g of substrate [DM; wheat (Triticum aestivum; 100%) or wheat:corn (88:12)] incubated for 48 h. Batches were incubated on 4 separate days. Treatments included: 1) wheat (W); 2) wheat + corn (WC); 3) WC + 2% CAN in the substrate DM (WCN); and 4) WC + 0.67% UREA in the substrate DM (WCU). Treatments WCN and WCU were isonitrogenous. In vitro organic matter digestibility (IVOMD) was determined after incubation for 48 h with inoculum, followed by a 48 h incubation with HCl and pepsin solutions. Data were analyzed using the MIXED procedure of SAS with the fixed effect of treatment and random effect of day (block). Batch was considered the experimental unit. Total gas production was reduced by WCN compared with WCU (P = 0.049) and WC (P = 0.001). The addition of corn without NPN increased (P = 0.004) total gas production compared to wheat. An increased (P = 0.009) IVOMD was observed for WC compared to W, while no differences (P = 0.416) were observed between WCN and WCU. Ammonia-N concentration was not different (P = 0.463) between WCN and WCU; and the inclusion of NPN increased (P ≤ 0.026) NH3-N concentration compared to W. Methane production (mmol/g OM fermented) was lesser (P < 0.001) for WCN compared to WCU. Total VFA concentration and acetate:propionate were not affected by treatment (P > 0.05). Therefore, CAN can potentially be used as a NPN source with the additional benefit of in vitro methane mitigation without negatively affecting IVOMD or total VFA concentration.

scholarly journals PSXII-41 Evaluation of grain sorghum hybrids reveals potential for improving ruminal fermentation

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 431-431
Author(s):  
James R Johnson
Keyword(s):  
Fixed Effects ◽  
Dry Matter ◽  
Culture Media ◽  
Random Effect ◽  
Gas Production ◽  
Block Designs ◽  
Ruminal Fermentation ◽  
Clemson University ◽  
Bicarbonate Buffer

Abstract In vitro incubations were used to compare fermentation characteristics of corn (uncharacterized hybrid) to 25 sorghum parental lines and hybrids (Clemson University; Richardson Seed Inc., Lubbock, TX; Scott Seed Company, Hereford, TX). Two experiments were conducted as randomized complete block designs using ruminal contents from two ruminally-fistulated steers (blocks). Grains were ground by a 1-mm screen and used as substrates (2 g, dry matter basis) in laboratory fermenters containing strained ruminal contents and bicarbonate buffer. Fermenters were equipped with pressure monitoring devices (ANKOM Technology, Macedon, NY) to quantify gas production as an indicator of microbial digestion. Cultures were incubated for 24 (experiment 1) to 30 hours (experiment 2), and gas production was recorded at 15-minute intervals. Dry matter disappearance was determined, and organic acid concentrations in the spent culture media were analyzed by gas chromatography. Experiment 1 compared corn to 24 sorghum cultivars, and experiment 2 compared corn to six sorghum cultivars, five of which were represented in experiment 1, plus one waxy hybrid. Data were analyzed using mixed models with cultivar as a fixed effect and block as a random effect. For gas production data, time and the interaction between time and cultivar also were used as fixed effects. For both experiments, there was an interaction between cultivar and time (P < 0.0001) for gas production, revealing large differences among cultivars with respect to their relative susceptibility to microbial fermentation. Similarly, dry matter disappearance; production of acetate, propionate, and butyrate; and acetate:propionate varied substantially among cultivars (P < 0.01), and in many cases exceeding measurements obtained with control corn. Sorghum cultivars used in these experiments varied widely in their susceptibility to digestion by ruminal microorganisms, revealing potential for development of hybrids that can compete with corn as energy sources while contributing to improved sustainability of feedlot production.

Effects of Calcium-ammonium Nitrate on in Vitro Ruminal Fermentation Using a Mature Mixed Winter Forage-based Substrate

2021 ◽  
Vol 99 (Supplement_2) ◽  
pp. 27-28
Author(s):  
Andrea M Osorio ◽  
Kenneth Madrid ◽  
Sergio Buitrago ◽  
Nicolas DiLorenzo ◽  
Francine M Ciriaco ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Treatment Effect ◽  
Methane Production ◽  
Block Design ◽  
Random Effect ◽  
Gas Production ◽  
Ruminal Fermentation ◽  
Calcium Ammonium Nitrate ◽  
Molar Proportion

Abstract A randomized complete block design was used to evaluate in vitro total gas production (TGP), methane production, concentration of NH3-N, and digestibility of mixed winter forage (CP 10.2% and NDF 58.6%) incubated with calcium-ammonium nitrate (CAN). In vitro fermentation consisted of 50 mL of a 4:1 buffer:ruminal fluid inoculum and 0.7 g of substrate [DM; wheat, triticale, and rye (Triticum aestivum, Triticosecale rimpaui, and Secale cereal; FOR) or forage:corn (90:10; CORN)] incubated for 48 h. Treatments included: 1) FOR; 2) CORN; 3) CORN + 2% CAN (DM; NIT); and 4) CORN + 0.67% UREA (DM; UREA). Treatments NIT and UREA were isonitrogenous. In vitro organic matter digestibility (IVOMD) was determined after incubation for 48 h, followed by a 48-h incubation with HCl and pepsin solutions. Data were analyzed using the MIXED procedure of SAS with the fixed effect of treatment and random effect of day (block). There was a treatment effect (P = 0.024) on TGP where NIT decreased TGP compared with CORN (P = 0.023), and NIT was not different from UREA. A greater IVOMD (P = 0.017) was observed for CORN compared with FOR. No differences were observed in IVOMD between UREA and NIT. There were no differences (P = 0.727) among all treatments for concentration of NH3-N. Total methane production was lesser for NIT (P ≤ 0.018) compared with all other treatments. There was a treatment effect for molar proportion of acetate (P = 0.039) and acetate:propionate (P = 0.034) where NIT tended (P = 0.058) to have a greater molar proportion of acetate compared to UREA. Total VFA concentration was not affected by treatment (P = 0.454). Calcium-ammonium nitrate influenced in vitro ruminal fermentation of a mature mixed winter forage, decreasing methane production without negatively affecting IVOMD or concentration of VFA.

scholarly journals 251 Evaluation of Condensed Algal Residue Solubles as an Ingredient in Cattle Finishing Diets

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 137-138
Author(s):  
Calvin Gibbons ◽  
Andrea K Watson ◽  
Galen E Erickson ◽  
Bradley M Boyd ◽  
Levi J McPhillips ◽  
...  
Keyword(s):  
Great Plains ◽  
Fixed Effects ◽  
Block Design ◽  
Random Effect ◽  
Distillers Grains ◽  
Experimental Unit ◽  
Omega 3 ◽  
Finishing Diets ◽  
Randomized Block Design ◽  
Algae Oil

Abstract Algae oil production for Omega-3 fatty acid supplementation yields a byproduct called Condensed Algal Residue Solubles (CARS; 25.4% DM, 19.3% CP, 8.3% Fat, 9.96% Na on DM basis), de-oiled algae cells with residual fermentation substrates. This study evaluated the use of CARS in feedlot finishing diets. Crossbreed steers, (n=480) were blocked and stratified by initial body weight (BW) into 4 blocks, and assigned randomly to treatments. Treatments were designed as a 2 x 3 factorial with 3 inclusions of CARS (0, 2.5, 5% of diet DM) and 2 different base diets representing Northern and Southern Great Plains diets. The Southern diets contained steam flaked corn and dry distillers grains while the Northern diets had dry rolled and high moisture corn with wet distillers grains. CARS replaced corn in both diets. All blocks were harvested after 148 days on feed. Performance data were analyzed as a randomized block design with CARS inclusion, base diet, and interactions as fixed effects, BW block as a random effect and pen (n=48) as the experimental unit. Orthogonal contrasts were used to test linear and quadratic effects of CARS inclusion. There were no significant interactions between CARS inclusion and diet type (P ≥ 0.49). Main effects of CARS indicated positive quadratic responses for carcass adjusted ADG, G:F, 12th rib back fat, yield grade (P < 0.01; increasing to 2.5% inclusion, decreasing at 5%) and hot carcass weight was both linear and quadratic (P ≤ 0.01 and P ≥ 0.06 respectively; 969, 977, 935 as CARS increased). Linear decrease in DMI, final adjusted BW and ribeye area (P ≤ 0.01) as CARS increased. Cattle fed the Southern diets had greater ADG and G:F compared to Northern diets (P < 0.01). Including 2.5% CARS in the diet improved feed efficiency in both Northern and Southern based feedlot diets.

305 Methane Emissions and Apparent Total Tract Nutrient Digestibility of Feedlot Beef Steers Under Intensive Management with or Without an Added Nutritional Packet

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 166-167
Author(s):  
Andrea M Osorio ◽  
Kaue T Tonelli Nardi ◽  
Igor Gomes Fávero ◽  
Kaliu G Scaranto Silva ◽  
Kymberly D Coello ◽  
...  
Keyword(s):  
Treatment Period ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Block Design ◽  
Random Effect ◽  
Methane Emissions ◽  
Nutrient Digestibility ◽  
Experimental Unit ◽  
Beef Steers ◽  
Ch4 Production

Abstract The effects of a nutritional packet were evaluated on CH4 emissions and apparent total tract nutrient digestibility of feedlot beef steers. Thirty Angus-crossbred steers (BW = 542 ± 8.4 kg) were used in a randomized complete block design and allocated into pens equipped with SmartFeed (C-Lock; 15 steers/treatment). Steers were consuming a steam-flaked corn-based diet (88% concentrate DM basis) ad libitum for the last 65 d on feed, and received the following treatments: 1) control and 2) a nutritional packet [0.29% DM basis; live yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g); Vitamin C (5.4 g/kg); Vitamin B1 (13.33 g/kg); NaCl (80 g/kg); KCl (80 g/kg)]. Methane emissions and apparent total tract nutrient digestibility were measured during 3 periods with 5-d of collections each. Gas emissions from steers were measured utilizing the SF6 tracer technique. Feed and fecal samples were collected once and twice (0700 h and 1600 h) daily, respectively, to determine digestibility of nutrients using iNDF as an internal marker. Steer was considered the experimental unit. Data were analyzed as repeated measures using the MIXED procedure of SAS with the fixed effects of treatment, period, and their interaction, and the random effect of block. No treatment × period interactions (P ≥ 0.125) were observed for DMI and any of the CH4 production variables (g/day, g/kg BW0.75, g/nutrient intake, and g/nutrient digested). Moreover, treatments did not affect digestibility of DM, OM, or ADF (P ≥ 0.300); however, digestibility of NDF was increased for treated cattle (P = 0.013), which resulted in a tendency (P = 0.098) to decrease CH4 production in g per kg NDF intake and decreased (P = 0.020) grams CH4 per kg NDF digested. The nutritional packet may be altering ruminal fermentation on intensively managed steers and improving fiber digestibility, which can have benefits on CH4 emission intensity.

PSXIII-8 Effects of different sources of Zn on in vitro ruminal fermentation and digestibility of a lactation diet

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 466-466
Author(s):  
Angela R Boyer ◽  
Yun Jiang ◽  
Alon Blakeney ◽  
Dennis Nuzback ◽  
Brooke Humphrey ◽  
...  
Keyword(s):  
Rumen Fluid ◽  
Random Effect ◽  
Rumen Fermentation ◽  
Gas Production ◽  
Ruminal Fermentation ◽  
Negative Effects ◽  
Minimum Concentration ◽  
High Metal Content ◽  
Different Sources

Abstract Vistore® minerals are hydroxychloride minerals that feature high metal content and improved bioavailability. This study was conducted to compare different sources of zinc (Zn) on in vitro rumen fermentation parameters. Three ruminally-cannulated Jersey heifers were adapted to a lactation diet for two weeks before used as donors. Three sources of Zn were tested at 20 ppm: No supplemental Zn (CON), ZnSO4, Vistore Zn, and another Zn hydroxychloride (Vistore-competitor). The concentration of Zn in this study was selected from a titration study (0 to 40 ppm ZnSO4) to identify the minimum concentration of ZnSo4 affecting rumen fermentation. The lactation diet (TMR) was dried and ground to 1mm and used as substrate. Rumen fluid was collected two hours after feeding. Substrate (0.5 g) was inoculated with 100 mL of 3:1 McDougall’s buffer: ruminal flued mixture at 39ºC for 24 h. Each treatment was run in triplicate and in three runs. Data were analyzed with R 3.0. The model included fixed effect of treatment and random effect of run. ZnSO4 reduced (P < 0.05) maximum gas production, DMD (54 vs. 55.9%) and cellulose (27.5 and 40.7%) digestibility. acetate to propionate ration (2.20 vs. 2.24) and NH3-N concentration (6.0 vs. 7.0 mg/dL), increased (P < 0.05) propionate % (27.2 vs 26.7%) compared to control. Vistore had higher pH than control (6.44 vs. 6.40, P = 0.02) but did not affect other parameters compared to CON. Vistore-competitor reduced total VFA production compared to control, ZnSO4, and Vistore (94 vs. 102, 106 and 107 mM, respectively, P = 0.01) but did not affect other parameters. In general, Vistore Zn maintained in vitro ruminal fermentation and digestibility, while ZnSO4 had negative effects on both fermentation and digestibility and Vistore-competitor reduced total VFAs. Results indicate hydroxychloride minerals may stabilize rumen parameters versus sulfate sources but different hydroxychloride sources appear to influence rumen parameters differently.

scholarly journals PSI-1 Effects of source and level of inclusion of engineered biocarbon in a total mixed beef cattle diet on in vitro methane emissions and fermentation parameters

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 290-291
Author(s):  
Paul Tamayao ◽  
Kim Ominski ◽  
Gabriel Ribeiro ◽  
Emma McGeough
Keyword(s):  
Fixed Effects ◽  
Pore Space ◽  
Block Design ◽  
In Vitro Study ◽  
Methane Emissions ◽  
Gas Production ◽  
Feed Digestibility ◽  
Fermentation Parameters ◽  
Barley Silage

Abstract This in vitro study evaluated seven different engineered biocarbon products supplied at three levels (0.5, 1.5 and 2.5 mg/ml inoculum) to determine their effects on total gas, methane production, and fermentation parameters when added to a barley silage-based diet. The biocarbon sources were derived from either coconut (CP001 and CP014) or pine (CP002, CP015, CP016, CP023, CP024) and differed in their physical properties and chemical composition. The coconut biocarbon sources were lower in pore space, particle size distribution and surface area but higher in bulk density than the pine products. The control consisted of only the barley-silage diet. The in vitro batch culture jars were incubated for 24 h at 39°C at the above inclusion levels in 0.5 g of diet. Gas samples were collected at 3, 6, 9, 12, 18 and 24 h and DM disappearance, pH, VFA and ammonia concentrations post incubation were measured. Data were analysed using the PROC MIXED in SAS as a randomized complete block design with treatment and rate as fixed effects and run and replicate as random effects. Total gas production was not affected by source of biocarbon (P = 0.85) and inclusion rate (P = 0.91). Cumulative methane (ml/g DM) had no response to biocarbon addition (P = 0.40) at any inclusion level (P = 0.48). Additionally, concentration of total VFA was not affected by treatment (P = 0.31) or inclusion rates (P = 0.25). NH3-N concentrations responded quadratically (P < 0.001) to all types of biocarbon. Higher inclusion rates of biocarbon linearly (P < 0.002) decreased feed digestibility, particularly the coconut-based biocarbon sources CP001 and CP014. In conclusion, supplementation of biocarbon to a TMR diet did not reduce methane emissions, but at higher levels of inclusion diet digestibility was negatively affected.

scholarly journals In vitro Effect of Essential Oils on Rumen Fermentation and Microbial Nitrogen Yield of High Concentrate Dairy Cow Diet

2016 ◽  
Vol 16 (2) ◽  
pp. 333-341
Author(s):  
Seyed Masoud Davoodi ◽  
Mohsen Danesh Mesgaran ◽  
Ali Reza Vakili ◽  
Reza Valizadeh ◽  
Abdollah Ghasemi Pirbalouti
Keyword(s):  
Essential Oils ◽  
Dairy Cow ◽  
Dry Matter ◽  
Basal Diet ◽  
Gas Production ◽  
Ruminal Fermentation ◽  
Plant Essential Oils ◽  
Microbial Nitrogen ◽  
Vitro Effect

Present study was conducted to investigate the effect of including plant essential oils on in vitro ruminal fermentation and microbial nitrogen synthesis of a dairy cow diet rich in concentrate. The treatments consisted of the diet alone (control; BD) as well as containing 50 and 100 μl L-1 essential oil of thyme (BDT), mint (BDM), savory (BDS), or a mixture of the essential oils at the rate of 1:1:1 (BDmix). Essential oils decreased gas production at 24, 48 and 96 h of incubation compared with that of BD. However, mint at the rate of 50 or 100 μl L-1 resulted an increase in the microbial nitrogen when compared to BD, BDS and BDT. The nitrogen content of truly undegraded residu (NDFN) content and NH3-N concentration were lower, while the dry matter digestibility was greater in the BDmix, regardless of dosage levels, as compared with the control. The inclusion of a mixture of essential oils at 50 μl L-1 to the basal diet caused intensified dry matter disappearance, in comparison to other treatments. Results showed that the synergetic effects of essential oils together in a dairy cow diet of rich in concentrate can alter rumen microbial fermentation and improve microbial protein yield.

scholarly journals Evaluation of different inclusion levels of dry live yeast impacts on various rumen parameters and in situ digestibilities of dry matter and neutral detergent fiber in growing and finishing beef cattle

2019 ◽  
Vol 97 (12) ◽  
pp. 4987-4998 ◽  
Author(s):  
Caitlyn M Cagle ◽  
Luiz Fernando D Batista ◽  
Robin C Anderson ◽  
Mozart A Fonseca ◽  
Matt D Cravey ◽  
...  
Keyword(s):  
Block Design ◽  
Random Effect ◽  
Gas Production ◽  
Neutral Detergent Fiber ◽  
Repeated Measure ◽  
Beneficial Result ◽  
Ch4 Concentration ◽  
Live Yeast

Abstract This study evaluated the effects of supplementing dry live yeast (LY; Saccharomyces cerevisiae) on in vitro gas production (IVGP) fermentation dynamics, pH, and CH4 concentration at 48 h, and in situ rumen parameters and digestibility of DM (DMD) and NDF (NDFD) of growing cattle during 3 feeding phases: grower (GRW) for 17 d (38% steamed-flaked corn; SFC), transition (TRANS) for 15 d (55.5% SFC: 1.2 Mcal/kg NEg), and finisher (FIN) for 13 d (73% SFC: 1.23 Mcal/kg NEg). Twenty British-crossbred, ruminally cannulated steers (183 kg ± 44 kg) 6 mo of age were blocked by weight into 5 pens containing Calan gate feeders and received a control (CON) diet (17.2% CP, 35.8% NDF, 86.7% DM) without LY on days −12 to 0. After that, animals were randomly assigned to treatments (TRT), 5 animals per TRT: CON or LY at inclusion rates of 5 g/d (LY1), 10 g/d (LY2), or 15 g/d (LY3) top dressed every morning at 0800 for 45 d. The DMD and NDFD were assessed during 7 separate collection days using in situ nylon bags containing 5 g of GRW, TRANS, or FIN diets, incubated at 1200 for 48 h. Protozoa counts (PC) were determined during 5 collection periods. Data were analyzed as a repeated measure within a randomized complete block design, assuming a random effect of the pen. For GRW, TRT altered the total gas production of the nonfiber carbohydrate (NFC; P = 0.045) and the fractional rate of degradation (kd) of the fiber carbohydrate (FC) pool (P = 0.001) in a cubic pattern (P ≤ 0.05): LY2 had the most gas production and fastest kd. TRT also influenced DMD (P = 0.035) and NDFD (P = 0.012) with LY2 providing the greatest digestibility. For TRANS, TRT tended to affect the NFC kd (P = 0.078) and influenced pH (P = 0.04) and DMD (P < 0.001) in which LY2 yielded the fastest kd, highest pH, and greatest DMD. For FIN, there was an effect of TRT on total gas production (P < 0.001) and kd (P = 0.004) of the NFC pool, FC kd (P = 0.012), in vitro CH4 concentration (P < 0.001), PC (P < 0.001), DMD (P = 0.039), and NDFD (P = 0.008). LY1 had the highest PC and provided the greatest DMD and NDFD. LY2 had the fastest kd of both the NFC and FC pools and had the least CH4 concentration. LY3 had the greatest NFC gas production. No specific dose–response pattern was observed, but 10 g/d provided the most beneficial result for all diets. We concluded that supplementation with LY affected IVGP as well as ruminal parameters and digestibilities.

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