Assessment of molasses products containing additives to reduce methane emissions from beef cattle

Simple SummaryNumerous enteric methane (CH4) mitigation opportunities exist to reduce enteric CH4 and other greenhouse gas emissions per unit of product from ruminants. Research over the past century in genetics, animal health, microbiology, nutrition, and physiology has led to improvements in dairy and beef cattle production. The objectives of this review are to evaluate options that have been demonstrated to mitigate enteric CH4 emissions per unit of products (energy-corrected milk, milk yield, average daily gain, dry matter intake, and gross energy intake) from dairy and beef cattle on a quantitative basis and in a sustained manner, and to integrate approaches in feeding, rumen fermentation profiles, and rumen microbiota changes to emphasize the understanding of these relationships between enteric CH4 emissions and animal productivities.Enteric methane (CH4) emissions produced by microbial fermentation in the rumen resulting in the emission of greenhouse gases (GHG) into the atmosphere. The GHG emissions reduction from the livestock industry can be attained by increasing production efficiency and improving feed efficiency, by lowering the emission intensity of production, or by combining the two. In this work, information was compiled from peer-reviewed studies to analyze CH4 emissions calculated per unit of milk production, energy-corrected milk (ECM), average daily gain (ADG), dry matter intake (DMI), and gross energy intake (GEI), and related emissions to rumen fermentation profiles (volatile fatty acids [VFA], hydrogen [H2]) and microflora activities in the rumen of beef and dairy cattle. For dairy cattle, there was a positive correlation (p < 0.001) between CH4 emissions and DMI (R2 = 0.44), milk production (R2 = 0.37; p < 0.001), ECM (R2 = 0.46), GEI (R2 = 0.50), and acetate/propionate (A/P) ratio (R2 = 0.45). For beef cattle, CH4 emissions were positively correlated (p < 0.05–0.001) with DMI (R2 = 0.37) and GEI (R2 = 0.74). Additionally, the ADG (R2 = 0.19; p < 0.01) and A/P ratio (R2 = 0.15; p < 0.05) were significantly associated with CH4 emission in beef steers. This information may lead to cost-effective methods to reduce enteric CH4 production from cattle. We conclude that enteric CH4 emissions per unit of ECM, GEI, and ADG, as well as rumen fermentation profiles, show great potential for estimating enteric CH4 emissions.

The mitochondrion, an organelle inherited exclusively from the mother, is responsible for generating approximately 90% of total cellular energy and harbors a unique genome (mtDNA). This genome is composed of 13 essential protein-coding genes involved in oxidative phosphorylation, which is vital to ATP production. The electron transport system encompasses five complexes, four of which are encoded by the mtDNA. Despite their critical role, mtDNA influence on growth and feed efficiency in cattle is underexplored. Investigating variation in the mtDNA may provide insight into its role in feed efficiency, growth performance, and overall productivity of beef cattle. Data from 531 beef steers (composite Simmental, Red Angus, and Gelbvieh) from a primarily closed herd at UNL was used to identify mitochondrial variation and its potential impact on average daily gain (ADG) and dry matter intake (DMI). Low pass sequencing (0.38X average autosomal coverage) was performed on 531 steers, achieving an average of 55X coverage of the mtDNA. Mitochondrial haplotypes on an additional 66 steers were determined from known maternal relationships for a total sample of 597. Data were trimmed and mapped (BWA-MEM) to the ARS-UCD2.0 cattle genome. Variants were called (GATK) and impacts were predicted (Ensembl VEP). Among all samples, nineteen nonsynonymous variants were identified; twelve variants were in Complex I genes (ND1-ND6), two in Complex III (CYTB), four in Complex IV (COX1-COX3), and one in Complex V (ATP6, ATP8). These variants were distributed into 17 haplotypes. A comprehensive evaluation of the mitochondrial haplotypes and their association with feed efficiency traits was conducted. Dry matter intake (DMI) and average daily gain (ADG) were measured for each animal using a GrowSafe system. Average DMI was 12.74±2.94 kg/d (n = 597) and ADG was 2.10±0.34 kg/d (n = 524). A linear mixed model was implemented to assess the impact of mitochondrial haplotype on ADG and DMI. The model accounted for age at harvest, mitochondrial haplotype, contemporary group (birth year and harvest cohort), and a genomic relationship matrix, constructed from approximately 90,000 autosomal single nucleotide polymorphisms. A suggestive association (P = 0.065) between mitochondrial haplotype and DMI indicates mitochondrial variation may influence feed intake in these steers. Increasing sample size from haplotypes represented by fewer animals is needed to better understand their effects. No association between ADG and mtDNA haplotypes was observed, suggesting that mitochondrial variation did not have a direct influence on growth rate in these animals. Future investigations of these relationships will include additional samples from within and outside of the UNL herd and will incorporate other growth and carcass metrics for a more comprehensive analysis of the relationships between growth performance and mitochondrial genotypes. These findings provide the first evidence that the mitochondrial genome plays a role in beef cattle growth efficiency.

The aim of this study was to assess individual differences in temperament and stress response and quantify their impact on feed efficiency, performance, and methane (CH4) emissions in beef cattle. Eighty-four steers (castrated males) (Charolais or Luing) were used. Temperament was assessed using two standardized tests: restlessness when restrained [crush score (CS)] and flight speed (FS) on release from restraint. Over a 56-day period individual animal dry matter intake (DMI) and weekly body weight was measured. Ultrasound fat depth was measured at the end of 56 days. Average daily gain (ADG), feed conversion ratio (FCR), and residual feed intake (RFI) were calculated. After the 56-day test period, animals were transported in groups of six/week to respiration chamber facilities. Blood samples were taken before and 0, 3, 6, and 9 h after transport. Plasma cortisol, creatine kinase (CK), glucose, and free fatty acids (FFA) were determined to assess physiological stress response. Subsequently, CH4 emissions were measured over a 3-day period in individual respiration chambers. CS (1.7 ± 0.09) and FS (1.6 ± 0.60 m/s) were repeatable (0.63 and 0.51, respectively) and correlated (r = 0.36, P < 0.001). Plasma cortisol, CK, and FFA concentrations increased after transport (P = 0.038, P = 0.006, and P < 0.001, respectively). Temperament (CS) and CK concentration were correlated (r = 0.29; P = 0.015). The extreme group analysis reveals that excitable animals (FS; P = 0.032) and higher stress response (cortisol, P = 0.007; FFA, P = 0.007; and CK, P = 0.003) were associated with lower DMI. ADG was lower in more temperamental animals (CS, P = 0.097, and FS, P = 0.030). Fat depth was greater in steers showing calmer CS (P = 0.026) and lower plasma CK (P = 0.058). Temperament did not show any relationship with RFI or CH4 emissions. However, steers with higher cortisol showed improved feed efficiency (lower FCR and RFI) (P < 0.05) and greater CH4 emissions (P = 0.017). In conclusion, agitated temperament and higher stress responsiveness is detrimental to productivity. A greater stress response is associated with a reduction in feed intake that may both increase the efficiency of consumed feed and the ratio of CH4 emissions/unit of feed. Therefore, temperament and stress response should be considered when designing strategies to improve efficiency and mitigate CH4 emissions in beef cattle.

Concerns about water availability, quality and accessibility have intensified. The livestock industry, particularly the beef sector, is under pressure to adopt more sustainable practices that optimize water usage while improving growth and feed efficiency. The objective of this study was to estimate the genetic parameters of traits associated with water efficiency, feed efficiency and growth in beef cattle. The data were collected from 916 seedstock bulls and heifers representing six breeds (Angus, Charolais, Hereford, Limousin, Simmental and Sim-Angus) in a facility equipped with Vytelle SENSE feed intake, water intake and in-pen body weight recording systems, located at the West Virginia University central testing facility in Wardensville, WV. The animals were part of six performance tests between November 2019 and September 2022, with an average age at the start of the test of 284 days, and an average test duration of 73 days. The rations were formulated to achieve 1.5 to 1.6 kg/d ADG (depending on the test) and had a high forage inclusion (&amp;gt;75% corn silage and &amp;gt;15% dry hay, as fed). The facility consists of 5 pens and animals were rotated every two weeks through the pens, so all animals are exposed to all pens. The phenotypes analyzed were average daily water intake (DWI), residual water intake (RWI), average daily dry matter intake (DMI), residual feed intake (RFI), and average daily gain (ADG). RWI and RFI were used to measure the water and feed efficiency of the animals. The genetic parameters were estimated with multi-trait animal models using Echidna mixed model software. In all models, breed, sex and the contemporary group (trial number and pen group) were included as fixed effects, the age at the start of the test was added as a covariate, and the animal was treated as a random effect. RWI and RFI were analyzed by adding ADG and metabolic mid-weight as additional covariates. The estimates of heritability for DWI, RWI, DMI, RFI and ADG were 0.49 (± 0.11), 0.40 (± 0.10), 0.35 (± 0.11), 0.16 (± 0.07) and 0.47 (± 0.11) respectively. Average daily water intake exhibited a positive genetic correlation with RWI (0.90), DMI (0.71), and ADG (0.76). On the other hand, the genetic correlation between RWI and RFI was not significantly different from zero, and genetic correlation between RWI and ADG was slightly positive. These results suggest that selecting for enhanced water efficiency in beef cattle can effectively decrease the daily water consumption without any adverse effect on feed efficiency, although it may have a small impact on growth. The complete genetic and phenotypic correlations are in Table 1. In conclusion, the traits associated with water intake and efficiency in beef cattle have a sizable genetic component and show potential for genetic improvement.

The great strain of increasing climate variability on animal agriculture necessitates improvement of current production processes, the development of methods to measure individual feed and water intakes, and the improvement of feed and water use efficiency in cattle. The use of machine learning (ML) approaches in predicting beef cattle dry matter intake (DMI) have provided groundwork for improvement of beef cattle production using big data and ML. However, despite wide variation between daily feed intakes, typical variables in animal intake-based ML approaches are not incremental, not allowing for daily prediction of intake. Our work introduces first-differenced intake, climate, and animal performance variables into a ML algorithm to predict beef cattle DMI and increase the immediacy of prediction applications. A total of 745 animals were evaluated in eight test groups from 11/25/2019 to 9/2/2021 in a dry lot equipped with In-Pen Weighing Positions and Feed and Water-Intake Nodes. Relationships among average daily gain (ADG), DMI, residual feed intake (RFI), water intake (WI), residual water intake (RWI), animal performance variables, and environmental variables at the individual animal level were investigated on a first test group of 125 Angus bulls and 53 crossbred steers. Out-Of-Bag root mean square error (OOB RMSE), an internal measure of Random Forest (RF) prediction accuracy, was used as a measure of error between model-predicted and observed DMI. Input variables were first-differenced by differencing a variable’s value between sequential test days for the entire test period. Two models were run using the RF package in R (ntree = 500, mtry = 11), with the first model (M1) using a standard test-train data split and the second model (M2) using all first-differenced and non-incremental observations to train the model. The model incorporating the test-train split performed marginally better than M2 (OOB RMSE = 1.39 and 1.44, respectively), indicating that first-differenced input variables can be used to predict daily individual DMI by within 1.39 kg by using M1. Using percent-increase in MSE (%IncMSE), first-differenced variables were found to be of less overall predictive value than non-incremental variables, with incremental daily gain and first-differenced water intake being ~55 and 45% less predictive than ADG and overall water intake in both M1 and M2. Though first-differenced variables were less predictive than non-incremental variables, inclusion of first-differenced variables allowed for prediction of individual DMI by within 1.39 kg. Our work demonstrates critical preliminary steps in the development of a deployable algorithm for the efficient prediction of DMI and the improvement of beef cattle intake efficiencies for the continued sustainability of animal agriculture.

Simple SummarySustainability in livestock production includes the use of strategies to reduce natural resource requirements. In this study, we investigated the relationship among feed efficiency, water efficiency, ingestive behavior, performance, and carcass traits in beef cattle. The results revealed interesting aspects of both feed efficiency and water efficiency on ingestive behavior and growth traits. The combined use of residual water intake and residual feed intake is an important option available for improving the environmental sustainability of beef cattle production that could be used in animal breeding programs.Feed and water efficiency are important traits to improve beef cattle production’s economic and environmental sustainability. This study evaluated residual feed intake (RFI) and residual water intake (RWI) and their relationship with performance, ingestive behavior, and carcass traits in Caracu beef cattle. The data were analyzed using a generalized linear model with least squares means. The ingestive behavior, performance, and carcass traits were influenced by sex (p < 0.05). Males showed higher dry matter intake (DMI), average daily gain (ADG), mid-test metabolic weight (BW0.75), rib eye area, and rump fat thickness than females, besides spending more time drinking and eating. Low RFI animals exhibited higher DMI than high RFI animals. Low RWI animals ingested 3.89 L/d of water further than high RWI animals. The interaction between sex and RWI influenced the DMI, BW0.75, and backfat thickness. The ingestive behavior of low and high RFI animals was similar, although high RWI animals visited a smaller number of drinkers than low RWI animals. Water intake positively affects productive efficiency, and the combined use of RWI and RFI may help improve the selection of more efficient animals contributing to reducing the costs of beef cattle production and improving environmental sustainability.

Effects of diet forage source and neutral detergent fiber content on milk production of dairy cattle and methane emissions determined using GreenFeed and respiration chamber techniques.

The objective of this study was to determine the effects of anesthetic and analgesic administration at castration on the dry matter and water intake, growth, feed efficiency, and carcass characteristics of beef steers. Angus (n = 14) and Simmental x Angus (n = 12) bulls (200 to 278 days of age) were randomly assigned to 2 treatments by breed. Control (CON) bulls were castrated by elastration with no pain management. Pain managed (PM) bulls were castrated by elastration, but also received an anesthetic (lidocaine + 10% sodium bicarbonate; 15 to 20 mL) injection and an oral analgesic (meloxicam; 0.992 mg per kg BW). Initial BW = 325.4 ± 36.9 kg and 299.3 ± 48.2 kg for CON and PM bulls, respectively. Steers were provided with ad libitum access to feed and water using an Insentec RIC system (Hokofarm, Marknesse, Netherlands). Beginning 2 weeks after castration, steers received 2 diets containing increasing energy concentrations at weekly intervals until reaching a finishing diet. Steers were implanted 28 d after castration. Dry matter intake (DMI), diet water intake (DWI), liquid water intake (LWI), and total water intake (TWI) were collected from d -7 to d 195. Depression scores were determined at 6, 18, and 30 h after castration. Body weights were collected on d -7, d 0, d 7, d 14, d 21, d 28, and d 195. Camera carcass data and USDA Yield and Quality Grades were collected at slaughter. Data were analyzed using the PROC MIXED procedure of SAS and significance was declared at P &amp;lt; 0.05. Dry matter intake, water intake, and BW were analyzed by periods beginning 1 week before castration (d -7 to d -1). Periods 2, 3, and 4 were the weeks following castration (d 0 to d 6, d 7 to d 13, and d 14 to d 20, respectively). Period 5 was from d 21 to d 195 and overall was from d 0 to d 195. Dry matter intake, DWI, LWI and TWI were unaffected by treatment. Average daily gain (P = 0.0178) and G:F (P = 0.0130) were influenced by treatment x period interactions. Pain managed steers gained faster (ADG: 1.26 vs 0.48 kg/d; P = 0.0069) and more efficiently (G:F: 0.148 vs 0.051; P = 0.0032) than CON cattle in the week following castration. Depression scores, carcass characteristics, overall ADG, and overall feed and water intake were not different. Pain management at time of castration improves ADG and G:F in the short term; however, the effects are not different over the duration of the feeding period. Further research is needed to determine the best method of castration pain management for beef cattle.

Water requirements of beef production can be reduced by genetic selection

Methane (CH4) emissions in ruminant systems are a loss of energy intake and a major contributor to climate change. This study evaluated the effects of increasing levels of non-protein nitrogen (NPN; 0.75, 1.5, and 3.0% dry matter basis) on enteric methane emissions and growth performance in finishing diets fed to beef steers. One hundred and eighty steers (IBW= 455 ± 41.5 kg) from 4 different sources were stratified by body weight (BW) and source and then randomly assigned to 1 of 4 NPN treatments. Steers were housed at Colorado State University’s Climate-Smart Research Facility. Daily gas flux and dry matter intake (DMI) were individually determined using SmartFeed and GreenFeed technologies (Rapid City, SD). Steers were acclimated for 35 days before a 13-day covariate period, where baseline CH4 emissions and feed intake data were collected. During the covariate period, a common finishing ration was fed (1.5% NPN treatment). Then, steers were fed their respective treatment for 53 days, and intake and methane emissions were measured continuously. Animal body weights were collected two consecutive days prior to beginning the NPN treatment and at the end of the experiment. Data were analyzed using R statistical software (4.4.3) and JMP (18.1.2), where NPN level, source, the interaction of source and NPN level, and covariate emissions and DMI were included in the model. Significance was declared at P &amp;lt; 0.05. Methane emissions were not different (P = 0.26) among treatments. However, CH4 yield (g/kg DMI) was greater (P &amp;lt; 0.05) for steers supplemented with 1.5% of NPN. Methane intensity (g/kg ADG) was greater (P&amp;lt; 0.05) for steers supplemented with 1.5% NPN treatment compared to those supplemented with 3.0% NPN. Steers supplemented with 0 and 0.75% of NPN had greater (P &amp;lt; 0.05) DMI than those supplemented with 1.5% NPN. Steers supplemented with 3.0% of NPN (P &amp;lt; 0.05) had intermediate DMI. Average daily gain (kg/d) was not different (P = 0.40) among treatments. Steers supplemented with 1.5% of NPN had a greater (P &amp;lt; 0.05) gain-to-feed ratio (G:F). In conclusion, increasing NPN levels in finishing diets can affect DMI, G:F, methane yield, and methane intensity without affecting ADG or enteric methane production.

Crossbreeding has been used to improve performance in beef cattle, however the effects of breed composition on methane (CH4) production, yield and intensity from cattle raised in tropical intensive and integrated systems remain unknown. To assess the impact of breed composition on performance and methane emissions, Nellore (NEL; yr 1: BW = 171.5 ± 19.4 kg; n = 10; yr 2: BW = 215.8 ± 32.3 kg, n = 25) and Angus x Nellore crossbred (AN; yr 1: BW = 214.2 ± 26.4 kg, n = 10; yr 2: BW = 242.5 ± 32.2 kg, n = 25) were compared. The animals grazed on integrated crop-livestock system in the growing phase (stocking rate 2452 kg BW/ha, herbage mass 4,884 kg dry matter (DM)/ha, forage allowance 5.9 kg DM/100kg BW) and then were finished in a feedlot. Steers (n = 8) from each breed composition were randomly selected in each phase to measure CH4 production using a sulfur hexafluoride (SF6) tracer technique and DM intake (DMI) using titanium dioxide. Compared with NEL, AN had both superior total gain and average daily gain (ADG) in the grazing period. The AN presented greater ADG in the feedlot with a shorter finishing period and resulted in greater carcass yield and carcass ADG. Methane production (kg/period) was lower in NEL (19% less) than AN in grazing (P<0.01), and no difference was observed in feedlot. The NEL had less CH4 intensity (CH4/BW) in grazing but greater CH4 per unit of ADG in the feedlot compared to AN. Breed composition did not influence the CH4 yield (CH4/DMI) in either phase, despite the difference in feedlot DMI (kg/day). In conclusion, crossbreeding may be an option to improve performance and reduce the CH4 per ADG in tropical climate conditions, resulting in lower methane emission per kg of meat produced.

In livestock production, the primary greenhouse gases (GHG) contributing to climate change are methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂). Reducing methane and nitrogen emissions is essential for enhancing the sustainability of beef cattle production systems. The objective of this study was to estimate heritabilities for CH₄, dry matter intake (DMI), and blood urea nitrogen (BUN), as well as estimate the genetic correlations between DMI and both CH4 and BUN in Angus [SS1] [MOU2] cattle to assess their potential as selection criteria for mitigating environmental impact. The dataset included measures for at least one of the traits on 1,036 Angus cattle, comprising both steers and heifers. Two bivariate animal models were utilized to estimate genetic parameters for DMI and CH₄, as well as for DMI and BUN.[ME3] For DMI, age and weaning weight were included as linear covariates in the statistical model, along with a contemporary group (CG) defined as a combination of start date, pen, and sex. For CH₄, the statistical model included age and CG as fixed effects, while for BUN, the effects of date, age, and weaning weight were incorporated. The heritability estimates for DMI, CH4, and BUN were found to be 0.22 ± 0.08, 0.32 ± 0.18, and 0.45 ± 0.24, respectively. Genetic correlations between DMI and CH4 and between DMI and BUN were calculated to be 0.78 ± 0.26 and 0.06 ± 0.31, respectively. The residual correlation between DMI and CH4 was estimated to be 0.37 ± 0.11, while the residual correlation between DMI and BUN was calculated to be -0.02 ± 0.17. The near-zero genetic correlation between DMI and BUN suggests that selection for reduced feed intake is unlikely to significantly impact circulating nitrogen metabolism. In contrast, the strong genetic correlation between DMI and CH₄ indicates that improving feed utilization could provide indirect environmental benefits by lowering CH4 emissions. However, the moderate heritability estimates for CH₄ and BUN suggest that direct selection for reduced CH4 production or nitrogen excretion may be more effective than relying solely on selection for lower DMI. These findings underscore the importance of incorporating multiple traits into genetic selection strategies to enhance both efficiency and environmental sustainability in beef cattle production.

There has been considerable interest in the use of red seaweed, and in particular Asparagopsis taxiformis, to increase production of cattle and to reduce greenhouse gas emissions. We hypothesized that feeding seaweed or seaweed derived products would increase beef or dairy cattle performance as indicated by average daily gain (ADG), feed efficiency measures, milk production, and milk constituents, and reduce methane emissions. We used meta-analytical methods to evaluate these hypotheses. A comprehensive search of Google Scholar, Pubmed and ISI Web of Science produced 14 experiments from which 23 comparisons of treatment effects could be evaluated. Red seaweed (Asparagopsis taxiformis) and brown seaweed (Ascophyllum nodosum) were the dominant seaweeds used. There were no effects of treatment on ADG or dry matter intake (DMI). While there was an increase in efficiency for feed to gain by 0.38 kg per kg [standardized mean difference (SMD) = 0.56; P = 0.001] on DerSimonian and Laird (D&L) evaluation, neither outcome was significant using the more rigorous robust regression analysis (P >0.06). The type of seaweed used was not a significant covariable for ADG and DMI, but A. nodosum fed cattle had lesser feed to gains efficiency compared to those fed A. taxiformis. Milk production was increased with treatment on weighted mean difference (WMD; 1.35 ± 0.44 kg/d; P <0.001); however, the SMD of 0.45 was not significant (P = 0.111). Extremely limited data suggest the possibility of increased percentages of milk fat (P = 0.040) and milk protein (P = 0.001) on (D&L) WMD evaluation. The limited data available indicate dietary supplementation with seaweed produced a significant and substantial reduction in methane yield by 5.28 ± 3.5 g/kg DMI (P = 0.003) on D&L WMD evaluation and a D&L SMD of −1.70 (P = 0.001); however, there was marked heterogeneity in the results (I2 > 80%). In one comparison, methane yield was reduced by 97%. We conclude that while there was evidence of potential for benefit from seaweed use to improve production and reduce methane yield more in vivo experiments are required to strengthen the evidence of effect and identify sources of heterogeneity in methane response, while practical applications and potential risks are evaluated for seaweed use.

Simple SummaryThe use of supplemental dietary nitrate (NO3−) to minimize enteric methane (CH4) emissions from ruminants is hindered by potential toxicity effects. In the current study, the potential effects of feeding encapsulated NO3− (EN), microencapsulated blend of essential oils (MBEO), and their combination on growth performance and enteric CH4 emissions of beef cattle were evaluated. There was no interaction effect between feeding EN and MBEO on CH4 emissions and the presence of MBEO did not affect the potential of EN to reduce CH4. Feeding MBEO increased CH4 emissions without affecting animal performance. Inclusion of EN as a replacement for urea reduced CH4 emissions without incurring any adverse effects on cattle health and performance.A long-term study (112 days) was conducted to examine the effect of feeding encapsulated nitrate (NO3−), microencapsulated blend of essential oils (EO), and their combination on growth performance, feeding behavior, and enteric methane (CH4) emissions of beef cattle. A total of 88 crossbred steers were purchased and assigned to one of four treatments: (i) control, backgrounding high-forage diet supplemented with urea (1.17% in dietary DM); (ii) encapsulated NO3− (EN), control diet supplemented with 2.5% encapsulated NO3− as a replacement for urea (1.785% NO3− in the dietary DM); (iii) microencapsulated blend of EO (MBEO), control diet supplemented with 150 mg/kg DM of microencapsulated blend of EO and pepper extract; and (iv) EN + MBEO, control diet supplemented with EN and MBEO. There was no interaction (p ≥ 0.080) between EN and MBEO on average dry matter intake (DMI), average daily gain (ADG), gain to feed ratio (G:F), feeding behavior, and CH4 emission (using GreenFeed system), implying independent effects of feeding EN and MBEO. Feeding MBEO increased CH4 production (165.0 versus 183.2 g/day; p = 0.005) and yield (18.9 versus 21.4 g/kg DMI; p = 0.0002) but had no effect (p ≥ 0.479) on average DMI, ADG, G:F, and feeding behavior. However, feeding EN had no effect on ADG and G:F (p ≥ 0.119) but reduced DMI (8.9 versus 8.4 kg/day; p = 0.003) and CH4 yield (21.5 versus 18.7 g/kg DMI; p < 0.001). Feeding EN slowed (p = 0.001) the feeding rate (g of DM/min) and increased (p = 0.002) meal frequency (events/day). Our results demonstrate that supplementing diets with a blend of EO did not lower CH4 emissions and there were no advantages of feeding MBEO with EN. Inclusion of EN as a replacement for urea reduced CH4 emissions but had no positive impact on animal performance.

Effects of the investigational methane (CH4) inhibitor 3-nitrooxypropanol (3-NOP) on animal performance, health and enteric CH4 production of beef cattle were evaluated in a commercial feedlot. Two concurrent studies were conducted: a large pen study (4,048 cattle, eight pen replicates per experimental group) to measure animal performance and health and a small pen study (a subset of 50 cattle from the large pen study, n = 25 per experimental group) to measure enteric CH4 emissions. Within the study, animals (body weight ± SD, 282 ± 8 kg) were assigned in a completely randomized design to one of two groups: control, fed a backgrounding diet (70% corn or barley silage, 30% steam-flaked barley grain concentrate; dry matter (DM) basis) and 3-NOP, fed the backgrounding diet containing 3-NOP. The treatment group in the large pen study was adapted to 3-NOP (12 ± 3 d) before receiving the final target level of 200 mg/kg of DM, which was fed for 108 ± 8 d. Animals in the small pen CH4 emissions study received a basal diet or a basal diet with 3-NOP, with the dose increased every 28 d: low (150 mg/kg DM; 1.27 g/d), medium (175 mg/kg DM; 2.25 g/d), and high (200 mg/kg DM; 2.75 g/d). Intake in the small pens was monitored by electronic feeding bunks and CH4 was measured using the GreenFeed system. In the large pen study, total weight gained, average daily gain, and animal health variables were not affected by 3-NOP, but DM intake (DMI) tended to decrease (P = 0.06) by 2.6% relative to control (8.07 kg/d), while gain:feed ratio tended to be improved (P = 0.06) by 2.5% relative to control (0.161 kg weight gain/kg DMI). In the small pen study, average daily consumption of 3-NOP increased with inclusion rate whereas average DMI was decreased by 5.4% (P = 0.02) compared with control (10.4 kg/d). On average, addition of 3-NOP decreased (P = 0.001) CH4 emissions (g/d) by 25.7% and yield (g CH4/kg DMI) by 21.7%. In conclusion, supplementing a backgrounding diet with 3-NOP decreased CH4 yield and tended to improve feed efficiency of beef cattle fed in a commercial feedlot with no negative impacts on animal health.