Residual Feed Intake as an Efficiency Metric for Pre-Weaning Dairy Calves: What Do We Know?

Dairy cattle systems have targeted improvements in feed efficiency by selecting animals that can convert less feed into more products. Residual feed intake (RFI) has been the index of choice when selecting dairy cattle for feed efficiency. Nonetheless, RFI studies have focused on lactating cows, and the crucial importance of pre-weaning efficiency on farm profitability and cow productivity has been mostly neglected. This review discusses the current knowledge of how RFI divergence relates to nutrient metabolism in pre-weaning dairy calves, including the advantages and limitations of evaluating RFI in this phase. Existing literature indicates that nutrient utilization, energy metabolism, protein metabolism, vitamin metabolism, intestinal development, and hindgut bacterial populations may be implicated in RFI divergence between pre-weaning calves. Techniques developed to date to evaluate RFI in this phase are still evolving to better adapt to the unique characteristics of this phase, and more research is needed to fill in the gaps in our current understanding of early-life feed efficiency divergence in cattle. However, current results suggest great potential for selecting high-efficiency calves while in pre-weaning to accelerate the progress of genetic selection in dairy cattle.

Assessment of heat production and methane emission using infrared thermography in lactating Holstein and Gyrolando-F1 (½ Holstein ½ Gyr) crossbreed cows.

Infrared thermography (IRT) is a non-invasive and efficient tool to detect changes in the animal's body surface temperature, which is directly associated with the animal's energy loss. Methane emission represents a significant energy loss, particularly in ruminants, as well as heat production. Therefore, the aim of this study was to correlate skin temperature measured using IRT with heat production (HP) and methane emission in lactating Holstein and crossbred ½ Holstein x ½ Gyr (Gyrolando-F1) cows. Six Gyrolando-F1 and four Holstein cows, all primiparous, at mid lactation were used to evaluate daily HP and methane emission using indirect calorimetry in respiratory chambers. Thermographic images were taken at anus, vulva, ribs (on the right side), left flank, right flank, right front foot, upper lip, masseter and eye; IRT was performed every hour during 8 h after the morning feeding. Cows received the same diet ad libitum. Daily methane emission was positively correlated with IRT taken at the right front foot 1 h after feeding in Gyrolando-F1 cows (r = 0.85, P < 0.05) and with IRT taken at the eye 5 h after feeding in Holstein cows (r = 0.88, P < 0.05). HP was positively correlated with IRT taken at the eye 6 h after feeding in Gyrolando-F1 cows (r = 0.85, P < 0.05) and with IRT taken at the eye 5 h after feeding in Holstein cows (r = 0.90, P < 0.05). Infrared thermography was positively correlated with HP and methane emission in both Holstein and Gyrolando-F1 lactating cows, although the anatomical points and times of image acquisition yielding the greatest correlation coefficients varies among breeds.

Effects of dairy cow temperament on milk yield: a systematic review and meta-analysis.

The temperament of dairy cows interferes in milk yield and quality, but there is a lack of consensus throughout the literature. Thus, systematic review (SR) and meta-analysis (MA) methodologies were used to assess the effects of dairy cow temperament on milk yield. Our literature search included four electronic databases (CABI Abstracts, Web of Science, PubMed, and Scopus) and bibliographies of the publications included on MA. As inclusion criteria, we considered publications about the temperament of lactating cows and its effect on daily milk yield and total milk yield (whole lactation). A random effect-MA was carried out separately for daily milk yield and total milk yield related to each class of cows' temperament, 'low' (low reactivity, calm animals), 'intermediate' (intermediate reactivity), and 'high' (high reactivity, reactive animals). A total of eight publications reporting 75 trials were included in the analyses for daily milk yield, and three publications reporting nine trials for total milk yield. For daily and total milk yield the heterogeneity between publications was high (I2 = 99.9%). Cows of European breeds with intermediate temperament produced less milk daily than the calm (P = 0.020) and reactive ones (P < 0.001). In the case of primiparous cows, those with intermediate temperament produced less milk daily (P < 0.001) than the reactive ones, while for multiparous, the intermediate produced less than calm (P = 0.032) and reactive cows (P < 0.001). Regarding the stage of lactation, cows evaluated throughout lactation with a calm temperament tended (P = 0.081) to produce more milk than the intermediate ones, but less than the reactive ones (P < 0.001). For total milk yield, reactive cows tended to produce more than the calm (P = 0.082) and intermediate (P = 0.001) ones. Among European and primiparous cows, reactive cows produced more than the intermediate (P = 0.001). According to our results, we cannot confirm what we expected, that calmer cows would be the most productive for both daily and total yield.

Individual differences in the behavior of dairy cows can affect their productive performance. In an attempt to summarize the scientific information available, we conducted a systematic review and meta-analysis to identify the effects of dairy cows' temperament on milk yield. We hypothesize that calmer cows would produce more milk. We found nine publications with quantitative data available to be included in a meta-analysis. Eight additional publications that addressed the topic of interest but did not present data enough to be included in the meta-analysis (i.e., evaluated the relationships between temperament and milk yield using correlations or regressions) were used to perform a qualitative synthesis. The results of our meta-analysis indicated that the reactive cows were more productive than the calm or intermediate ones, contradicting our initial hypothesis. According to the results of the qualitative synthesis, most of the publications reported a negative association between reactive temperament and milk yield, indicating that calmer cows would produce more milk. We concluded that there are divergences in the information available about the temperament and production of dairy cows. We highlight the need for greater methodological and analytical standardization to allow a broader quantitative synthesis of the temperament effects on milk yield.

Severe influenza infection is associated with inflammatory programmed cell death in infected macrophages.

Introduction: Influenza A virus (IAV) is one of the leading causes of respiratory tract infections in humans, representing a major public health concern. The various types of cell death have a crucial role in IAV pathogenesis because this virus may trigger both apoptosis and necroptosis in airway epithelial cells in parallel. Macrophages play an important role in the clearance of virus particles, priming the adaptive immune response in influenza. However, the contribution of macrophage death to pathogenesis of IAV infection remains unclear. Methods: In this work, we investigated IAV-induced macrophage death, along with potential therapeutic intervention. We conducted in vitro and in vivo experiments to evaluate the mechanism and the contribution of macrophages death to the inflammatory response induced by IAV infection. Results: We found that IAV or its surface glycoprotein hemagglutinin (HA) triggers inflammatory programmed cell death in human and murine macrophages in a Toll-like receptor-4 (TLR4)- and TNF-dependent manner. Anti-TNF treatment in vivo with the clinically approved drug etanercept prevented the engagement of the necroptotic loop and mouse mortality. Etanercept impaired the IAV-induced proinflammatory cytokine storm and lung injury. Conclusion: In summary, we demonstrated a positive feedback loop of events that led to necroptosis and exacerbated inflammation in IAV-infected macrophages. Our results highlight an additional mechanism involved in severe influenza that could be attenuated with clinically available therapies.

Potential benefits of a blend of essential oils on metabolism, digestibility, organ development and gene expression of dairy calves.

The objective of this study was to evaluate blood cells and metabolites, insulin-like growth factor-1 (IGF-1), digestibility, internal organs weight and histology, gene expression, and spleen cell proliferation of pre-weaned bull calves supplemented with a blend of essential oils in milk replacer (MR). Sixteen newborn Holstein × Gyr crossbred dairy bull calves, with body weight at birth of 33.3 ± 3.7 kg, were housed in individual sand bedded pens, blocked by genetic composition, and randomly assigned to 1 of 2 treatments in a randomized complete block design: Control (CON, n = 8) and blend of essential oils supplementation (BEO, n = 8, 1 g/day/calf, Apex Calf, Adisseo, China). The commercial blend was composed by plant extracts derived from anise, cinnamon, garlic, rosemary, and thyme. Animals were fed 5 L of MR/day reconstituted at 15% (dry matter basis), divided into two equal meals. Water and starter were provided ad libitum. ß-hydroxybutyrate, urea, and glucose were evaluated weekly, IGF-1 was evaluated biweekly, and total blood cell count was performed every four weeks until the end of the trial at eight weeks of age. Feed samples were collected three times a week and polled for weekly analysis. Apparent total nutrient digestibility was determined from d 56 to 60 of age. On d 60 ± 1, animals were euthanized for organ weight, histology, spleen cell proliferation, and intestinal gene expression analysis. Data were analyzed independently using linear mixed models using the REML method in the nlme package in R for continuous outcomes. A non-parametric test was used for ordered categorical outcomes using the Artools package in R. There were no differences between groups for blood evaluations, digestibility, gene expression, and a spleen cell proliferation assay. However, BEO calves presented a heavier pancreas, heavier intestines, bigger ileum villi, and higher cecum butyrate levels (P < 0.05), demonstrating that the EO supplementation helped intestinal development and symbiotic bacteria. It was also observed in CON animals' heavier respiratory tract and a higher eosinophil count (P < 0.05). Therefore, the organs where eosinophils are more active had a better response for BEO animals. No differences were found in the intestinal gene expression in the immune context. These results demonstrate that supplementing essential oils in MR could contribute to gut development and immune function. However, more research is needed to understand its impact on body development and define the best dosage and route of administration.

Platelet proteome reveals features of cell death, antiviral response and viral replication in covid-19.

Coronavirus disease 2019 (COVID-19) has affected over 400 million people worldwide, leading to 6 million deaths. Among the complex symptomatology of COVID-19, hypercoagulation and thrombosis have been described to directly contribute to lethality, pointing out platelets as an important SARS-CoV-2 target. In this work, we explored the platelet proteome of COVID-19 patients through a label-free shotgun proteomics approach to identify platelet responses to infection, as well as validation experiments in a larger patient cohort. Exclusively detected proteins (EPs) and differentially expressed proteins (DEPs) were identified in the proteomic dataset and thus classified into biological processes to map pathways correlated with pathogenesis. Significant changes in the expression of proteins related to platelet activation, cell death, and antiviral response through interferon type-I were found in all patients. Since the outcome of COVID-19 varies highly among individuals, we also performed a cross-comparison of proteins found in survivors and nonsurvivors. Proteins belonging to the translation pathway were strongly highlighted in the nonsurvivor group. Moreover, the SARS-CoV-2 genome was fully sequenced in platelets from five patients, indicating viral internalization and preprocessing, with CD147 as a potential entry route. In summary, platelets play a significant role in COVID-19 pathogenesis via platelet activation, antiviral response, and disease severity.

Platelet-monocyte interaction amplifies thromboinflammation through tissue factor signaling in COVID-19.

Accumulating evidence into the pathogenesis of COVID-19 highlights a hypercoagulability state with high risk of life-threatening thromboembolic complications. However, the mechanisms of hypercoagulability and their link to hyperinflammation remain poorly understood. Here, we investigate functions and mechanisms of platelet activation and platelet-monocyte interactions in inflammatory amplification during SARS-CoV-2 infection. We used a combination of immunophenotyping, single-cell analysis, functional assays, and pharmacological approaches to gain insights on mechanisms. Critically ill patients with COVID-19 exhibited increased platelet-monocyte aggregates formation. We identified a subset of inflammatory monocytes presenting high CD16 and low HLA-DR expression as the subset mainly interacting with platelets during severe COVID-19. Single-cell RNA-sequencing analysis indicated enhanced fibrinogen receptor Mac-1 in monocytes from patients with severe COVID-19. Monocytes from patients with severe COVID-19 displayed increased platelet binding and hyperresponsiveness to P-selectin and fibrinogen with respect to tumor necrosis factor-α and interleukin-1ß secretion. Platelets were able to orchestrate monocyte responses driving tissue factor (TF) expression, inflammatory activation, and inflammatory cytokines secretion in SARS-CoV-2 infection. Platelet-monocyte interactions ex vivo and in SARS-CoV-2 infection model in vitro reciprocally activated monocytes and platelets, inducing the heightened secretion of a wide panel of inflammatory mediators. We identified platelet adhesion as a primary signaling mechanism inducing mediator secretion and TF expression, whereas TF signaling played major roles in amplifying inflammation by inducing proinflammatory cytokines, especially tumor necrosis factor-α and interleukin-1ß. Our data identify platelet-induced TF expression and activity at the crossroad of coagulation and inflammation in severe COVID-19.

Adoption of Precision Technologies by Brazilian Dairy Farms: The Farmer's Perception.

The use of precision farming technologies, such as milking robots, automated calf feeders, wearable sensors, and others, has significantly increased in dairy operations over the last few years. The growing interest in farming technologies to reduce labor, maximize productivity, and increase profitability is becoming noticeable in several countries, including Brazil. Information regarding technology adoption, perception, and effectiveness in dairy farms could shed light on challenges that need to be addressed by scientific research and extension programs. The objective of this study was to characterize Brazilian dairy farms based on technology usage. Factors such as willingness to invest in precision technologies, adoption of sensor systems, farmer profile, farm characteristics, and production indexes were investigated in 378 dairy farms located in Brazil. A survey with 22 questions was developed and distributed via Google Forms from July 2018 to July 2020. The farms were then classified into seven clusters: (1) top yield farms; (2) medium-high yield, medium-tech; (3) medium yield and top high-tech; (4) medium yield and medium-tech; (5) young medium-low yield and low-tech; (6) elderly medium-low yield and low-tech; and (7) low-tech grazing. The most frequent technologies adopted by producers were milk meters systems (31.7%), milking parlor smart gate (14.5%), sensor systems to detect mastitis (8.4%), cow activity meter (7.1%), and body temperature (7.9%). Based on a scale containing numerical values (1-5), producers indicated "available technical support" (mean; σ2) (4.55; 0.80) as the most important decision criterion involved in adopting technology, followed by "return on investment-ROI" (4.48; 0.80), "user-friendliness" (4.39; 0.88), "upfront investment cost" (4.36; 0.81), and "compatibility with farm management software" (4.2; 1.02). The most important factors precluding investment in precision dairy technologies were the need for investment in other sectors of the farm (36%), the uncertainty of ROI (24%), and lack of integration with other farm systems and software (11%). Farmers indicated that the most useful technologies were automatic milk meters systems (mean; σ2) (4.05; 1.66), sensor systems for mastitis detection (4.00; 1.57), automatic feeding systems (3.50; 2.05), cow activity meter (3.45; 1.95), and in-line milk analyzers (3.45; 1.95). Overall, the concerns related to data integration, ROI, and user-friendliness of technologies are similar to those of dairy farms located in other countries. Increasing available technical support for sensing technology can have a positive impact on technology adoption.

Effects of vaccination against brucellosis and clostridia on the intake, performance, feeding behavior, blood parameters, and immune responses of dairy heifers calves.

The aim of this study was to identify possible effects of different vaccination strategies (concomitantly or not) against brucellosis and clostridia on intake, performance, feeding behavior, blood parameters, and immune responses of dairy heifers calves. Fifty heifers calves were enrolled [38 Gyr (Zebu, Bos taurus indicus) and 12 5/8 Holstein × Gyr]. At 120 d of age, animals were randomly distributed among 3 groups: B (n = 18), vaccinated against brucellosis; C (n = 14), vaccinated against clostridia and CB (n = 18), vaccinated concomitantly for both. Rectal and thermographic temperatures were evaluated on days -1, 0, 1, 2, 3, 5, 7,10, 14, and 28 relatives to the vaccination day. Feed and water intake, body weight (BW), and feeding behavior were monitored daily by an electronic feeding system. Blood was sampled on days 0, 3, 7, 14, and 28, relative to the vaccination day for determination of glucose and ß -hydroxybutyrate (BHBA) concentrations. Blood sampled on day 0 (prevaccination) and on days 28 and 42 were used to evaluate the immune response against Brucella abortus and clostridia. There was an increase in rectal temperature between the first and the third day postvaccination in the 3 groups. The thermography revealed an increase of local temperature for 7 d on groups B and CB. Group C had increased local temperature for a longer period, lasting for up to 14 d. Dry mater intake was reduced for groups B and CB, but no alteration was observed for group C. No alterations regarding initial BW, final BW, average daily weight gain, and feed efficiency were observed. No differences were observed for the 3 vaccination groups for blood parameters throughout the evaluation period. The concomitant vaccination against brucellosis and clostridia led to lower neutralizing antibody titers against epsilon toxin of Clostridium perfringens and botulinum toxin type C of C. botulinum (C > CB > B). When cellular proliferation assay and serological tests to B. abortus were evaluated, no differences were observed between groups B and CB. The present results indicate that the concomitant vaccination against brucellosis and clostridia has no relevant impact on the intake, performance, and feeding behavior of dairy calves. However, the concomitant vaccination of vaccines against these 2 pathogens impacts animal immunity against clostridial infections.

Effects of Feeding Level and Breed Composition on Intake, Digestibility, and Methane Emissions of Dairy Heifers.

The dairy Nutrients Requirements of Cattle (NRC) was developed using data from purebred Holsteins and it might not accurately predict the performance of crossbred cattle. Our objectives were to evaluate the effects of two feeding levels (FLs) and three breed compositions (BCs) on nutrient intake, digestibility, performance, and methane (CH4) emissions of prepubertal dairy heifers. We used thirty-six heifers from three BCs: purebred Holstein (H), purebred Gyr (G), and F1 Holstein × Gyr (HG). Each BC had 12 animals and the experiment was designed as twelve incomplete three by three Latin squares, in a factorial arrangement three by two, with three BCs and two FLs (400 and 800 g/day). Total tract nutrient digestibility was determined using total fecal collection and DMI was individually measured. The data were analyzed using the PROC MIXED in SAS. Dry matter intake of all nutrients increased from the medium to high feeding level and the nutrients digestibility coefficients did differ among BCs. Achieved body weight gain in the medium FL treatment was greater than those predicted using the NRC, suggesting that crossbred and Gyr heifers have similar performance to Holsteins. Breed composition does not influence body weight gain of confined dairy heifers, but Holstein heifers fed a medium FL had higher feed efficiency and reduced CH4 emissions intensity.

Replacement of Soybean Meal With Soybean Cake Reduces Methane Emissions in Dairy Cows and an Assessment of a Face-Mask Technique for Methane Measurement.

The objective of this study was to (a) evaluate the effect of replacing soybean meal (SBM) with soybean cake (SBC) on feeding behavior, rumen fermentation, milk production, nutrient digestibility and CH4 emissions and (b) investigate whether a face-mask technique could be used to predict daily methane (CH4) emissions in dairy cattle. The experiment was conducted as a completely randomized design, with 32 crossbred Holstein × Gyr cows (days in milk (DIM): 112 ± 25.1) randomly assigned to the following treatments (n = 8/group) for 75 days: (1) 0% SBC, (2) 6% SBC, (3) 14% SBC, and (4) 23% SBC, in place of SBM on a dry matter (DM) basis. Across the final 4 weeks of the study, CH4 production was estimated using the proposed face-mask technique subsequent to a respiration chamber measurement for an evaluation of treatment efficacy and face-mask accuracy. There was no effect of SBM replacement by SBC on intake, feeding or drinking behavior (P > 0.21). Total VFA concentration, the individual proportions of VFA and blood metabolites were not altered (P > 0.17) by SBC, however there was a tendency for decreased (P = 0.08) lactate and plasma urea nitrogen (P = 0.07) concentration associated with SBC addition. Fat-corrected milk yield (FCM4%) and composition was not affected (P > 0.27) by SBC; however, there was a tendency for decreased total milk solids (P = 0.07) and milk fat (P = 0.08) associated with 23% SBC treatment. There was no treatment × technique interaction (P > 0.05) effect on gas measurements. A maximum reduction (P = 0.01) in CH4 yield (g/kg DM) and intensity (g/kg milk) of 11 and 20%, respectively, was observed for the 14% SBC inclusion. Compared to the week of mask measurements, chambers decreased (P = 0.01) intake (kg/d, %BW) and increased (P = 0.05) FCM4%. The face-mask method over estimated O2 consumption by 5%. The face-mask method accurately predicted daily CH4 emissions when compared to the chamber at the same time-point. However, there was a linear bias of CH4 outputs so further evaluation of the calculation of total CH4 from a spot measurement is required.

Unconventional Vegetable Oils for a Reduction of Methanogenesis and Modulation of Ruminal Fermentation.

The objective of this study was to evaluate the use of vegetable oils from plants grown in Brazil, first using the in vitro batch culture, and then evaluating the oil with methane (CH4) reducing potential in an in vivo experiment. The in vitro experiment was conducted as a completely randomized design using the seven contrasting oils. Treatments consisted of a control and 3 increasing concentrations (0, 1, 2, and 5% v/v) of oil added to a tifton 85 hay samples. All vegetable oils linearly decreased (P < 0.01) gas production after 24 h of incubation, with the greatest reduction when 5% of oil was included into the diet. Açaí and buriti had no effect of CH4 (% or mL/g DM incubated) however carrot, macaúba, basil, passionflower, and pequi oil all linearly decreased (P < 0.01) CH4 production with increasing inclusion rate of oil. Pequi oil resulted in the largest decrease in CH4 production (mL/g DM incubated) after 24 h of in vitro incubation. The objective of the in vivo experiment was to evaluate the effects of pequi oil on nutrient digestibility, CH4 production, and rumen fermentation parameters in wethers fed a hay-based diet. The experiment was conducted as a 2 × 2 Latin Square design using 4 Dorper wethers (63.4 ± 1.46 kg body weight). There were 2 experimental periods of 21 d each, with d 1-14 used for diet adaptation and d 15-21 for measurements and collections. The treatments consisted of a control diet and pequi oil fed at 70 g per animal per day. The addition of pequi oil to the diet had no effect on feed intake or the digestibility of nutrients, however there was a numerical decrease in the population of cellulolytic bacteria. There was a tendency (P = 0.06) for pequi oil addition to decrease CH4 production (g/d) by 17.5%. From this study, we can conclude that pequi oil may be used as a suitable oil for reducing CH4 production from ruminants, with no negative effects on intake or digestibility.

Enteric methane mitigation strategies in ruminants: a review / Estrategias de mitigación de metano entérico en rumiantes: revisión de literatura / Estratégias de mitigação de metano entérico em ruminantes: revisão de literatura

Livestock farming in Latin America has been criticized because of its large greenhouse gas (GHG) production resulting from the use of degraded forage and low-efficiency production performance. Agriculture contributes a significant amount of the three main greenhouse gases: methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). Methane has a global warming potential 25 times greater than CO2. Enteric methane is an important greenhouse gas responsible for approximately 15% of global warming. The trend and legal obligation of mitigating greenhouse gas emissions will likely directly influence improved efficiency of livestock systems, including animal nutrition and handling. The development of mitigation strategies and the viability of their practical applications have been researched around the world. Various nutritional strategies to mitigate enteric methane have been studied and developed. All of them differ in terms of viability, cost, and acceptance by the producers. Their adoption should be based on the capacity to reduce methane emissions in association with economic viability and animal performance. Animal performance improvement will be achieved in production systems (mainly those related to efficient forage use) associated with good management of nutrition, health and reproduction. These are important strategies to consolidate Brazil as a food producer to the world, respecting the demands regarding land, water, biodiversity conservation and emission of greenhouse gases.

La industria pecuaria latinoamericana ha sido criticada por la emisión significativa de gases con efecto invernadero (GHG). Dicha crítica se fundamenta en los bajos indicadores zootécnicos observados en los sistemas de producción animal basados en pasturas degradadas o que se encuentran por debajo de su potencial de producción. La industria agropecuaria contribuye de manera significativa con la emisión de los tres principales GHG: metano (CH4), dióxido de carbono (CO2) y óxido nitroso (NO2). El gas metano tiene un potencial de calentamiento global 25 veces mayor que el de CO2. El metano entérico es un importante gas de efecto invernadero, que es responsable de aproximadamente el 15% del calentamiento global. La tendencia o la obligación legal de mitigar las emisiones de GHG tendrá una influencia directa sobre la necesidad del aumento de la eficiencia zootécnica en los sistemas pecuarios relacionado con el manejo nutricional de los animales que deberá ser adoptado. El desarrollo de estrategias de mitigación y la viabilidad de su aplicación práctica representan áreas de investigación alrededor del mundo. Existen diversas estrategias nutricionales que se han estudiado y desarrollado con el fin de mitigar el metano entérico. Dichas estrategias presentan diferentes viabilidades, costos y posibilidades para que sean aceptadas por los productores. La elección de la estrategia de mitigación a ser adoptada deberá estar centrada en la capacidad de reducción de las emisiones de metano asociada con la viabilidad económica y el mantenimiento del desempeño animal. El aumento de los indicadores zootécnicos que se obtendrán en los sistemas de producción (principalmente aquellos que utilicen de manera eficiente el forraje) asociado a una buena nutrición, salud y manejo reproductivo, son estrategias importantes para la consolidación de Brasil como un importante productor de alimentos para el mundo, teniendo en cuenta las demandas relacionadas con el uso del suelo, del agua, la conservación de la biodiversidad y de la emisión de gases con efecto invernadero.

A pecuária da América Latina tem sido criticada por emitir quantidades significativas de gases de efeito estufa (GHG). Tal crítica tem sido fundamentada nos baixos índices zootécnicos verificados em sistemas de exploração animal baseados em pastagens degradadas ou que se encontram abaixo do seu potencial de produção. A agropecuária contribui de forma significativa com a emissão dos três principais GHG: metano (CH4), dióxido de carbono (CO2) e óxido nitroso (NO2). O gás metano apresenta potencial de aquecimento global 25 vezes maior que o CO2. O metano entérico é um importante gás de efeito estufa, que é responsável por aproximadamente 15% do aquecimento global. A tendência ou obrigação legal de mitigar as emissões de GHG influenciará diretamente a necessidade de aumento da eficiência zootécnica nos sistemas pecuários, atrelado ao manejo nutricional dos animais a ser adotado. O desenvolvimento de estratégias de mitigação e a viabilidade da aplicação prática dessas estratégias são áreas atuais de pesquisa em todo o mundo. Existem várias estratégias de nutrição para mitigar metano entérico que têm sido estudados e desenvolvidos. Todos estes têm diferentes viabilidades, custos e possibilidades de serem adotadas pelos produtores. A escolha de qual vai ser utilizado deve basear-se na capacidade de reduzir as emissões de metano associadas com viabilidade econômica e a manutenção do desempenho do animal. O aumento nos índices zootécnicos que serão obtidos em sistemas de produção (principalmente os relacionados ao uso de forragem eficiente) associada a uma boa nutrição, saúde e manejo reprodutivo são estratégias importantes para consolidar o Brasil como um importante produtor de alimentos para o mundo, respeitando as demandas relacionadas ao uso da terra, da água, da conservação da biodiversidade e da emissão de gases de efeito estufa.