Brazil has the largest herd of beef cattle in the world, estimated at approximately 200 million animals. Production is predominantly pasture-based and low input and hence time to slaughter is long, which promotes high methane (CH 4) emissions per kg of product. The objective of this study was to investigate the impact of increasing animal productivity using fertilizers, forage legumes, supplements and concentrates, on the emissions of greenhouse gases (GHGs) in five scenarios for beef production in Brazil. A life cycle analysis (LCA) approach, from birth of calves to mature animals ready for slaughter at the farm gate, was utilized using Tier 2 methodologies of the IPCC and the results expressed in equivalents of carbon dioxide (CO 2 eq) per kg of carcass produced. Fossil CO 2 emitted in the production of supplements, feeds and fertilizers was included using standard LCA techniques. The first four scenarios were based solely on cattle production on pasture, ranging from degraded Brachiaria pastures, through to a mixed legume/Brachiaria pasture and improved N-fertilized pastures of Guinea grass (Panicum maximum). Scenario 5 was the most intensive and was also based on an N-fertilized Guinea grass pasture, but with a 75-day finishing period in confinement with total mixed ration (TMR). Across the scenarios from 1 to 5 the increase in digestibility promoted a reduction in the forage intake per unit of animal weight gain and a concomitant reduction in CH 4 emissions. For the estimation of nitrous oxide (N 2 O) emissions from animal excreta, emission factors from a study in the Cerrado region were utilized which postulated lower emission from dung than from urine and much lower emissions in the long dry season in this region. The greatest impact of intensification of the beef production systems was a 7-fold reduction of the area necessary for production from 320 to 45 m 2 /kg carcass. Carcass production increased from 43 to 65 Mg per herd across the scenarios from 1 to 5, and total emissions per kg carcass were estimated to be reduced from 58.3 to 29.4 kg CO 2 eq/kg carcass. Even though animal weight gain was lower in the mixed grass-legume scenario (3) than for the N-fertilized Guinea grass pastures (scenarios 4 and 5) GHG emissions per kg carcass were similar as the legume N 2 fixation input had no fossil-fuel cost. A large source of uncertainty for the construction of such LCAs was the lack of data for enteric CH 4 emissions from cattle grazing tropical forages.

The objective of this study was to determine the effect of dietary nitrate on methane emission and rumen fermentation parameters in Nellore × Guzera (Bos indicus) beef cattle fed a sugarcane based diet. The experiment was conducted with 16 steers weighing 283 ± 49 kg (mean ± SD), 6 rumen cannulated and 10 intact steers, in a cross-over design. The animals were blocked according to BW and presence or absence of rumen cannula and randomly allocated to either the nitrate diet (22 g nitrate/kg DM) or the control diet made isonitrogenous by the addition of urea. The diets consisted of freshly chopped sugarcane and concentrate (60:40 on DM basis), fed as a mixed ration. A 16-d adaptation period was used to allow the rumen microbes to adapt to dietary nitrate. Methane emission was measured using the sulfur hexafluoride tracer technique. Dry matter intake (P = 0.09) tended to be less when nitrate was present in the diet compared with the control, 6.60 and 7.05 kg/d DMI, respectively. The daily methane production was reduced (P < 0.01) by 32% when steers were fed the nitrate diet (85 g/d) compared with the urea diet (125 g/d). Methane emission per kilogram DMI was 27% less (P < 0.01) on the nitrate diet (13.3 g methane/kg DMI) than on the control diet (18.2 g methane/kg DMI). Methane losses as a fraction of gross energy intake (GEI) were less (P < 0.01) on the nitrate diet (4.2% of GEI) than on the control diet (5.9% of GEI). Nitrate mitigated enteric methane production by 87% of the theoretical potential. The rumen fluid ammonia-nitrogen (NH(3)-N()) concentration was significantly greater (P < 0.05) for the nitrate diet. The total concentration of VFA was not affected (P = 0.61) by nitrate in the diet, while the proportion of acetic acid tended to be greater (P = 0.09), propionic acid less (P = 0.06) and acetate/propionate ratio tended to be greater (P = 0.06) for the nitrate diet. Dietary nitrate reduced enteric methane emission in beef cattle fed sugarcane based diet.

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Resumo -O objetivo deste trabalho foi avaliar metas de manejo para capim-marandu (Urochloa brizantha cv. Marandu) submetido a pastejo rotativo e a doses de nitrogênio, de janeiro de 2009 a abril de 2010. Os tratamentos consistiram da combinação de duas frequências de pastejo (altura pré-pastejo de 25 e 35 cm) e de duas doses de fertilizante nitrogenado (50 e 200 kg ha -1 por ano) em delineamento de blocos ao acaso com arranjo fatorial 2x2 e quatro repetições. A altura de pós-pastejo estipulada foi de 15 cm. Maiores valores de ganho de peso médio por animal por dia (0,629 e 0,511 kg dia -1 ) e por hectare (886 e 674 kg ha -1 ), bem como de taxa de lotação (3,13 e 2,85 UA ha -1 ), foram observados nos pastos manejados com altura pré-pastejo de 25 cm. A aplicação de 200 kg ha -1 de N resultou em aumentos na percentagem de folhas na massa de forragem pós-pastejo, nas taxas de acúmulo de forragem, na taxa de lotação e no ganho de peso por área. A mais adequada estratégia de manejo corresponde à altura pré-pastejo de 25 cm, independentemente da dose de nitrogênio utilizada.Termos para indexação: Urochloa brizantha, altura do dossel, altura pré-pastejo, altura pós-pastejo, manejo do pastejo, taxa de lotação. Weight gain and animal productivity on Marandu palisade grass under rotational stocking and nitrogen fertilizationAbstract -The objective of this work was to assess management targets for marandu palisade grass (Urochloa brizantha cv. Marandu) subjected to rotational stocking and to nitrogen fertilization rates, from January 2009 to April 2010. Treatments consisted of a combination of two grazing frequencies (pre-grazing heights of 25 and 35 cm) and two levels of nitrogen application (50 and 200 kg ha -1 per year). in a completely randomized block design, in a 2x2 factorial arrangement, with four replicates. The established post-grazing height was 15 cm. Greater values of daily weight gain per animal per day (0.629 and 0.511 kg day -1 ), weight gain per hectare (886 and 674 kg ha -1 ), and stocking rate (3.13 and 2.85 AU ha -1 ) were found for pre-grazing height of 25 cm. The application of 200 kg ha -1 of N increased the percentage of leaves in post-grazing forage mass, forage accumulation rate, stocking rate, as well as weight gain per hectare. The best grazing strategy corresponds to the pre-grazing height of 25 cm, regardless of the nitrogen application.

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Enteric methane (CH 4 ) production attributable to beef cattle contributes to global greenhouse gas emissions. Reliably estimating this contribution requires extensive CH 4 emission data from beef cattle under different management conditions worldwide. The objectives were to: 1) predict CH 4 production (g d −1 animal −1 ), yield [g (kg dry matter intake; DMI)−1 ] and intensity [g (kg average daily gain) −1 ] using an intercontinental database (data from Europe, North America, Brazil, Australia and South Korea); 2) assess the impact of geographic region, and of higher-and lower-forage diets. Linear models were developed by incrementally adding covariates. A K-fold cross-validation indicated that a CH 4 production equation using only DMI that was fitted to all available data had a root mean square prediction error (RMSPE; % of observed mean) of 31.2%. Subsets containing data with

The present study was conducted to evaluate the effect of lipids with different fatty acid profiles on the intake, performance, and enteric CH4 emission of Nellore steers. A total of 45 Nellore animals with an average initial BW of 419 ± 11 kg (at 15 ± 2 mo) were distributed in a completely randomized design consisting of 5 treatments and 9 replicates. The roughage feed was maize silage (600 g/kg on a DM basis) plus concentrate (400 g/kg on a DM basis). The dietary treatments were as follows: without additional fat (WF), palm oil (PO), linseed oil (LO), protected fat (PF; Lactoplus), and whole soybeans (WS). The lipid source significantly affected (P < 0.05) nutrient intake. The greatest intakes of DM, OM, and CP were observed in the animals that were fed the WF or PF diets, and the lowest intakes were observed in the animals that were fed the PO diet. Intake of NDF decreased (P < 0.05) with the addition of PO. Enteric methane emission (g/kg DMI) was reduced by an average of 30% when the animals were fed diets containing WS, LO, and PO (P < 0.05), and these diets caused a larger reduction in the energy loss in the form of methane compared to those without added fat and with added PF (3.3 vs. 4.7%). The different fatty acid profiles did not affect the backfat thickness or the loin eye area of the animals (P > 0.05). However, animals fed PO displayed lower daily weight gain (0.36 kg/d), feed efficiency (0.08 kg ADG/kg DM), HCW (245 kg), and hot yield percentage (52.6%) compared to animals that were fed the other diets. Therefore, PO compared to the other lipid sources used in this study reduces intake, performance, feed efficiency, and carcass yield. Therefore, PO is not suggested for feedlot-finished animals.

This study investigated the long-term effects (13 months) of encapsulated nitrate supplementation (ENS) on enteric methane emissions, rumen fermentation parameters, ruminal bacteria, and diversity of archaea in grazing beef cattle. We used a total of thirty-two Nellore steers (initial BW of 197 ± 15.3 kg), 12 of which were fitted with rumen cannulas. For 13 months, the animals were maintained in 12 paddocks and fed a concentrate of ground corn, soybean meals, mineral supplements, and urea (URS) or encapsulated nitrate (EN) containing 70 g of EN/100 kg of BW (corresponding to 47 g NO 3 - /100 kg BW). Encapsulated nitrate supplementation resulted in similar forage, supplement and total DMI values as URS ( P > 0.05), but ENS tended to increase (+48 g/d; P = 0.055) average daily weight gain. Daily reductions in methane emissions (-9.54 g or 18.5%) were observed with ENS when expressed as g of CH 4 /kg of forage dry matter intake (fDMI) ( P = 0.037). Lower concentrations of NH 3 -N and a higher ruminal pH were observed in ENS groups 6 h after supplementation ( P < 0.05). Total VFA rumen concentration 6 h ( P = 0.009) and 12 h after supplementation with EN resulted in lower acetate concentrations in the rumen ( P = 0.041). Steers supplemented with EN had a greater ruminal abundance of Bacteroides, Barnesiella, Lactobacillus , Selenomonas, Veillonella, Succinimonas, Succinivibrio , and Duganella sp. ( P < 0.05), but a lower abundance of Methanobrevibacter sp. ( P = 0.007). Strong negative correlations were found between daily methane emissions and Proteobacteria, Erysipelotrichaceae, Prevotellaceae, and Roseburia , Kandleria , Selenomonas , Veillonella , and Succinivibrio sp. ( P < 0.05) in the rumen of ENS steers. Encapsulated nitrate is a feed additive that persistently affects enteric methane emission in grazing steers, thereby decreasing Methanobrevibacter abundance in the rumen. In addition, ENS can promote fumarate-reducer and lactate-producer bacteria, thereby reducing acetate production during rumen fermentation.