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-The objective of this work was to evaluate three tropical forage species for their in vitro methane (CH 4 ) production and organic matter degradability, in order to determine the relationships between forage grass nutritive quality and CH 4 production. Guinea grass (Megathyrsus maximus), palisade grass (Urochloa brizantha), and signal grass (Urochloa decumbens) were evaluated. Palisade grass showed the highest organic matter, neutral detergent fiber, acid detergent fiber, lignin, and lower-crude protein content. Signal grass had the highest values for hemicellulose and neutral detergent fiber-nitrogen, and the lowest-cellulose content. Guinea grass and signal grass showed a higher-total gas production than palisade grass. Besides, Guinea grass showed an increased CH 4 production, and palisade grass showed lower value for truly degraded organic matter, and reduced partitioning factor, in comparison to signal grass. An increased CH 4 production was observed in cases of lower hemicellulose and paratitioning factor. The nutritive value and CH 4 production of forages may be employed as parameters, aiming at the sustainability of ruminant production.Index terms: Brachiaria, Megathyrsus maximus, Urochloa, livestock, methane production. Características morfológicas, qualidade nutritiva e produção de metano de gramíneas tropicais no BrasilResumo -O objetivo deste trabalho foi avaliar três espécies de gramíneas tropicais quanto à produção de metano (CH 4 ) in vitro e à degradabilidade da matéria orgânica, para determinar as relações entre a qualidade nutritiva das gramíneas e a produção de CH 4 . O capim-colonião (Megathyrsus maximus), o capim-braquiarão (Urochloa brizantha) e o capim-decumbens (Urochloa decumbens) foram avaliados. O capim-braquiarão apresentou os maiores teores de matéria orgânica, fibra em detergente neutro, fibra em detergente ácido e lignina, e o menor teor de proteína bruta. O capim-decumbens apresentou os maiores teores de hemicelulose e de nitrogênio em fibra de detergente neutro, além do menor teor de celulose. O capim-colonião e o capimdecumbens apresentaram maior produção total de gases do que o braquiarão. Além disso, o capim-colonião apresentou maior produção de CH 4 , e o capim-braquiarão, menor degradabilidade verdadeira da matéria orgânica e reduzido fator de partição, em comparação ao capim-decumbens. Maior produção de CH 4 foi verificada em casos em que os valores de hemicelulose e fator de partição foram menores. A qualidade nutricional e a produção de CH 4 das forragens avaliadas podem ser utilizadas como parâmetros a serem empregados, que visem a sustentabilidade da produção de ruminantes.Termos para indexação: Brachiaria, Megathyrsus maximus, Urochloa, pecuária, produção de metano.

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Context Sorghum (Sorghum bicolor (L.) Moench) grain with low tannin content may be suitable as an alternative to maize (Zea mays L.) grain in ruminant diets in terms of input costs and drought tolerance, and effects on growth performance and mitigation of methane (CH4) emissions. Aims The study aimed to evaluate the effects of substitution of maize with sorghum grain at different rates on ruminal microbial protein synthesis, CH4 formation and liveweight gain in growing ruminants. Methods Twenty-five Santa Inês lambs (bodyweight 19.0 ± 1.5 kg) were randomly divided into five dietary treatments. Control diet components (on a dry matter basis) were Tifton-85 hay (400 g/kg), maize (405 g/kg), soybean meal (165 g/kg) and commercial mineral supplement (30 g/kg). Sorghum diets comprised the basal diet with the maize grain proportionately substituted with sorghum grain at 25%, 50%, 75% and 100% (diets S25–S100). Lamb feed intake, growth performance, nutrient digestibility, nitrogen balance, microbial protein synthesis and CH4 emission were measured during an experimental period of 70 days. Key results Negligible variations of chemical composition were observed among the experimental diets, although numerical increases in condensed tannins were observed with increasing levels of sorghum replacement. There was no significant effect of level of sorghum inclusion on feed intake. Partial substitution of maize with sorghum grain increased lamb average daily gain linearly (P = 0.02) and quadratically (P = 0.002) compared with diets based on either grain alone, with the S50 lambs having the highest values. A linear decrease in dry matter digestibility (P = 0.02), organic matter (P = 0.02) and acid detergent fibre (P = 0.002) was observed for lambs receiving sorghum diets compared with the control. A significant linear (P = 0.023) effect was observed for retained nitrogen (g/day), with lambs fed S25 and S50 having higher values than those in other treatments. All partially substituted diets (S25, S50 and S75) reduced CH4 per unit bodyweight gain in a linear trend (P = 0.03), by 35%, 29% and 33%, respectively, and tended to increase (linear effect, P = 0.09) the calculated amounts of absorbed microbial protein compared with the control diet. Conclusions Low tannin sorghum grains can replace maize grains by up to 75% to maximise ruminal microbial biomass production for optimal lamb growth performance and reduced CH4 emission. Implications Animal productivity can be enhanced while mitigating the environmental impact of livestock production through the partial substitution of maize by low tannin sorghum grains in ruminant diets.

Several previous studies on targeted food items using carbon and nitrogen stable isotope ratios in Brazil have revealed that many of the items investigated are adulterated; mislabeled or even fraud. Here, we present the first Brazilian isotopic baseline assessment that can be used not only in future forensic cases involving food authenticity, but also in human forensic anthropology studies. The δ13C and δ15N were determined in 1245 food items and 374 beverages; most of them made in Brazil. The average δ13C and δ15N of C3 plants were −26.7 ± 1.5‰, and 3.9 ± 3.9‰, respectively, while the average δ13C and δ15N of C4 plants were −11.5 ± 0.8‰ and 4.6 ± 2.6‰, respectively. The δ13C and δ15N of plant-based processed foods were −21.8 ± 4.8‰ and 3.9 ± 2.7‰, respectively. The average δ13C and δ15N of meat, including beef, poultry, pork and lamb were -16.6 ± 4.7‰, and 5.2 ± 2.6‰, respectively, while the δ13C and δ15N of animal-based processed foods were −17.9 ± 3.3‰ and 3.3 ± 3.5‰, respectively. The average δ13C of beverages, including beer and wine was −22.5 ± 3.1‰. We verified that C-C4 constitutes a large proportion of fresh meat, dairy products, as well as animal and plant-based processed foods. The reasons behind this high proportion will be addressed in this study.