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Complex cross-talk occurs between gastrointestinal nematodes and gut symbiotic microbiota, with consequences for animal metabolism. To investigate the connection between methane production and endoparasites, this study evaluated the effect of mixed infection with Haemonchus contortus and Trichostrongylus colubriformis on methanogenic and methanotrophic community in rumen microbiota of lambs using shotgun metagenomic and real-time quantitative PCR (qPCR). The rumen content was collected from six Santa Inês lambs, (7 months old) before and after 42 days infection by esophageal tube. The metagenomic analysis showed that the infection affected the microbial community structure leading to decreased abundance of methanotrophs bacteria, i.e. α-proteobacteria and ß-proteobacteria, anaerobic methanotrophic archaea (ANME), protozoa, sulfate-reducing bacteria, syntrophic bacteria with methanogens, geobacter, and genes related to pyruvate, fatty acid, nitrogen, and sulfur metabolisms, ribulose monophosphate cycle, and Entner-Doudoroff Pathway. Additionally, the abundance of methanogenic archaea and the mcrA gene did not change. The co-occurrence networks enabled us to identify the interactions between each taxon in microbial communities and to determine the reshaping of rumen microbiome associations by gastrointestinal nematode infection. Besides, the correlation between ANMEs was lower in the animal's postinfection. Our findings suggest that gastrointestinal parasites potentially lead to decreased methanotrophic metabolism-related microorganisms and genes.

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Climate change is a very relevant and worrying topic today and is present in the agendas of different spheres of society. High concentrations of greenhouse gases (GHGs) are released into the atmosphere, causing global temperatures to rise. In agricultural production, methane (CH4) is considered one of the highest GHG emissions, causing a negative impact on natural resources and accelerating climate change. In the coming years, with the increase in the world population, food production should be implemented in self-sufficient, quality, and sustainable production systems to meet the need for high consumption. The reduction in CH4 production is related to the better efficiency of energy use of the feed by the animals; therefore, the knowledge of the ruminal fermentation parameters, identification of the ruminal microbiota, and selection of more efficient animals, with lower consumption and greater weight gain, in addition to producing less GHGs like CH4, have a less negative impact on the environment and are economically viable. This review presents some aspects of selection for feed efficiency in sheep as a strategy to mitigate GHG emission and some techniques for measuring these gases.

As alterações climáticas são tema muito relevante e preocupante na atualidade e está presente nas pautas de diferentes esferas da sociedade. Altas concentrações de gases de efeito estufa são lançados na atmosfera, fazendo com que a tem-peratura global se eleve. Na produção agrícola, o metano (CH4) é considerado uma das maiores emissões de GEE, causando impacto negativo nos recursos naturais e acelerando as mudanças climáticas. Nos próximos anos, com o aumento da população mundial, a produção de alimentos deverá estar implementada em sistemas produtivos autossuficientes, de qualidade e sustentáveis para suprir a necessidade do elevado consumo. A redução na produção de CH4 está relacionada com a melhor eficiência do uso de energia da ração pelos animais; portanto, o conhecimento dos parâmetros da fermentação ruminal, identificação da microbiota ruminal e seleção de animais mais eficientes, com menor consumo e maior ganho de peso, além de produzirem menos GEEs como o CH4, impactam menos o meio ambiente e são economicamente viável. Esta revisão apresenta alguns aspectos da seleção para eficiência alimentar em ovinos como estratégia para mitigar a emissão de GEE e algumas técnicas para mensuração desses gases

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This study assessed the association between encapsulated nitrate product (ENP) and monensin (MON) to mitigate enteric methane (CH4) in vitro and possible effects on ruminal degradability, enteric fermentation characteristics, and microbial populations. Six treatments were used in randomized complete design in a 2×3 factorial arrangement with two levels of MON (0 and 2.08 mg/mL of buffered rumen fluid) and three levels of ENP (0, 1.5 and 3.0%). The substrate consisted of 50% Tifton-85 hay and 50% concentrate mixture (ground corn and soybean meal). ENP replaced soybean meal to achieve isonitrogenous diets (15% CP). No ENP×MON interaction was observed for any measured variable (P > 0.05) except for the relative abundance of F. succinogenes (P = 0.02) that linearly increased in diets with MON when ENP was added. The ENP addition decreased CH4 production (P < 0.01) without affecting (P > 0.05) truly degraded organic matter nor the relative abundance of methanogens. Hydrogen production was reduced with MON (P = 0.04) and linearly decreased with ENP inclusion (P = 0.02). We concluded that use of nitrate is a viable strategy for CH4 reduction, however, no additive effect of ENP and MON was observed for mitigating CH4 production.

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The importance of beef production for economy of Brazil and the growing demand for animal protein across the globe warrant an improvement in the beef production system. Although most attention has been on modulation of the rumen microbiome to improve ruminant production, the role of the lower gut microbiome in host health and nutrition remains relatively unexplored. This work aimed to investigate the taxonomy and functional variations in the fecal microbiome of Brazilian beef cattle reared in two different production systems using a metagenomic approach. Sixty male beef cattle from six farms representing semi-intensive (I, n = 2) and traditional (T, n = 4) Brazilian beef production systems were enrolled in the study. Shotgun sequencing was used to characterize taxonomic and functional composition and diversity of the microbiome in fecal samples collected from each animal. Fecal samples were analyzed for copper (Cu), lead (Pb), nitrogen (N), phosphorous (P), selenium (Se), and zinc (Zn) and stable isotopes of carbon (13C) and nitrogen (15N). The fecal microbiome was influenced by the beef production systems with greater functional and lower taxonomic diversity in beef cattle feces from I systems compared with that from T systems. The concentration of N, P, and Zn was higher in beef cattle feces from I systems compared with that from T systems and was associated with taxonomic and functional profile of fecal microbiome in I system, suggesting the role of fecal nutrients in shaping system-specific microbiome. Semi-intensive management practices led to a more complex but less connected fecal microbiome in beef cattle. The microbial community in beef cattle feces from I systems was characterized by greater abundance of beneficial bacteria (phylum Firmicutes and butyrate-producing bacteria family Lachnospiraceae and genera Anaerostipes, Blautia, Butyrivibrio, Eubacterium, Roseburia, and Ruminococcus). In addition, the fecal abundance of microbial genes related to immune system, nutrient metabolism, and energy production was greater in beef cattle raised under I systems compared with that under T systems. Findings of the current study suggest that semi-intensive management practices could facilitate the development of a healthier and more efficient fecal microbiome in beef cattle by driving an increase in the abundance of beneficial bacteria and functional genes.

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A total of 40 lambs were divided into four different treatments according to the inclusion level of the macadamia nut cake: C-control (0%), M1 (6.5%), M2 (12%) and M3 (20%). Feed was provided twice a day; animal weighing along with body condition scoring occurred within a 14-day interval. The lambs were slaughtered at the end of the performance test. Analysis of variance was performed through the Mixed procedure of the SAS, as well as linear and quadratic regression analysis. The groups presented differences between the treatments (P <0.05) for dry matter intake (DMI), ethereal extract intake (EEI), consumption in relation to live weight percentage and feed conversion ratio (FCR). The lowest mean DMI was obtained by the animals that received the M2 and differed from the C treatment, whose average was the highest. The EEI was highest for the M3 group and the FCR was also better for this group. There was a linear effect for EEI and FCR, and quadratic for crude protein intake. There was no effect for carcass characteristics, and only initial pH had a decreasing linear effect. The macadamia nut cake was effective in promoting the performance of the animals, since there was an improvement in feed conversion.

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Free gossypol is a toxic compound which naturally occurs in cottonseed and its derivates, affecting animal and possibly human health. Consequently, alternatives for gossypol destruction must be evaluated. This work evaluated the emerging technology of ozone processing for free gossypol destruction in cottonseed meal. Ozonation was carried out in the actual cottonseed meal and also a model system, designed to describe the involved mode of action. The model system consisted of glass pearls beads covered with free gossypol. Ozonation was performed in two ways: as a static process, i.e., without homogenising the sample after placing them in the reactor, and also homogenising it. Ozone degraded free gossypol in all the systems, but reaching different levels. Free gossypol reduction was higher in the model system than the cottonseed meal, and higher in the homogenised processing than the static one: cottonseed meal in homogenised (56%) and static (25%); model system homogenised (98%) and static (80%). The obtained differences suggest a problem of gas penetration in the solid particles, the effect of unexposed surfaces due to contact areas, and the reaction with other organic molecules further than the target. Ozonation is a promising technique for gossypol degradation in cottonseed meal, but additional strategies are needed to optimise the ozonation process and evaluate toxicological aspects.

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Cassava (Manihot esculenta Crantz) bagasse is the by-product from industry (BCI), generated during manufacturing of cassava flour; this material has significant amounts of carbohydrates consisting in a potential energy source for ruminants. We hypothesized that the inclusion of BCI in the diets may lead to fermentation parameters equivalent to those of conventional feedstuff such as tropical grasses or grains; therefore, we aimed to evaluate ruminal fermentation parameters of BCI in in vitro conditions. Three different substrates were prepared: 100% BCI (BCI diet), 100% tifton (Cynodon spp.) hay (CTL diet), and 50% tifton hay +50% BCI (THB diet). Ruminal fermentation parameters of these diets were evaluated in in vitro gas production assays. In a 24-h incubation, increased values for total gas production, organic matter degradability, and methane production were observed for BCId and THB as compared to CTL (p < 0.05), while neutral THB showed the highest value for neutral detergent fiber degradability (p < 0.05). Fermentation profile was evaluated in a 48-h assay: shorter lag time as well as increased gas production potential and fractional fermentation rate were observed for the BCId and THB as compared to CTL (p < 0.05). Our results suggested that by-product from cassava industry is a suitable feed for ruminant production, providing desirable in vitro ruminal fermentation performance and organic matter degradability.

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The objective of this study was to evaluate the grazing of goats in a grass monoculture system and in intercropping systems of grass + legumes. A randomized block design was adopted, with the treatments arranged in a split-plots scheme. The plots consisted of three cropping systems: monoculture-Andropogon gayanus cv. Planaltina; mixture I-A. gayanus cv. Planaltina + Stylosanthes cv. Campo Grande; and mixture II-A. gayanus cv. Planaltina + Calopogonium mucunoides. The subplots consisted of two grazing cycles. The highest (P = 0.04) total forage mass (TFM) was recorded in the mixture I (A. gayanus cv. Planaltina + Stylosanthes. cv. Campo Grande), which was 2.6 ± 0.1 tons DM/ha. The crude protein (CP) was lower in the monoculture which also showed the highest content of neutral detergent fiber (NDF). The grazing time in the monoculture was the longest (8.23 ± 1.14 h). The goats used a longer time for rumination (P < 0.01) in the mixture I. The lowest (P < 0.01) bite rate was found in mixture II in comparison to the other cropping systems. The bite rate was higher (P < 0.01) in grazing cycle II than in all the other cropping systems. In mixture I, the Stylosanthes cv. Campo Grande, and in mixture II, the C. mucunoides presented the lowest (P < 0.01) δ13C value in the forage. The highest forage intake occurred in the mixture systems (P < 0.01) in comparison to the monoculture. The mixture pastures presented better results for forage mass, nutritive value, and intake in comparison to the monoculture.

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During specific times of the year, especially dry seasons, tropical forages typically have poor nutritional value due to high contents of neutral and acid detergent fibres, and low crude protein in their composition, which may reduce productivity of ruminant livestock production and lead to increased enteric methane (CH4 ) emissions per unit of generated product in forage-bases systems. In order to increase fibre degradability and the efficiency of energy utilisation from low-quality forages, exogenous fibrolytic enzymes have been studied. In this assay, we evaluated the effects of increasing dose levels of fibrolytic enzymes extract (FEE) produced by Trichoderma reesei on in vitro rumen organic matter degradability, fermentation parameters, total gas and CH4 production of tropical forages. Forage samples were analysed for their bromatological composition, and enzyme activity from FEE was performed for xylanase and endoglucanase. The in vitro gas production technique was used in a 5 × 3 factorial arrangement with five FEE dose levels (0, 5, 50, 500 and 5,000 µl) and three substrates (Cynodon spp., Panicum maximum and Cenchrus ciliaris L.). The highest dose level of FEE increased degradability, total gas and CH4 production in all substrates (p < .05). Butyrate concentration also increased while acetate:propionate ratio and pH decreased with the addition of FEE (p < .05). These results indicated that the use of fibrolytic enzymes can be a reliable strategy to improve degradability of low-quality forages, contributing to the sustainability and intensification of livestock production in tropical countries.

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This study aimed to evaluate the effects of Trichostrongylus colubriformis infection on the hemato-biochemical parameters, feed digestibility, and nitrogen balance in Santa Inês lambs. Eighteen three-month-old Santa Ines castrated male lambs (16.9 ± 1.43 kg of body weight) were randomly distributed in two experimental treatments: infected with T. colubriformis (I, n = 9) and uninfected (U, n = 9). The I group received a total of 45,000 L3 larvae of T. colubriformis (5,000 infective larvae, three times per week, for three weeks). During the experimental period, blood, feed digestibility, and nitrogen balance were evaluated. The I lambs showed a reduction in erythrocytes, hemoglobin, hematocrit, mean corpuscular volume, and total proteins, as well as an increase in platelets and eosinophils compared to those in the U group (p < 0.05). With the exception of total protein content, these values were within the normal range for the species. Furthermore, lower dry matter and organic matter digestibility were observed in the I lambs (p = 0.08). The present findings highlight that T. colubriformis infection has the potential to impair some hemato-biochemical parameters as well as feed digestibility in lambs, which could affect their productivity.

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This study was carried out to evaluate the effects of tannin supplementation on ruminal microbiota of sixteen lambs infected and non-infected with Haemonchus contortus and Trichostrongylus colubriformis. Animals were fed with hay, concentrate and supplemented with Acacia mearnsii (A. mearnsii). The animals were divided into four treatments: two control groups without infection, either receiving A. mearnsii (C+) or not (C-), and two infected groups, one with A. mearnsii (I+) and another without A. mearnsii (I-). Ruminal short-chain fatty acids (SCFA) and metagenome sequencing of ruminal microbiota were used to evaluate the effect of tannin and infection on ruminal microbiome. For SCFA, differences were observed only with A. mearnsii. Total SCFA and acetate molar percentage were decreased in C+ and I+ (P<0.05). Butyrate, valerate and isovalerate were higher in lambs that received A. mearnsii in the diet (P<0.05). The infection changed the microbiome structure and decreased the abundance of butyrate-producing microorganisms. In addition, A. mearnsii supplementation also affected the structure the microbial community, increasing the diversity and abundance of the butyrate-producing and probiotics bacteria, amino acid metabolic pathways, purine, pyrimidine and sphingolipid metabolism. Together, our findings indicate that A. mearnsii supplementation modulates important groups related to nitrogen, amino acid, purine and pyrimidine metabolism, in rumen microbiome, affected by gastrointestinal nematodes infection in lambs.

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Chromium (Cr) is a micromineral that is involved in the metabolism of carbohydrates, lipids, ammonia, and nucleic acids; thus, its supplementation can influence the nutritional status of ruminants, and consequently, colostrum profile, since this secretion depends on products secreted by the mammary gland and elements of the maternal bloodstream. The present study investigated the influence of supplementation with Cr bound to organic molecule on the nutritional, immune, and antioxidant quality of ewe colostrum. Thirty-two multiparous Santa Ines ewes (55.3 ± 8.00 kg body weight) were randomly assigned into four groups: T1 (0.0 mg of chromium picolinate (CrPic) supplementation per ewe, n = 8), T2 (0.15 mg of CrPic per ewe, n = 9), T3 (0.30 mg of CrPic per ewe, n = 7), and T4 (0.45 mg of CrPic per ewe, n = 8). Supplementation was supplied during the breeding season, pregnancy, and lactation. Shortly after calving, the first milking colostrum was collected to determine its chemical composition, activity of lysozyme, lactoperoxidase, ceruloplasmin, catalase, glutathione peroxidase, and oxygen radical absorbance capacity. The results show that lactoperoxidase activity decreased with CrPic supplementation (P < 0.01), revealing that this micromineral reduces an important component of defense mechanism in the body. Therefore, the results of this work show that supplementation with chromium picolinate influences colostrum quality.

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Urea coated with copper and boron may be a vehicle for selenium fertilization in grazing systems to improve both forage and animal productivity, and consequently, the nutritional quality of milk and meat. Urea is the most often used form of N fertilizer in Brazil; however, it can experience high losses by volatilization, primarily in pastures with high amounts of senescent biomass. The goal of this study was to evaluate losses by ammonia volatilization from urea coated with Cu, B, and Se. The fertilizer was applied to the soil surface under forage straw residues in cylindric glass chambers under controlled laboratory conditions. The treatments were urea (UR), urea coated with boric acid and copper sulfate (UBC), urea coated with boric acid, copper sulfate, and selenium (UBCS), and ammonium sulfate (AS). Measurements were recorded at regular intervals after fertilizer application for 27 days. High losses occurred from ammonia volatilization of amidic-N sources in the initial days after fertilizer application. The total loss of N by ammonia volatilization according to fertilizer treatment was UR > UBC = UBCS > AS. Urea lost by ammonia volatilization accounted for up to 50% of the N applied, although losses from coated urea treatments UBC and UBCS were 11.45% lower than that of urea. The Cu and B in the coated urea reduced losses by ammonia volatilization and the inclusion of Se had no effect. It is suggested that Se may be added to the Cu and B coating of urea to reduce ammonia volatilization.(AU)

O revestimento de ureia com Cu e B pode ser um veículo para a adubação com selênio (Se) em pastagens melhorando a produtividade da forragem e animal e, consequentemente a qualidade nutricional de leite e carne. A ureia é a fonte de N mais utilizada no Brasil, porém pode apresentar elevadas perdas por volatilização, principalmente em pastagens com altas quantidades de biomassa senescente. O objetivo foi avaliar as perdas por volatilização de amônia em ureia revestida com Cu, B e Se aplicado em superfície sob resíduos de palhada de forragem em câmaras cilíndricas de vidro sob condições controladas em laboratório. Os tratamentos foram ureia revestida com ácido bórico e sulfato de cobre (UBC), ureia revestida ácido bórico, sulfato de cobre e selênio (UBCS), e sulfato de amônio (AS) e medidas nos dias após aplicação dos fertilizantes. Altas perdas por volatilização de amônia a partir das fontes amídicas ocorreram nos primeiros dias após a aplicação dos fertilizantes. As perdas totais de N por volatilização de amônia comparando os fertilizantes foi de UR>UBC=UBCS>AS. A ureia perdeu amônia por volatilização em até 50% do N aplicado, enquanto as perdas com as ureias revestidas UBC e UBCS foram 11,45% menores que a ureia. O Cu e o B no revestimento da ureia reduzem as perdas por volatilização de amônia e a inclusão do Se não apresenta influência.(AU)

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This study aimed to evaluate the effects of Trichostrongylus colubriformis infection on the hemato-biochemical parameters, feed digestibility, and nitrogen balance in Santa Inês lambs. Eighteen three-month-old Santa Ines castrated male lambs (16.9 ± 1.43 kg of body weight) were randomly distributed in two experimental treatments: infected with T. colubriformis (I, n = 9) and uninfected (U, n = 9). The I group received a total of 45,000 L3 larvae of T. colubriformis (5,000 infective larvae, three times per week, for three weeks). During the experimental period, blood, feed digestibility, and nitrogen balance were evaluated. The I lambs showed a reduction in erythrocytes, hemoglobin, hematocrit, mean corpuscular volume, and total proteins, as well as an increase in platelets and eosinophils compared to those in the U group (p < 0.05). With the exception of total protein content, these values were within the normal range for the species. Furthermore, lower dry matter and organic matter digestibility were observed in the I lambs (p = 0.08). The present findings highlight that T. colubriformis infection has the potential to impair some hemato-biochemical parameters as well as feed digestibility in lambs, which could affect their productivity.(AU)

O objetivo deste estudo foi avaliar os efeitos da infecção por Trichostrongylus colubriformis nos parâmetros hemato-bioquímicos, digestibilidade aparente dos nutrientes e balanço de nitrogênio de cordeiros Santa Inês. Dezoito cordeiros Santa Inês, de três meses de idade e castrados (16,9 ± 1,43 kg de peso corporal), foram distribuídos aleatoriamente em dois tratamentos experimentais: infectados com T. colubriformis (I, n = 9) e não infectados (U, n = 9). O grupo I recebeu um total de 45.000 larvas L3 de T. colubriformis (5.000 larvas infectantes, três vezes por semana, durante três semanas). Durante o período experimental, foram avaliadas as variáveis sanguíneas, digestibilidade e balanço de nitrogênio. Os cordeiros I apresentaram redução de eritrócitos, hemoglobina, hematócrito, volume corpuscular médio e proteínas totais, além de aumento de plaquetas e eosinófilos, quando comparados ao grupo U (p< 0,05). Contudo, exceto para proteínas totais, os valores estavam dentro do intervalo normal para a espécie. Além disso, a digestibilidade da matéria seca e da matéria orgânica foi menor no grupo I de cordeiros (p = 0,08). Os presentes achados destacam que a infecção por T. colubriformis teve potencial para prejudicar alguns parâmetros hemato-bioquímicos, bem como a digestibilidade aparente da dieta, o que poderia afetar a produtividade dos cordeiros.(AU)

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Gossypol easily pairs with lysine side chains and enzymes involved in the cellular growth process. The effect of gossypol (a compound present in cotton co-products) in ruminant metabolism and meat quality is not yet clear. This study was undertaken in order to evaluate the effects of cotton co-products in lamb muscle proteome. Twenty-four Santa Inês ram lambs, 5-months old (20.6 ± 1.9 kg), were randomly assigned to four treatments: control (without cottonseed), whole cottonseed, cottonseed meal and high oil cottonseed meal. At 95 days into the experiment, lambs were slaughtered and samples from Longissimus dorsi were collected. Proteins were extracted and analyzed by 2-D electrophoresis. Spots showing a significant effect from the treatment (the “treatment effect”) and present in more than 90 % of the samples were identified using mass spectrometry. Cotton co-products decreased the abundance of aldehyde and malate dehydrogenases, creatine kinase M-type and Adenosine triphosphate (ATP) synthase. They also increased four proteins related to muscle contraction. Thus, feeding cotton co-products to lambs changed the abundance of important muscle proteins. A cotton co-product diet induced a negative impact on the energy supply of muscle cells and, consequently, the abundance of ATP dependent proteins (contractile apparatus) increased, probably in order to offset and maintain muscle function. These proteomic changes can promote our understanding of alterations in the sensorial properties of meat due to cotton co-product diets in further investigations.(AU)

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Crude glycerol is a major by-product of biodiesel production and is an economical additive feed for ruminants. However, residual methanol in crude glycerol can be harmful to animal health. Several methods exist for quantifying methanol residues in biodiesel, yet few have been described that identify the methanol level in crude glycerol. We propose a method for determining the methanol level in crude glycerol destined for animal feed. Crude glycerol was extracted from the headspace and quantified by gas chromatography using a flame ionization detector (GC-FID). The method was linear up to 0.5 % of methanol. The limits of detection (LOD) and quantification (LOQ) were 0.015 and 0.031 %, respectively. No significant matrix effects were observed. Precision was 2 % at the 0.05 and 0.5 % levels. The average percentage of recovery was 90 %. Three analyzed samples of crude glycerol had methanol residues of 0.027-7.802 %. Furthermore, this methanol quantification method may be externally or internally calibrated using a GC manual injector. A reduction of at least 20 % in running time was obtained with good resolution between the peaks. Thus, this method can be applied to determine the methanol level in crude glycerol according to the upper limits for animal feed (5,000 ppm) and for human consumption (150 ppm). Finally, this method is useful for the quality control of crude glycerol intended for use in animal feed, enabling the alternative use of this by-product to add value to the biodiesel production chain.(AU)

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Crude glycerol is a major by-product of biodiesel production and is an economical additive feed for ruminants. However, residual methanol in crude glycerol can be harmful to animal health. Several methods exist for quantifying methanol residues in biodiesel, yet few have been described that identify the methanol level in crude glycerol. We propose a method for determining the methanol level in crude glycerol destined for animal feed. Crude glycerol was extracted from the headspace and quantified by gas chromatography using a flame ionization detector (GC-FID). The method was linear up to 0.5 % of methanol. The limits of detection (LOD) and quantification (LOQ) were 0.015 and 0.031 %, respectively. No significant matrix effects were observed. Precision was 2 % at the 0.05 and 0.5 % levels. The average percentage of recovery was 90 %. Three analyzed samples of crude glycerol had methanol residues of 0.027-7.802 %. Furthermore, this methanol quantification method may be externally or internally calibrated using a GC manual injector. A reduction of at least 20 % in running time was obtained with good resolution between the peaks. Thus, this method can be applied to determine the methanol level in crude glycerol according to the upper limits for animal feed (5,000 ppm) and for human consumption (150 ppm). Finally, this method is useful for the quality control of crude glycerol intended for use in animal feed, enabling the alternative use of this by-product to add value to the biodiesel production chain.

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Gossypol easily pairs with lysine side chains and enzymes involved in the cellular growth process. The effect of gossypol (a compound present in cotton co-products) in ruminant metabolism and meat quality is not yet clear. This study was undertaken in order to evaluate the effects of cotton co-products in lamb muscle proteome. Twenty-four Santa Inês ram lambs, 5-months old (20.6 ± 1.9 kg), were randomly assigned to four treatments: control (without cottonseed), whole cottonseed, cottonseed meal and high oil cottonseed meal. At 95 days into the experiment, lambs were slaughtered and samples from Longissimus dorsi were collected. Proteins were extracted and analyzed by 2-D electrophoresis. Spots showing a significant effect from the treatment (the “treatment effect”) and present in more than 90 % of the samples were identified using mass spectrometry. Cotton co-products decreased the abundance of aldehyde and malate dehydrogenases, creatine kinase M-type and Adenosine triphosphate (ATP) synthase. They also increased four proteins related to muscle contraction. Thus, feeding cotton co-products to lambs changed the abundance of important muscle proteins. A cotton co-product diet induced a negative impact on the energy supply of muscle cells and, consequently, the abundance of ATP dependent proteins (contractile apparatus) increased, probably in order to offset and maintain muscle function. These proteomic changes can promote our understanding of alterations in the sensorial properties of meat due to cotton co-product diets in further investigations.

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The objective of this study was to evaluate the effects of using encapsulated nitrate product (ENP) replacing soybean meal in diets differing in concentrate to forage ratio on ruminal fermentation and methane production in vitro using a semi-automatic gas production technique. Eight treatments were used in a randomized complete design with a 2 × 4 factorial arrangement: two diet (20C:80F and 80C:20F concentrate to forage ratio) and four levels of ENP addition (0%, 1.5%, 3.0%, and 4.5% of DM) replacing soybean meal. There was a diet × ENP interaction (p = 0.02) for methane production. According to ENP addition, diets with 80C:20F showed more intense reduction on methane production that 20C:80F. A negative linear effect was observed for propionate production with ENP addition in diet with 80C:20F and to the relative abundance of methanogens Archaea, in both diet. The replacement of soybean meal by ENP in levels up to 3% of DM inhibited methane production due to a reduction in the methanogens community without affecting the organic matter degradability. However, ENP at 4.5% of DM level affected fiber degradability, abundance of cellulolytic bacteria, and propionic acid production, indicating that this level of inclusion is not recommended for ruminant production.

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BACKGROUND: Brazil has the largest commercial herd of ruminants with approximately 211 million head, representing 15% of world's beef production, in an area of 170 million hectares of grasslands, mostly cultivated with Brachiaria spp. Although nutrient reduction due to increased atmospheric carbon dioxide (CO2) concentration has already been verified in important crops, studies evaluating its effects on fiber fractions and elemental composition of this grass genus are still scarce. Therefore, a better understanding of the effects of elevated CO2 on forage quality can elucidate the interaction between forage and livestock production and possible adaptations for a climate change scenario. The objective of this study was to evaluate the effects of contrasting atmospheric CO2 concentrations on biomass production, morphological characteristics, fiber fractions, and elemental composition of Brachiaria decumbens (cv. Basilisk). METHODS: A total of 12 octagonal rings with 10 m diameter were distributed in a seven-ha coffee plantation and inside each of them, two plots of 0.25 m2 were seeded with B. decumbens (cv. Basilisk) in a free air carbon dioxide enrichment facility. Six rings were kept under natural conditions (≈390 µmol mol-1 CO2; Control) and other six under pure CO2 flux to achieve a higher concentration (≈550 µmol mol-1 CO2; Elevated CO2). After 30 months under contrasting atmospheric CO2 concentration, grass samples were collected, and then splitted into two portions: in the first, whole forage was kept intact and in the second portion, the leaf, true stem, inflorescence and senescence fractions were manually separated to determine their proportions (%). All samples were then analyzed to determine the fiber fractions (NDF, hemicellulose, ADF, cellulose, and Lignin), carbon (C), nitrogen (N), potassium (K), calcium (Ca), sulfur (S), phosphorus (P), iron (Fe), and manganese (Mn) contents and N isotopic composition. RESULTS: Elevated atmospheric CO2 concentration did not influence biomass productivity, average height, leaf, stem, senescence and inflorescence proportions, and fiber fractions (p > 0.05). Calcium content of the leaf and senescence portion of B. decumbens were reduced under elevated atmospheric CO2 (p < 0.05). Despite no effect on total C and N (p > 0.05), lower C:N ratio was observed in the whole forage grown under elevated CO2 (p < 0.05). The isotopic composition was also affected by elevated CO2, with higher values of δ15N in the leaf and stem portions of B. decumbens (p < 0.05). DISCUSSION: Productivity and fiber fractions of B. decumbens were not influenced by CO2 enrichment. However, elevated CO2 resulted in decreased forage Ca content which could affect livestock production under a climate change scenario.