Review: Strategies for enteric methane mitigation in cattle fed tropical forages.

Methane (CH4) is a greenhouse gas (GHG) produced and released by eructation to the atmosphere in large volumes by ruminants. Enteric CH4 contributes significantly to global GHG emissions arising from animal agriculture. It has been contended that tropical grasses produce higher emissions of enteric CH4 than temperate grasses, when they are fed to ruminants. A number of experiments have been performed in respiration chambers and head-boxes to assess the enteric CH4 mitigation potential of foliage and pods of tropical plants, as well as nitrates (NO3-) and vegetable oils in practical rations for cattle. On the basis of individual determinations of enteric CH4 carried out in respiration chambers, the average CH4 yield for cattle fed low-quality tropical grasses (>70% ration DM) was 17.0 g CH4/kg DM intake. Results showed that when foliage and ground pods of tropical trees and shrubs were incorporated in cattle rations, methane yield (g CH4/kg DM intake) was decreased by 10% to 25%, depending on plant species and level of intake of the ration. Incorporation of nitrates and vegetable oils in the ration decreased enteric CH4 yield by ∼6% to ∼20%, respectively. Condensed tannins, saponins and starch contained in foliages, pods and seeds of tropical trees and shrubs, as well as nitrates and vegetable oils, can be fed to cattle to mitigate enteric CH4 emissions under smallholder conditions. Strategies for enteric CH4 mitigation in cattle grazing low-quality tropical forages can effectively increase productivity while decreasing enteric CH4 emissions in absolute terms and per unit of product (e.g. meat, milk), thus reducing the contribution of ruminants to GHG emissions and therefore to climate change.

Effects of supplementation of Brachiaria brizantha cv. Piatá and Napier grass with Desmodium distortum on feed intake, digesta kinetics and milk production in crossbred dairy cows.

This study was planned to analyse the basis that make Brachiaria species with greater feeding value than Napier grass (Pennisetum purpureum) for lactating dairy cows. Forty lactating crossbred cows were stall-fed on Brachiariabrizantha cv. Piatá or Napier grass cv. French Cameroon supplemented (mixed on fresh matter basis) or unsupplemented with Desmodium distortum, a forage legume. All cows were fed on fresh matter basis under small-holder farming conditions. Results showed that B. brizantha cv. Piatá had higher contents of dry matter (DM), crude protein (CP) and organic matter (OM), but lower contents of neutral detergent fibre (NDF) and acid detergent fibre (ADF) than Napier grass (P < 0.001). The legume supplementation increased intakes of CP and metabolizable energy (ME; P < 0.001), with higher effect on cows fed B. brizantha cv. Piatá than on cows fed Napier grass. Average daily milk yield was lower on diets based on Napier grass than those based on B. brizantha cv. Piatá (P < 0.001). The retention time of the particle phase of digesta in the digestive tract was longer on Napier grass (83.1 h) than on B. brizantha cv. Piatá (62.8 h) (P < 0.05). It was concluded that in dairy cows, legume supplementation of B. brizantha cv. Piatá increases nutrient intake, hence resulting in higher milk yields than supplementation of Napier grass.

Altitude effects on technology and productivity of small bovine farms (milk meat) in Veracruz (Gulf of Mexico).

The dual-purpose bovine system represents 98.4% of the bovine livestock of Veracruz, the main cattle-producing state of Mexico. This system supplies calves to meat companies, a sector in which Veracruz has been the national leader in the last decade. The objective of the present study was to analyze the effect of the altitudinal zonation of farms on livestock technology and productivity in a microbasin of the Gulf of Mexico where small farms predominate. Structured interviews were applied to producers located in three altitudinal zones (at average altitudes of 50, 140, and 450 m, respectively, for lower, middle, and upper zones). Sample size was 135 farms having similar land surface (within a range of 15-22 ha). The results indicated multiple differences among farms located in the three zones. Farms in the middle and lower zones presented higher productive indicators than those in the upper zone. Differences in herd structure and management resulted in important differences in productivity, income, and profits in milk and calf production. We concluded from this study that altitudinal zonation in Veracruz had a clear effect on the differentiation of small farms, which are representative of dual-purpose cattle. The upper zone performs cattle activity under conditions with greater disadvantages in the analyzed region.

Tolerance and phytoremediation potential of four tropical grass species to land-applied drill cuttings.

This work evaluated the tolerance and phytoremediation potential of four tropical grasses over a 12-week period, with a view to assessing their suitability for land farming of oil-based drill cuttings. It considered four grass species, namely, guinea grass (Megathyrsus maximus), spear grass (Imperata cylindrica), gamba grass (Andropogon gayanus), and elephant grass (Pennisetum purpureum). The treatments involved growing each of the four grasses on a mixture of 3:1 soil/drill-cuttings ratio, after failed trials with mix ratios ranging from 1:3 to 2:1 soil/drill-cuttings ratio, and on uncontaminated soil. The TPH concentration dropped by 27-81% from 4805 mg kg-1 in the 3:1 soil/drill-cuttings mixtures in the different treatments after 12 weeks. Better growth performance in the contaminated treatments, compared to uncontaminated controls, correlated with higher reduction in TPH and metals concentrations. The contaminated elephant grass treatment showed better plant height and leaf sizes than the uncontaminated control. The growth parameters of contaminated treatments with the other three grasses ranged from 29 to 75% of the corresponding uncontaminated controls. The results demonstrate that the relative suitability of the grasses for land farming of oil-based drill cuttings is in the order, elephant grass > guinea grass > gamba grass > spear grass.

Estudo metanalítico da resposta de gramíneas perenes de verão à adubação nitrogenada / Meta-analytic study of response of nitrogen fertilization on perennial summer grasses

O presente trabalho visou empregar um estudo metanalítico para sumarizar e analisar dados sobre adubação nitrogenada em pastagens formadas por gramíneas dos gêneros Brachiaria, Cynodon e Panicum. Foram selecionados 36 trabalhos de pesquisa realizados no Brasil nos últimos 10 anos, incluindo artigos científicos, teses e dissertações. Com base nos dados contidos nesses trabalhos, foi calculado o incremento relativo de matéria seca e de proteína bruta em relação ao tratamento controle (ausência de adubação nitrogenada) e a eficiência da utilização do nitrogênio na produção de matéria seca e proteína bruta. Os dados obtidos foram submetidos à análise de variância para efeito linear e quadrático em cada uma das variáveis dentro de cada gênero e, no caso de significância, foi realizada análise de regressão. A produção de matéria seca e de proteína bruta de forrageiras tropicais responde de forma expressiva à adubação nitrogenada, principalmente a segunda, porém o acréscimo nas doses de nitrogênio reduz a eficiência da adubação. Verificou-se uma frequente omissão de informações relevantes em trabalhos com adubação nitrogenada em pastagens.(AU)

The study aimed to employ a meta-analytic study to summarize and analyze data on nitrogen fertilization in grasslands formed by grasses of the genera Brachiaria, Cynodon and Panicum. A sample of 36 research projects carried out in Brazil in the last ten years, including scientific papers, theses and dissertations were selected. From the data contained in these works, relative dry matter and crude protein increment compared to the control treatment (absence of nitrogen fertilization) and the efficiency of nitrogen use in the production of dry matter and crude protein were calculated. Data were subjected to analysis of variance for linear and quadratic effect on each variable within each genus and, in case of significance, regression analysis was performed. The production of dry matter and crude protein of tropical forages responds greatly to nitrogen fertilization, especially the second, but the increase in nitrogen rates reduces the efficiency of fertilization. There was a frequent omission of relevant information in scientific works on nitrogen fertilization in grasslands.(AU)

Non-destructive Phenotyping to Identify Brachiaria Hybrids Tolerant to Waterlogging Stress under Field Conditions.

Brachiaria grasses are sown in tropical regions around the world, especially in the Neotropics, to improve livestock production. Waterlogging is a major constraint to the productivity and persistence of Brachiaria grasses during the rainy season. While some Brachiaria cultivars are moderately tolerant to seasonal waterlogging, none of the commercial cultivars combines superior yield potential and nutritional quality with a high level of waterlogging tolerance. The Brachiaria breeding program at the International Center for Tropical Agriculture, has been using recurrent selection for the past two decades to combine forage yield with resistance to biotic and abiotic stress factors. The main objective of this study was to test the suitability of normalized difference vegetation index (NDVI) and image-based phenotyping as non-destructive approaches to identify Brachiaria hybrids tolerant to waterlogging stress under field conditions. Nineteen promising hybrid selections from the breeding program and three commercial checks were evaluated for their tolerance to waterlogging under field conditions. The waterlogging treatment was imposed by applying and maintaining water to 3 cm above soil surface. Plant performance was determined non-destructively using proximal sensing and image-based phenotyping and also destructively via harvesting for comparison. Image analysis of projected green and dead areas, NDVI and shoot biomass were positively correlated (r ≥ 0.8). Our results indicate that image analysis and NDVI can serve as non-destructive screening approaches for the identification of Brachiaria hybrids tolerant to waterlogging stress.

Leaf transcriptome of two highly divergent genotypes of Urochloa humidicola (Poaceae), a tropical polyploid forage grass adapted to acidic soils and temporary flooding areas.

BACKGROUND: Urochloa humidicola (Koronivia grass) is a polyploid (6x to 9x) species that is used as forage in the tropics. Facultative apospory apomixis is present in most of the genotypes of this species, although one individual has been described as sexual. Molecular studies have been restricted to molecular marker approaches for genetic diversity estimations and linkage map construction. The objectives of the present study were to describe and compare the leaf transcriptome of two important genotypes that are highly divergent in terms of their phenotypes and reproduction modes: the sexual BH031 and the aposporous apomictic cultivar BRS Tupi. RESULTS: We sequenced the leaf transcriptome of Koronivia grass using an Illumina GAIIx system, which produced 13.09 Gb of data that consisted of 163,575,526 paired-end reads between the two libraries. We de novo-assembled 76,196 transcripts with an average length of 1,152 bp and filtered 35,093 non-redundant unigenes. A similarity search against the non-redundant National Center of Biotechnology Information (NCBI) protein database returned 65 % hits. We annotated 24,133 unigenes in the Phytozome database and 14,082 unigenes in the UniProtKB/Swiss-Prot database, assigned 108,334 gene ontology terms to 17,255 unigenes and identified 5,324 unigenes in 327 known metabolic pathways. Comparisons with other grasses via a reciprocal BLAST search revealed a larger number of orthologous genes for the Panicum species. The unigenes were involved in C4 photosynthesis, lignocellulose biosynthesis and flooding stress responses. A search for functional molecular markers revealed 4,489 microsatellites and 560,298 single nucleotide polymorphisms (SNPs). A quantitative real-time PCR analysis validated the RNA-seq expression analysis and allowed for the identification of transcriptomic differences between the two evaluated genotypes. Moreover, 192 unannotated sequences were classified as containing complete open reading frames, suggesting that the new, potentially exclusive genes should be further investigated. CONCLUSION: The present study represents the first whole-transcriptome sequencing of U. humidicola leaves, providing an important public information source of transcripts and functional molecular markers. The qPCR analysis indicated that the expression of certain transcripts confirmed the differential expression observed in silico, which demonstrated that RNA-seq is useful for identifying differentially expressed and unique genes. These results corroborate the findings from previous studies and suggest a hybrid origin for BH031.

Intake, milk production and weight change curves for lactating Holstein x Zebu cows under grazing / Consumo, curvas de lactado e variado de peso de vacas Holandês x Zebu em pastejo

The purpose of this study was to evaluate feed intake and develop lactation and weight change curves for Holstein x zebu cows under grazing. Eighteen F1 cows were used, divided into three treatments; 6 were Holstein x Gir (HGI), 6 were Holstein x Guzerat (HGU), and another 6 were Holstein x Nelore (HNE), under the feeding conditions of pasture plus concentrate with 22 percent of crude protein (CP). To estimate individual feed intake at pasture, 2 markers were used: titanium dioxide to estimate fecal dry matter (DM) excretion, and the indigestible acid detergent fiber (iADF) to estimate individual pasture intake. The Wood (1967) model was used to evaluate milk yield and the parameters were estimated for each genetic group, as follows: HGI = 17.2667*t0.0652*e-0.00424t; HGU = 18.1470*t0.0332*e-0.00408t; and HN = 14.2836*t0.1059*e-0.00552t. The NEFA contents varied according to different genetic groups (P<0.001). It was concluded that the estimated peak DMI occurs during the sixth week of lactation, when the DMI by the different genetic groups was stabilized. The HGI cows have greater cumulative production at 305-d...

O objetivo deste estudo foi avaliar o consumo de vacas Holandês x Zebu sob pastejo e desenvolver curvas de lactado e variado de peso para elas. Dezoito vacas F1 foram utilizadas, divididas em três tratamentos: seis foram Holandês x Gir (HGI), seis foram Holandês x Guzerá (HGU, e outras seis foram Holandês x Nelore (HNE), sob as mesmas condições de alimentado com pasto e concentrado com 22 por cento de proteína bruta (PB). Para estimar o consumo individual, dois indicadores foram utilizados: dióxido de titânio para estimar a excreto de matéria seca fecal (DM), e fibra em detergente ácido indigestível (FDAi) para estimar a ingestão de pasto. O modelo de Wood (1967) foi utilizado para avaliar a produto de leite, e os parâmetros foram estimados para cada grupo genético, conforme a seguir: HGI = 17.2667*t0.0652*e-0.00424t; HGU = 18.1470*t0.0332*e-0.00408t; e HN = 14.2836*t0.1059*e-0.00552t. O conteúdo de ácidos graxos não esterificados (AGNE) variou de acordo com os diferentes grupos genéticos (P<0,001). Concluiu-se que o pico estimado para CMS ocorre durante a sexta semana de lactado, quando o CMS pelos diferentes grupos genéticos foi estabilizado. As vacas HGI têm maior produto de leite acumulada aos 305-d...

Seasonal variation of soluble carbohydrates and starch in Echinolaena inflexa, a native grass species from the Brazilian savanna, and in the invasive grass Melinis minutiflora / Variações sazonais de carboidratos solúveis e amido em Echinolaena inflexa, uma espécie nativa do cerrado, e na gramínea invasora Melinis minutiflora

Echinolaena inflexa (Poir.) Chase is an abundant C3 grass species with high biomass production in the Brazilian savanna (cerrado); Melinis minutiflora Beauv. is an African C4 forage grass widespread in cerrado and probably displacing some native herbaceous species. In the present work, we analysed seasonally the content and composition of soluble carbohydrates, the starch amounts and the above-ground biomass (phytomass) of E. inflexa and M. minutiflora plants harvested in two transects at 5 and 130 m from the border in a restrict area of cerrado at the Biological Reserve and Experimental Station of Mogi-Guaçu (SP, Brazil). Results showed that water soluble carbohydrates and starch amounts from the shoots of both species varied according to the time of the year, whilst in the underground organs, variations were observed mainly in relation to the transects. Marked differences in the pattern of the above-ground biomass production between these two grasses relative to their location in the Reserve were also observed, with two peaks of the invasive species (July and January) at the Reserve border. The differences in carbohydrate accumulation, partitioning and composition of individual sugars concerning time of the year and location in the Reserve were more related to the annual growth cycle of both grasses and possibly to specific physiological responses of M. minutiflora to disturbed environments in the Reserve border.

Echinolaena inflexa (Poir.) Chase é uma gramínea C3 muito abundante em áreas de cerrado e com alta produção de biomassa. Melinis minutiflora Beauv. é uma gramínea C4 de origem africana introduzida no Brasil para fins forrageiros, que se espalhou amplamente por áreas de cerrado, provavelmente deslocando espécies nativas. No presente trabalho, o conteúdo e a composição de carboidratos solúveis, o teor de amido e a biomassa aérea foram analisados sazonalmente em plantas de E. inflexa e M. minutiflora coletadas em dois transectos, a 5 e 130 m da borda da Reserva Biológica e Estação Experimental de Mogi-Guaçu, uma área restrita de cerrado (SP, Brasil). Os resultados mostraram que os carboidratos solúveis e o conteúdo de amido da parte aérea de ambas as espécies variaram de acordo com a época do ano, enquanto que nos órgãos subterrâneos as variações foram observadas principalmente em relação aos transectos. Diferenças marcantes no padrão de distribuição de biomassa aérea das duas espécies em relação à localização na reserva também foram observadas, com dois picos de produção da espécie invasora (em julho e janeiro) na borda da reserva. As diferenças observadas no acúmulo de carboidratos, partição e composição dos açúcares em relação à época do ano e localização na reserva foram mais relacionadas ao ciclo anual de crescimento de ambas as espécies e possivelmente a respostas fisiológicas específicas de M. minutiflora a ambientes perturbados na borda da reserva.

Effects of irradiance on non-structural carbohydrates, growth, and hypoglycemic activity of Rhynchelytrum repens (Willd.) C.E. Hubb. (Poaceae)

Irradiance is a crucial factor in plant development. Different radiant energy levels cause different responses related to plant growth and the production and distribution of dry matter. Considering the relationship between light availability and metabolism of carbohydrates and derived compounds, the aim of this work was to assess the effects of irradiance on non-structural carbohydrate contents and composition, as well as on the hypoglycemiant activity of Rhynchelytrum repens, a pantropical grass species popularly used for diabetes treatment. Plants of R. repens growing under natural irradiance (NI) showed increased content of total soluble carbohydrate (TSC), higher fluctuations in starch content (SC) and higher number of tillers. The flowering process of these plants was preceded by an increase in sucrose. However, their water content was low when compared to that of plants cultivated under low irradiance (LI). The ratio root/aerial organs and SC showed no significant differences in plants grown under LI, although TSC increased and a lower number of tillers were observed during the experimental period. In both conditions, sucrose was the ubiquitous sugar and seemed to be involved in the flowering process. A reduction in the blood sugar level was observed through the intra-peritoneal (IP) administration of the precipitate of aqueous extracts obtained from plants growing in both conditions of light; the supernatant fraction showed no hypoglycemic effect.

A irradiância é um fator crucial em reações vitais para o crescimento e desenvolvimento das plantas. A utilização da energia radiante pelos vegetais afeta diferentes respostas em relação ao padrão de desenvolvimento e à produção de matéria seca e sua conseqüente distribuição. Tendo em vista a intrínseca relação entre disponibilidade de luz, acúmulo de biomassa e metabolismo de carboidratos e compostos relacionados, os objetivos deste trabalho foram avaliar o efeito da irradiância sobre o conteúdo e a composição dos carboidratos não-estruturais, sobre o desenvolvimento e sobre a atividade hipoglicemiante de Rhynchelytrum repens, uma gramínea pantropical de origem africana utilizada popularmente no tratamento de diabetes. O cultivo a pleno sol (PS) estimulou aumento no conteúdo de carboidratos solúveis totais (CST), no perfilhamento das plantas e nas flutuações do conteúdo de amido (CA). O florescimento dessas plantas foi precedido por um aumento de CST, especialmente de sacarose. Foi observado também menor conteúdo de água nas plantas sob PS quando comparado com as plantas cultivadas sob irradiância reduzida (IR). Nesta última condição, o CA e a razão raiz/parte aérea não sofreram alterações significativas, porém houve aumento no conteúdo de CST ao longo do período experimental, menor grau de perfilhamento e formação de raízes adventícias aéreas. Em ambas as condições de luminosidade, a sacarose foi o açúcar mais abundante e com maiores variações. Esse açúcar parece estar envolvido nos processos de florescimento da espécie. Uma redução no nível de glicose plasmática foi observada a partir da administração do precipitado do extrato aquoso de R. repens obtido de plantas cultivadas em PS e IR, não havendo diferença significativa entre os tratamentos. A fração sobrenadante não apresentou efeito hipoglicemiante.

Retenção do fósforo de fenos de gramíneas tropicais em ovinos

One experiment was conducted using five adult sheep fed on four tropical grass hays to determine phosphorus (P) retention. The experiment consisted of four periods of 21 days (14 days adaptation and seven days faeces collection). The treatments were: A) molasses grass (Melinis minutiflora), B) brachiaria grass (Brachiaria decumbens), C) coastcross grass (Cynodon dactilon) and D) Guinea grass (Panicum maximum). Phosphorus concentrations were 0.05%, 0.07%, 0.11% and 0.18% for treatments A, B, C and D, respectively. The effects of treatment, period and animal were evaluated by ortogonal polynomials and the contrasts by F test. Negative P balances were produced in treatments A, B and C (-13.05, -9.36 and -8.26mg/kg LW/day, respectively) which were not significantly different from each other. Positive P balance of 8.14mg/kg LW/day was produced in treatment D, which was significantly higher (P 0.05) than treatments A, B and C. Endogenous losses of 15.5mg P/kg LW/day were estimated using regression analysis. The average P retention coefficient of the hays was 0.37. A relationship between P intake and P balance showed that an intake of approximately 44mg P/kg LW/day was necessary to produce a zero P balance.

Mediu-se a retenção do fósforo de quatro gramíneas tropicais, capim-gordura (Melinis minutiflora), capim-braquiária (Brachiaria decumbens), capim-coastcross (Cynodon dactilon) e capim-colonião (Panicum maximum), em cinco ovinos por meio de ensaios de balanço de fósforo. O experimento constou de quatro fases, cada uma com duração de 21 dias (14 dias de adaptação à dieta e sete dias de colheita de fezes), totalizando 20 observações. A análise dos dados foi feita por polinômios ortogonais, testando-se os efeitos de tratamento, de período e de animal, e os contrastes foram comparados pelo teste F. A retenção de fósforo foi negativa nos fenos dos capins gordura, braquiária e coastcross e positiva no feno do capim-colonião. Por análise de regressão, a perda fecal do fósforo endógeno foi estimada em 15,5mg/kg PV/dia e o coeficiente médio de retenção foi de 0,37. Pela razão entre o balanço e a ingestão, estimou-se que o consumo de fósforo necessário para alcançar o equilíbrio foi de 44mg/kg PV/dia.