Phyllochron estimates on agronomic potential and physiological quality of millet / Estimativas do filocrono no potencial agronômico e na qualidade fisiológica do milheto

Millet is largely explored for a diversity of applications. The use of millet high-quality seeds is essential to increase grain yield. Accordingly, the purposeof this studywas to evaluate the yield variability of milletplants from higher and lower-quality seeds in the expression of dry matter yield parameters. The studywas conducted in the experimental and didactic area of IFRS -campusIbirubá, Rio Grande do Sul, Brazil, with a completely randomized design. The treatments were plants from seeds of higher (HQS) and lower (LQS) quality and two season crops (2015/16 and 2017/18) in eight replications. Theemergence speed was appliedto identify plants from seeds of different qualities. The phyllochron, leaf number, height, stem diameter, number of nodes, and dry mass yield were the agronomic components evaluatedfor this study. Meteorological information was used to calculate phyllochron, water deficit, and average temperature. The collected data were submitted for analysis of variance and the Tukey test at a 5% probability of error. The HQS expressed lower phyllochron and most significant agronomic components. Furthermore, the 2015/16 crop had the lowest water deficit and obtained the best results.(AU)

O milheto é amplamente explorado para uma diversidade de aplicações. O uso de sementes de milheto de alta qualidade é essencial para aumentar a produtividade de grãos. Nesse sentido, o propósito deste estudo foi avaliar a variabilidade da produtividade de plantas de milheto provenientes de sementes de melhor e de menor qualidade na expressão dos parâmetros de produção de matéria seca. O estudo foi realizado na área experimental e didática do IFRS - campus Ibirubá, Rio Grande do Sul, Brasil, com delineamento inteiramente casualizado. Os tratamentos foram plantas provenientes de sementes de qualidade superior (SAS) e inferior (SQI) e duas safras (2015/16 e 2017/18) em oito repetições. A velocidade de emergência foi aplicada para identificar plantas a partir de sementes de diferentes qualidades. O filocrono, número de folhas, altura, diâmetro do caule, número de nós e rendimento de massa seca foram os componentes agronômicos avaliados para este estudo. As informações meteorológicas foram utilizadas para calcular o filocrono, o déficit hídrico e a temperatura média. Os dados coletados foram submetidos à análise de variância e ao teste de Tukey a 5% de probabilidade de erro. O SQS expressou menor filocrono e componentes agronômicos mais significativos. Ainda, a safra 2015/16 apresentou o menor déficit hídrico e obteve os melhores resultados.(AU)

Combined agricultural practices in millet and cactus: phyllochron, structural characteristics and relations with yield

Variation in rainfall affects crops; therefore, agricultural practices become essential for forage production in semi-arid regions. This study aimed to evaluate the influence of different agricultural practices on phyllochron, structural characteristics of forage cactus and millet, and their relations with crop yield using the principal component analysis (PCA). The design was in randomized blocks, with six treatments: sole cropped cactus without straw mulching, sole cropped cactus with straw mulching, sole cropped millet without straw mulching, sole cropped millet with straw mulching, and cactus intercropping with millet, with and without straw mulching, each with four replicates. There were three cactus cycles and nine millet cycles (three cycles of cultivars BRS1501 and six of IPA Bulk-1-BF). Biometric parameters were evaluated monthly, while yield was determined after the crop harvest. Phyllochron was determined with the regression analysis. The PCA was applied to structural characteristics and yield. The systems adopted did not influence the structural characteristics of cactus and millet ( p > 0.05), except for cladode thickness, which increased with straw mulching. Phyllochron of the millet reduced when the crop was intercropped. The structural characteristics of cladode length, width, and thickness influenced crop yield, mainly in systems with straw mulching. Straw mulching and intercropping alter phyllochron of cactus and millet. The adoption of straw mulching has a more significant relationship with cactus yield, whereas biometric variables influence crop yield for millet, not the cropping system.(AU)

Potential of elephant grass genotypes silages as exclusive roughage on tissue composition and meat quality of lambs: a preliminary study / Potencial de silagens de genótipos de capim-elefante como volumoso exclusivo sobre a composição tecidual e a qualidade da carne de cordeiros: um estudo preliminar

This study aimed to evaluate the effects of diets containing elephant grass genotypes silages as exclusive roughage on leg tissue composition, and physicochemical characteristics of meat of lambs. Twenty-four crossbred male lambs with an average initial body weight of 20.29±2.66kg were distributed in a complete randomized design with three treatments and eight replicates. The treatments consisted of three silages of elephant grass genotypes (IRI-381, Elephant B or Mott), without additives or wilting, as the only roughage. The diets did not affect (P>0.05) the dry matter (898.70±60.10 g/day), crude protein (128.93±6.91g/day), total digestible nutrients (690.20±91.82g/day) intakes, body weight at slaughter (24.83±2.79kg), and carcass yields (P>0.05). The tissue composition of the leg did not differ significantly between silages of elephant grass genotypes (P>0.05). No difference (P>0.05) for the physicochemical characteristics of meat from lambs fed diets tested was observed. Therefore, our results indicate that diets containing 50% elephant grass genotypes silages (IRI-381, Elephant B or Mott), harvested at 60 days of growth, have potential for use in lambs feeding.

Este estudo teve como objetivo avaliar os efeitos de dietas contendo silagens de genótipos de capim-elefante como volumoso exclusivo sobre a composição tecidual da perna e nas características físico-químicas da carne de cordeiros. Vinte e quatro cordeiros machos mestiços, com peso corporal inicial médio de 20,29±2,66kg, foram distribuídos em delineamento inteiramente ao acaso, com três tratamentos e oito repetições. Os tratamentos consistiram de três silagens de genótipos de capim-elefante (IRI-381, Elephant B ou Mott), sem aditivos ou emurchecimento, como único volumoso. As dietas não afetaram (P>0,05) os consumos de matéria seca (898,70 ± 60,10g/dia), proteína bruta (128,93±6,91g/dia) e nutrientes digestíveis totais (690,20±91,82g/dia), peso corporal ao abate (24,83±2,79kg) e rendimentos de carcaça (P>0,05). A composição tecidual da perna não diferiu significativamente entre as silagens dos genótipos de capim-elefante (P>0,05). Não foi observada diferença (P>0,05) para as características físico-químicas da carne dos cordeiros alimentados com as dietas testadas. Portanto, os resultados indicam que dietas contendo 50% de silagens de genótipos de capim-elefante (IRI-381, Elephant B ou Mott), colhidos aos 60 dias de crescimento, têm potencial para uso na alimentação de cordeiros.

Untreated or ammoniated cotton gin trash in the ensiling of elephant grass reduces silage quality

This study examined the inclusion of untreated or urea-ammoniated CGT on the chemical composition, pH, gas, and effluent losses, dry matter recovery (DMR), and aerobic stability of elephantgrass silage. The experiment was laid out in a randomized design with a 3 × 3 factorial arrangement represented by three levels of inclusion of CGT during ensiling (0, 5, or 10%) and three levels of ammoniation of CGT with urea before ensiling (0, 4 or 8% for 28 days), using four replications. Data were subjected to analysis of variance and Tukey's test, considering a 5% significance level. The pH and DM, NDIN, ADIN, NDF and ADF contents of the silages increased (p<0.05) with the inclusion of CGT, regardless of ammoniation. The lowest (p<0.05) effluent loss was achieved using 10% of CGT ammoniated with 8% urea. In contrast, the elephantgrass silage exhibited the lowest (p<0.05) gas loss and the greatest (p<0.05) DMR. The inclusion of CGT compromised the aerobic stability of the silage. Therefore, the inclusion of CGT ­either untreated or ammoniated ­in the ensiling of elephantgrass is not recommended.(AU)

Characterization and genetic diversity in Paspalum notatum Flügge accessions: Morphological and geographical distance

The objective of this work was to describe morphology and grouping of Paspalum notatum accessions, based on multicategorical data which discards the redundant variables for quantification of genetic diversity. We also tested the hypothesis that geographical distance was correlated with morphological divergence. In our study, multivariate analyzes successfully demonstrated the geographic and morphological variability of the P. notatum accessions characterized. Many of these evaluated accessions can be included in future genetic improvement programs. Based on two methodologies for discarding variables, it was possible to identify the potentially important morphological characteristics from genetic diversity studies and characterize new accessions aimed at improving forage and seed production. The methodologies used to discard variables are biometric tools that can be used successfully in future plant breeding programs, especially when a large number of traits and accessions are being evaluated. Although significant, geographic distance had a low association with morphological traits. This indicated the need to use other characteristics, such as forage and seed yield, in addition to molecular analysis. Our analyzes showed genetic variability in P. notatum for all the characteristics studied.(AU)

The occurrence of rhizobacteria from Paspalum genotypes and their effects on plant growth

This work aimed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from 10 Paspalum genotypes and evaluate the effect of their inoculation on P. regnellii, P. atratum, and P. malacophyllum genotypes. The bacterial population ranged from undetectable to 107 bacterial cells per gram of fresh matter in the Paspalum genotypes. Initially, we isolated 164 bacteria from rhizospheric soil and roots of the Paspalum genotypes using media N-free LG agar plate, semi-solid NFb, and LGI. The isolates were characterized genetically and physiologically. The sequencing of 16S rRNA showed the presence of many genera, and some are new in association with Paspalum. The most common was Bacillus followed by Rhizobium, Paraburkholderia, Enterobacter, Cupriavidus, Pseudomonas, Dyadobacter and Acinetobacter. Thirty-eight per cent of isolates produced siderophores, 25 % produced solubilized phosphate, and only 9 % produced indolic compounds. Three greenhouse experiments were performed in randomized blocks with six replicates using representative bacterial strains isolated from P. regnellii, P. malacophyllum and P. atratum cv. Pojuca. We also included strain Sp245 (Azospirillum baldaniorum), uninoculated control, and nitrogen control (150 kg N ha–1). There was an increase of up to 53 % in shoot dry matter in P. regnellii inoculated with strain Sp245 and the shoots accumulated more N. In contrast, only small effects were observed for the other Paspalum genotypes inoculated with PGPR from the host genotypes. This study shows a high diversity of diazotrophic rhizosphere bacteria and suggests no strain specificity between the bacterial isolates and the Paspalum genotypes.

Morphometry, productivity and bromatological analisis of purple elephant grass according to nitrogen fertilization

Pennisetum purp ureum Schum

Sugar content variation in elephant grass germplasm / Variação do teor de açúcar em germoplasma de capim-elefante

The objective of this study was to estimate sugar content variation (°Brix) in 95 accessions from the elephant grass germplasm active bank of Embrapa Dairy Cattle research center, located in Coronel Pacheco, MG, Brazil. The accessions with the highest sugar content were identified, and the effect of plant age on sugar concentration was evaluated. The experiment was conducted in randomized blocks design with two replications. Sugar content analysis occurred twice during the growth-cycle (at 70 and 100 days) along two points of the stem, one 30 cm from the base and the other at the midpoint. The analysis of variance considered the split plot model, with accessions as main plots and plant age as subplots. The means were compared using the Scott Knott test. While there was sugar content variation between accessions, increased plant age had no significant effect on the sugar content. However, some accessions did have a significant increase or decrease in sugar content as they aged. The highest and lowest mean sugar content was 6.96% (in the accession BAG80) and 4.03% (in the accession BAG13) °Brix, respectively.

O objetivo deste estudo foi estimar a variação do teor de açúcar (°Brix) existente entre 95 acessos do banco ativo de germoplasma de capim-elefante da Embrapa Gado de Leite, localizado no campo experimental de Coronel Pacheco. Foram identificados os acessos com maior teor de açúcar, bem como avaliado o efeito da idade da planta sobre a variação da concentração de açúcar. O experimento foi conduzido em blocos ao acaso com duas repetições, 95 genótipos, duas idades de planta, 70 e 100 dias de crescimento, e análise do teor de açúcar em duas secções amostradas à 30 cm da base e na metade do colmo. A análise de variância considerou modelo de parcela subdividida no tempo, sendo os acessos, as parcelas e a idade da planta as subparcelas. As médias foram comparadas pelo teste de Scott Knott. Observou-se variação no teor de açúcar entre os acessos, porém não foi observado efeito significativo no teor de açúcar devido ao aumento da idade da planta. Entretanto, alguns acessos apresentaram interação significativa com aumento ou redução do teor de açúcar em decorrência do aumento da idade da planta. O acesso de maior média de teor de açúcares entre as duas idades foi BAG80, com 6,96%, e o de menor foi BAG13, com 4,03%.

Sugar content variation in elephant grass germplasm / Variação do teor de açúcar em germoplasma de capim-elefante

The objective of this study was to estimate sugar content variation (°Brix) in 95 accessions from the elephant grass germplasm active bank of Embrapa Dairy Cattle research center, located in Coronel Pacheco, MG, Brazil. The accessions with the highest sugar content were identified, and the effect of plant age on sugar concentration was evaluated. The experiment was conducted in randomized blocks design with two replications. Sugar content analysis occurred twice during the growth-cycle (at 70 and 100 days) along two points of the stem, one 30 cm from the base and the other at the midpoint. The analysis of variance considered the split plot model, with accessions as main plots and plant age as subplots. The means were compared using the Scott Knott test. While there was sugar content variation between accessions, increased plant age had no significant effect on the sugar content. However, some accessions did have a significant increase or decrease in sugar content as they aged. The highest and lowest mean sugar content was 6.96% (in the accession BAG80) and 4.03% (in the accession BAG13) °Brix, respectively.(AU)

O objetivo deste estudo foi estimar a variação do teor de açúcar (°Brix) existente entre 95 acessos do banco ativo de germoplasma de capim-elefante da Embrapa Gado de Leite, localizado no campo experimental de Coronel Pacheco. Foram identificados os acessos com maior teor de açúcar, bem como avaliado o efeito da idade da planta sobre a variação da concentração de açúcar. O experimento foi conduzido em blocos ao acaso com duas repetições, 95 genótipos, duas idades de planta, 70 e 100 dias de crescimento, e análise do teor de açúcar em duas secções amostradas à 30 cm da base e na metade do colmo. A análise de variância considerou modelo de parcela subdividida no tempo, sendo os acessos, as parcelas e a idade da planta as subparcelas. As médias foram comparadas pelo teste de Scott Knott. Observou-se variação no teor de açúcar entre os acessos, porém não foi observado efeito significativo no teor de açúcar devido ao aumento da idade da planta. Entretanto, alguns acessos apresentaram interação significativa com aumento ou redução do teor de açúcar em decorrência do aumento da idade da planta. O acesso de maior média de teor de açúcares entre as duas idades foi BAG80, com 6,96%, e o de menor foi BAG13, com 4,03%.(AU)

Strategic grazing management decreases nitrogen excretion intensity of dairy cows

There is limited information regarding both nitrogen (N) and energy partitioning of dairy cows grazing well–managed tropical pastures. The objective of this study was to investigate the N and energy partitioning of mid–lactation dairy cows on rotationally grazed elephant grass using two pre–grazing targets: 95 % or maximum canopy light interception (LI95% or LIMax) during regrowth. The study used 26 Holstein × Jersey dairy cows arranged in a randomized complete block design with three 40–day periods of sampling. Grazing at LI95% increased organic matter and crude protein intake by 20 % (p ≤ 0.05) which resulted in a 9 % increase in fat corrected milk yield (p ≤ 0.05) relative to LIMax. Cows grazing at LI95% had greater concentration of total volatile fatty acids, butyrate and valerate (p ≤ 0.05), and smaller acetate (p ≤ 0.05) than those grazing at LIMax. Intake of net energy for lactation (NEL) and NEL secreted in milk were greater (p ≤ 0.05), while partitioning of NEL towards maintenance tended to be greater (p = 0.07) for cows grazing at LI95% than those grazing at LIMax. Milk urea nitrogen and both urine and fecal N excretion were greater for cows grazing at LI95% (p ≤ 0.05), but N excretion intensity was lower than in cows grazing at LIMax (p ≤ 0.05). Strategic grazing management using the LI95% pre–grazing target increases N losses through both urine and feces; however, it reduces N excretion intensity of dairy cows by 9 %.

The occurrence of rhizobacteria from Paspalum genotypes and their effects on plant growth

This work aimed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from 10 Paspalum genotypes and evaluate the effect of their inoculation on P. regnellii, P. atratum, and P. malacophyllum genotypes. The bacterial population ranged from undetectable to 107 bacterial cells per gram of fresh matter in the Paspalum genotypes. Initially, we isolated 164 bacteria from rhizospheric soil and roots of the Paspalum genotypes using media N-free LG agar plate, semi-solid NFb, and LGI. The isolates were characterized genetically and physiologically. The sequencing of 16S rRNA showed the presence of many genera, and some are new in association with Paspalum. The most common was Bacillus followed by Rhizobium, Paraburkholderia, Enterobacter, Cupriavidus, Pseudomonas, Dyadobacter and Acinetobacter. Thirty-eight per cent of isolates produced siderophores, 25 % produced solubilized phosphate, and only 9 % produced indolic compounds. Three greenhouse experiments were performed in randomized blocks with six replicates using representative bacterial strains isolated from P. regnellii, P. malacophyllum and P. atratum cv. Pojuca. We also included strain Sp245 (Azospirillum baldaniorum), uninoculated control, and nitrogen control (150 kg N ha−1). There was an increase of up to 53 % in shoot dry matter in P. regnellii inoculated with strain Sp245 and the shoots accumulated more N. In contrast, only small effects were observed for the other Paspalum genotypes inoculated with PGPR from the host genotypes. This study shows a high diversity of diazotrophic rhizosphere bacteria and suggests no strain specificity between the bacterial isolates and the Paspalum genotypes.

The genotype does not influence the establishment of elephantgrass (Pennisetum purpureum Schum)

This study investigated whether genotype influences the establishment of Pennisetum purpureum Schumach. The experimental design was a randomized complete blocks with four treatments and eight replications (n=8). The treatments were four genotypes of P. purpureum, two classified as tall sizes: P. purpureum cv. Elephant B and cv. IRI 381; and two as dwarf types: P. purpureum cv. Mott and Taiwan A-146 2.37. They were planted in a tropical wet and dry region of Brazil. Tall genotypes showed superior field sprouting rates (p < 0.05), ranging between 95-99%, while dwarfs varied between 88-90%, however, Elephant B and IRI 381 produced a much lower average number of tillers (31 and 32 linear m-1, respectively), than Taiwan A-146 2.37 and Mott (56 and 41 linear m-1, respectively) (p < 0.05). Dwarf genotypes produced lower biomass yields (p < 0.05), but this was genotype-dependent and did not impact on their establishment. The levels of non-structural carbohydrates (NSC) (>10%) in the planted stems were associated with satisfactory field sprouting of the elephantgrass genotypes. Despite some variations between the genotypes in terms of sprouting, tillering, and growth rates, the kind of genotype had no major significance on the establishment of the elephantgrass.(AU)

Weed interference in caupi beans (Vigna unguiculata) grown in Januária, north of Minas Gerais, Brazil / Interferência de plantas daninhas em feijão-caupi (Vigna unguiculata) cultivado em Januária, norte de Minas Gerais, Brasil

The degree of weed interference in an agricultural crop is influenced by edaphoclimatic characteristics, the management used in the environment and the period of coexistence between the weeds and the crop of interest. This study aimed to determine periods of weed interference in cowpea (Vigna unguiculata-Fabaceae) var. BRS Potengi in the semiarid of northern Minas Gerais, Brazil. Treatments consisted of periods of control and coexistence of cowpea with weeds under irrigated cultivation (0, 7, 14, 21, 28, 35, 42, 49, 56, 63, and 77 days after crop emergence). At the end of each period of coexistence and harvest time, weeds were quantified and identified, and dry matter was determined. Stem diameter, number of pods per plant, and grain yield were obtained for cowpea. The main weeds found were Cenchrus echinatus, Panicum maximum, Eleusine indica (Poaceae), and Amaranthus retroflexus (Amaranthaceae). The period before interference (PBI) occurred up to 9 days after emergence, the total period of interference prevention (TPIP) occurred up to 23days after emergence, and critical period of interference prevention (CPIP) was observed between 9 and 23days after emergence. Weed interference during the entire cowpea cycle reduced yield by 37% when compared to the control treatment.

O grau de interferência de plantas daninhas em uma cultura agrícola é influenciado pelas características edafoclimáticas, pelo manejo utilizado no ambiente e pelo período de convivência entre as plantas daninhas e a cultura de interesse. Este trabalho teve como objetivo determinar períodos de interferência de plantas daninhas em feijão-caupi (Vigna unguiculata-Fabaceae) var. BRS Potengi no semiárido do norte de Minas Gerais, Brasil. Os tratamentos consistiram em períodos de controle e convivência do feijão-caupi com plantas daninhas sob cultivo irrigado (0, 7, 14, 21, 28, 35, 42, 49, 56, 63 e 77 dias após a emergência da cultura). Ao final de cada período de convivência e época de colheita, as plantas daninhas foram quantificadas e identificadas, e a matéria seca foi determinada. O diâmetro do caule, número de vagens por planta e produtividade de grãos foram obtidos para o feijão-caupi. As principais plantas daninhas encontradas foram Cenchrus echinatus, Panicum maximum, Eleusine indica (Poaceae) e Amaranthus retroflexus (Amaranthaceae). O Período Anterior à Interferência (PAI) ocorreu até 9 dias após a emergência, o Período Total de Prevenção à interferência (PTPI) ocorreu até 23 dias após a emergência e o Período Crítico de Prevenção à Interferência (PCPI) foi observado entre 9 e 23 dias após a emergência. A interferência de plantas daninhas durante todo o ciclo do feijão-caupi reduziu a produtividade em 37% quando comparado ao tratamento controle.

Effect of microbial inoculant on the fermentation profile, nutritional value and microbial population on corn, sorghum, and pearl millet silages / Efeito do inoculante microbiano no perfil de fermentação, valor nutricional e população microbiana em silagens de milho, sorgo e milheto

The objective of the present study was to evaluate the use of microbial inoculant on the chemical composition, in vitro gas production, pH, dry matter losses, aerobic stability and microbial population on silages of corn, sorghum and pearl millet in plastic bags silos (without vacuum). The experiment was carried out in a randomized block design, in a 2 × 3 factorial scheme, with and without (control) inoculant consisting of Lactobacillus plantarum and Propionibacterium acidipropionici and on three crops, corn, sorghum and pearl millet, with four replicates. The use of the inoculant did not affect the chemical composition of the silages, except the crude protein (P = 0.0062) and lignin (P = 0.0567) contents. Gas production was neither affected (P > 0.05) by the inoculant nor by the crop. Regarding aerobic stability, we observed that the inoculant affected the temperature of the sorghum silage (P = 0.0123). The inoculant decreased the N-NH3 (P =0.0095) content and increased (P = 0.0441) the lactic acid bacteria population in the silages. Thus, the microbial inoculant did not improve the fermentation profile or nutritional value of corn, pearl millet and sorghum silages in plastic bag silos (without vacuum).(AU)

O objetivo do presente estudo foi avaliar o uso de inoculante bacteriano na composição química, produção de gás in vitro, pH, perdas de matéria seca, estabilidade aeróbia e população microbiana de silagens de milho, sorgo e milheto em silos de sacos plásticos (sem vácuo). O experimento foi conduzido em delineamento de blocos casualizados, em esquema fatorial 2 × 3, [Controle] sem inoculante e Lactobacillus plantarum e Propionibacterium acidipropionici e três culturas, milho, sorgo e milheto, com quatro repetições. O uso do inoculante não afetou a composição química das silagens, exceto proteína bruta (P = 0,0062) e lignina (P = 0,0567). A produção de gás não foi afetada (P > 0,05) pelo inoculante e nem entre as culturas. Na estabilidade aeróbia, observou-se que o inoculante afetou a temperatura da silagem de sorgo (P = 0,0123). O inoculante diminuiu o conteúdo de N-NH3 (P = 0,0095). O inoculante aumentou (P = 0,0441) a população de bactérias ácido-láticas nas silagens. Assim, o inoculante microbiano não melhorou o perfil fermentativo e o valor nutricional das silagens de milho, sorgo e milheto em silos de sacos plásticos (sem vácuo).(AU)

Evaluation of Megathyrsus maximus genotypes under water stress conditions

The objective was to evaluate the production of Megathyrsus maximusgenotypes (Syn. Panicum maximum), under different levels of water in the soil. This was a 5x5 factorial completely randomized design conducted in a greenhouse, combining five genotypes of M. maximus(B55, C10 and PM30, cv. Massai and cv. BRS Tamani) and five levels of soil field capacities (20%, 40%, 60%, 100% and 140%), with three replications. Dry matter production was evaluated: leaf, stem, dead material, root, shoot and total dry matters, as well as the number of tillers and leaf:stem and aboveground:root ratios. The qualitative factor (genotypes) was subjected to Duncan test at 5% probability. The quantitative factor (% field capacity) was subjected to regression, adopting 5% as a critical level of probability. There was no interaction between the factors for any of the evaluated characteristics. Significant differences amongthe genotypes were detected for tiller number, dead material dry mass, root and total dry mass and leaf:stem ratio. There was no significant effect of the percentage of field capacity on most of the characteristics, except for leaf:stem and aboveground:root ratios. Cultivar Massai showed the best forage production compared to the other genotypes, regardless of the percentage of field capacity evaluated. In general, the evaluated genotypes were more tolerant to excess water stress than to water deficit.(AU)

Potassium uptake kinetics in native forage grass species from Pampa Biome / Cinética de absorção de potássio em espécies de gramíneas forrageiras nativas do bioma Pampa

This study quantified K uptake kinetic parameters in grass species Paspalum notatum, Paspalum urvillei and Axonopus affinis to associate them with growth. Ten milliliters (10 ml) of nutrient solution were collected in two-liter pots - with five repetitions in 24 hours - in order to determine K concentrations in the samples. Shoot and root dry matter, root length, volume, diameter and surface area, as well as kinetic parameters associated with nutrient uptake (Vmax, Km, Cmin and I) were determined. Species P. notatum was the one presenting the highest root, shoot and total dry matter production, as well as the highest root volume. P. urvillei recorded the highest K content, which may be associated with thinner roots and greater root surface area. A. affinis recorded the highest Vmax value, which led to greater K uptake efficiency.

O estudo quantificou os parâmetros cinéticos de captação de K nas gramíneas Paspalum notatum, Paspalum urvillei e Axonopus affinis associados com o crescimento. Dez mililitros (10 ml) de solução nutritiva foram coletados em vasos de dois litros - com cinco repetições em 24 horas - para determinação das concentrações de K nas amostras. A matéria seca da parte aérea e raízes; comprimento, volume, diâmetro e área superficial radicular, bem como parâmetros cinéticos associados à absorção de nutrientes (Vmax, Km, Cmin e I) foram avaliados. A espécie P. notatum apresentou a maior produção de raiz, parte aérea e MS total, bem como o maior volume de raiz. P. urvillei apresentou o maior teor de K, que pode ser associado a raízes mais finas e resultando em maior área superficial. A. affinis registrou o maior valor de Vmax, o que levou a uma maior eficiência de absorção de K.

Teores de matéria seca e proteína bruta do Pennisetum purpureum schum cv. BRS Capiaçu em função da idade de corte / Dry matter and gross protein content of Pennisetum purpureum schum cv. BRS Capiaçu by cuttting age

O objetivo deste trabalho foi avaliar a influência das diferentes idades de corte sobre o teor de matéria seca e proteína bruta do capim BRS Capiaçu. O experimento iniciou-se com a seleção e corte das plantas matrizes para o maior aproveitamento do colmo, fez necessário eliminar as folhas superiores, pois as mesmas não brotam, e a retirada facilitou na distribuição do colmo na hora do plantio. O delineamento experimental foi realizado em blocos casualizados, totalizando quatro repetições. A unidade experimental constituiu-se de três linhas de plantio de 48,0 m de comprimento com espaçamento entre linhas de 1,5 m, totalizando 144 m². O experimento teve duração de 110 dias, sendo distribuído em três períodos: 60, 90 e 110 dias, somando assim, três idades de corte. Para a implantação da cultivar, foi realizado o preparo convencional do solo, uso do adubo para plantio na formulação NPK 4-30-10, na cobertura o fertilizante 20-05-20 conforme a análise química do solo e o plantio por colmos no sulco. Nas três idades de corte, as amostras coletadas foram acondicionadas em sacos plásticos identificados conforme o tratamento e repetição, posteriormente foram encaminhados para o laboratório. Os maiores valores de matéria seca foram obtidos com 90 e 110 dias de corte (p<0,05). Na variável proteína bruta, o maior valor foi observado aos 60 dias, porém, não diferindo do corte realizado aos 110 dias de idade (p>0.05). O corte realizado aos 110 dias favoreceu o aumento nos teores de matéria seca sem comprometer os teores de proteína bruta.

The objective of this work was to evaluate the influence of different cutting ages on the dry matter and crude protein content of BRS Capiaçu grass. The experiment began with the selection and cutting of the mother plants for the best use of the stem, it was necessary to eliminate the upper leaves, as they do not sprout, and the removal facilitated the distribution of the stem at the time of planting. The experimental design was carried out in randomized blocks, totaling four replications. The experimental unit consisted of three planting lines of 48.0 m in length with a spacing between rows of 1.5 m, totaling 144 m². The experiment lasted 110 days, being distributed in three periods: 60, 90 and 110 days, thus adding three cutting ages. For the implantation of the cultivar, the conventional soil preparation was carried out, the use of fertilizer for planting in the NPK 4-30-10 formulation, in the coverage the fertilizer 20-05-20 according to the chemical analysis of the soil and the planting by stalks in the furrow. At the three cutting ages, the samples collected were placed in plastic bags identified according to the treatment and repetition, and were later sent to the laboratory. The highest values of dry matter were obtained with 90 and 110 days of cutting (p<0.05). In the crude protein variable, the highest value was observed at 60 days of age, however, it did not differ from the cut performed at 110 days of age (p>0.05). The cut performed at 110 days favored an increase in dry matter contents without compromising crude protein contents.

Strategic grazing management decreases nitrogen excretion intensity of dairy cows

There is limited information regarding both nitrogen (N) and energy partitioning of dairy cows grazing well­managed tropical pastures. The objective of this study was to investigate the N and energy partitioning of mid­lactation dairy cows on rotationally grazed elephant grass using two pre­grazing targets: 95 % or maximum canopy light interception (LI95% or LIMax) during regrowth. The study used 26 Holstein × Jersey dairy cows arranged in a randomized complete block design with three 40­day periods of sampling. Grazing at LI95% increased organic matter and crude protein intake by 20 % (p ≤ 0.05) which resulted in a 9 % increase in fat corrected milk yield (p ≤ 0.05) relative to LIMax. Cows grazing at LI95% had greater concentration of total volatile fatty acids, butyrate and valerate (p ≤ 0.05), and smaller acetate (p ≤ 0.05) than those grazing at LIMax. Intake of net energy for lactation (NEL) and NEL secreted in milk were greater (p ≤ 0.05), while partitioning of NEL towards maintenance tended to be greater (p = 0.07) for cows grazing at LI95% than those grazing at LIMax. Milk urea nitrogen and both urine and fecal N excretion were greater for cows grazing at LI95% (p ≤ 0.05), but N excretion intensity was lower than in cows grazing at LIMax (p ≤ 0.05). Strategic grazing management using the LI95% pre­grazing target increases N losses through both urine and feces; however, it reduces N excretion intensity of dairy cows by 9 %.

Anaerobic co-digestion of swine manure and forage at two harvesting ages / Co-digestão anaeróbia dos dejetos de suínos e forragem em duas idades de colheita

The co-digestion of swine manure with vegetable waste is an alternative that can increase the production of biogas and methane generated by the isolated digestion of manure. However, recommendations that are based on the best ratio between manure and forage, as well as the age of harvest, are still scarce in the literature. This study was conducted to evaluate inclusions (0, 25, 50, 75 and 100%) of the total solids (TS) of Elephant grass (Pennisetum purpureum Schum) harvested at two ages medium age (MA) at 45 days of growth and advanced age (AA) at 90 days in co-digestion with swine manure, using an entirely randomized design in a 5x2 factorial scheme. Batch digesters were used and biogas production was monitored for 12 weeks. There was influence of forage age (P <0.05) on the degradation of solids and neutral detergent fiber, with higher values for the substrates containing MA forage. The highest CH4 yields were obtained by the substrates containing MA forage in the inclusion of 27.7 and 31.6%, being 253.7 and 222.2 L of CH4 per Kg of total or volatile solids. The age of the forages influenced the onset and persistence of biogas production, being advantageous only in the inclusion of 25% of MA forage. The AA forage inclusion is not recommended for co-digestion with swine manure.

A co-digestão dos dejetos suínos associados a resíduos vegetais é uma alternativa que pode elevar as produções de biogás e metano alcançadas pela digestão isolada do dejeto. No entanto, recomendações que se baseiem na melhor proporção entre dejeto e forragem, assim como na idade de colheita ainda são escassas na literatura. O objetivo do trabalho foi avaliar inclusões crescentes (0, 25, 50, 75 e 100% dos sólidos totais (ST) de capim elefante (Pennisetum purpureum Schum.) colhido em duas idades de corte mediana (MA) aos 45 dias de crescimento e avançada (AA) aos 90 dias, empregado em co-digestão com o dejeto suíno, adotando-se delineamento inteiramente ao acaso, em esquema fatorial 5x2. Foram utilizados biodigestores batelada de bancada, sendo as produções de biogás acompanhadas durante 12 semanas. Houve influência da idade da forragem (P<0,05) na degradação de sólidos e fibra em detergente neutro, com maiores valores para os substratos que continham a forragem MA. Os maiores rendimentos de CH4 foram alcançados pelos substratos que continham forragem MA na inclusão de 27,7 e 31,6 %, sendo de 253,7 e 222,2 L de CH4 por Kg de ST ou sólido volátil adicionado. A idade das forragens influenciou o início e a persistência das produções de biogás ao longo do período de digestão, sendo vantajosa apenas na inclusão de 25% de forragem com MA.

Dried distiller's grains plus solubles supplementation improves low-quality tropical grass utilization on beef steers / Suplementação de grãos de destilação secos com solúveis melhora a utilização de grama tropical de baixa qualidade para novilhos de corte

This study was designed to evaluate the effect of corn dried distiller's grains (DDGS) supplementation on feed intake, total tract digestibility, and ruminal fermentation of beef steers fed low-quality Guinea grass (Megathyrsus maximus, cv. Gatton panic). Twelve Braford crossbred steers were housed in individual pens (n = 4 steers/treatment), provided with three levels of DDGS supplement: 0%, 0.6%, or 1.2% BW. Steers were blocked by live weight and randomly assigned to treatments within the block. Corn DDGS supplementation increased total OM intake (21.55, 40.23, and 56.69 g/kg BW0.75) and tract OM digestibility (46.33, 49.03, and 72.39 % DM). Total tract digestible OM, CP, NDF and EE intake also increase in response to DDGS supplementation. Forage OM intake decreased when supplementation level reached 1.2 % BW. Also, ruminal pH decreased with DDGS supplementation level (6.88, 6.47, and 6.27). No differences were observed in total volatile fatty acids (VFA) concentration; however, the molar proportion of acetate decreased (77.98, 73.90, and 67.29 % Total VFA) as well as acetate: propionate ratio (4.38, 3.48, and 2.74). On the contrary, propionate proportions increased (18.32, 21.86, and 24.81 % Total VFA). Levels of ammonia and lactate were within suggested values for optimal fermentation and bacterial growth. Low-quality grass supplementation with corn DDGS increased total OM intake and digestibility. Also, DDGS inclusion favorably altered volatile fatty acids profile by reducing the acetate to propionate ratio regarding forage-only diets.

O objetivo deste estudo foi avaliar o efeito da suplementação com grãos de destilação secos de milho com solúveis (DDGS) no consumo, digestão e fermentação ruminal de novilhos de corte alimentados com capim-da-índia de baixa qualidade (Megathyrsus maximus, cv. Gatton panic). Doze novilhos mestiços Braford foram alojados em baias individuais (n = 4 novilhos / tratamento), fornecidos com três níveis de suplemento de DDGS: 0%, 0,6% ou 1,2% PV. Os novilhos foram bloqueados pelo peso vivo e atribuídos aleatoriamente aos tratamentos dentro do bloco. A suplementação com DDGS de milho aumentou o consumo de matéria orgânica total (21,55, 40,23 e 56,69 g / kg PV0,75), a digestibilidade da matéria orgânica (46,33, 49,03 e 72,39% MS) e o consumo de todos os nutrientes digestíveis. O consumo de matéria orgânica da forragem diminuiu quando o nível de suplementação atingiu 1,2% PV. Além disso, o pH ruminal diminuiu com o nível de suplementação com DDGS (6,88, 6,47 e 6,27). Não foram observadas diferenças na concentração de ácidos graxos voláteis totais, no entanto, a proporção molar de acetato diminuiu (77,98, 73,90 e 67,29% de AGV total), bem como a relação acetato: propionato (4,38, 3,48 e 2,74). Pelo contrário, as proporções de propionato aumentaram (18,32, 21,86 e 24,81% Total de AGV). Os níveis de amônia e lactato estavam dentro dos valores sugeridos para fermentação ideal e crescimento bacteriano. A suplementação de gramíneas de baixa qualidade com DDGS de milho aumentou o consumo e a digestibilidade da MO total. Além disso, a inclusão de DDGS alterou favoravelmente o perfil de ácidos graxos voláteis, reduzindo a proporção de acetato para propionato em relação às dietas apenas com forragem.