Navegando por Assunto "Brachiaria brizantha"

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Acesso aberto (Open Access)
Atividade alelopática de substâncias químicas isoladas do Capim-Marandu e suas variações em função do pH
(2008) SANTOS, Lourivaldo da Silva; SANTOS, Josiane Cristina Lucas dos; SOUZA FILHO, Antonio Pedro da Silva; CORRÊA, Marivaldo José Costa; VEIGA, Thiago Andre Moura; FERREIRA, Vivianne Cristinne Marinho Freitas; FERREIRA, Isabel Cristina Serrão; GONÇALVES, Nelson Santos; SILVA, Carlos E. da; GUILHON, Giselle Maria Skelding Pinheiro
This work aimed to isolate, identify and determine the allelopathic activity of the chemical substances produced by Brachiaria brizantha cv. Marandu and to verify the effects of the pH in the solution on the activity of these compounds. The allelopathic activity was evaluated based on germination bioassays and radicle and hypocotyl growth using the species 'malícia' (Mimosa pudica) and 'mata-pasto' (Senna obtusifolia) as receptors. The effect of pH was analyzed in a range from 3.0 to 9.0. The pentacyclic triterpenes friedelin and epifriefelinol isolated from the shoots of B. brizantha showed a low inhibitory activity against seed germination and radicle and hypocotyl growth of the two receptor plants evaluated. The pentacyclic triterpenes friedelin and epifrifelinol presented differentiated behaviors in relation to the pH variation in the solution, with stronger inhibition activity against the weed 'mata-pasto'.
Acesso aberto (Open Access)
Avaliação do ganho de peso e aspectos reprodutivos de primíparas zebuínas suplementadas com uréia no período seco
(Universidade Federal do Pará, 2009) CARDOSO, Robson Pinto; FATURI, Cristian; http://lattes.cnpq.br/8389692203753236
This study aimed to evaluate the productive and reproductive performance of cow cutting, supplemented with urea in the dry season. We used 58 females Tabapuã x Nellore crossbred, pregnant, with a mean age of 39 months and average weight of 399 kg. The worm and experimental animals were divided into two groups, in an area of 50 ha of grass Brachiaria brizantha cv Marandu, with 25 ha for each group, one group (A) supplemented with mineral and another (B) with mineral enriched with urea, the ratio of 80:20 (salt: urea). During the months of August-November, when most of the year in the dry, the grass had on average 5,800 kg of dry matter per hectare to 6.2% crude protein. These mixtures were administered in mineral cochos covered in order to meet ad libitum consumption during the dry period. The experimental design was completely randomized to two treatments. Difference was observed for final body weight (PVF) between the treatment with salt and mineral supplementation with urea, with average values of 360.1 kg and 385.8 kg, respectively. Difference was also observed for average daily gain, with an average of 0.465 kg/an/day for the treated group and 0.284 kg/an/day for the control group, postpartum with a gain of 41.2 and 26.5 kg/animal, respectively. The best performance of the supplemented animals should be related to the increase in dry matter intake promoted by supplementation with urea (12.610 kg to 8.744 kg). The best body growth (weight and body score) to the beginning of the amounts reflected in the expression of heat these animals, whereas 75% of cows supplemented with urea had expressed estrus during the first 60 days from the amounts to only 53, 33% of nonsupplemented. When we evaluated the whole period from the mount was not observed difference between the expression of estrus in females supplemented or not, a fact related to good body score submitted by the end of the animal to mount, 3.7 in females supplemented and 2, 9 in non-supplemented.
Acesso aberto (Open Access)
Banco de sementes de plantas daninhas em solo cultivado com pastagens de Brachiaria brizantha e Brachiaria humidicola de diferentes idades
(2001-08) SILVA, Débora Soraya Martins da; DIAS FILHO, Moacyr Bernardino
The objective of this work was to study the soil seed bank of a four-year-old Brachiaria brizantha pasture soil, and in pasture soils of four, 15 and 20 year–old Brachiaria humidicola, in northeastern Pará, Brazil, to evaluate the influence of the forage species and pasture age on weed seed bank size and composition. Each pasture area was divided into five plots of about 500 m², from which 10 soil sub-samples were collected at a depth of 0-10 cm. The soil from each plot was mixed, identified, placed in plastic trays, and put to germinate in a greenhouse during a 15-month period. The seed bank of the four-year-old B. brizantha pasture soil was about 10 times smaller than that in the four-year-old B. humidicola pasture. Among the B. humidicola pasture, the effect of pasture age showed that the weed seed bank was smaller in the 20-year-old pasture (1,247 seeds m-2). No significant difference could be detected between the 15- (11602 seeds m-2) and the four-year-old (9486 seeds m -2) pastures. The botanical families Cyperaceae, Rubiaceae and Labiateae were the most predominant among the weeds infesting all studied treatments.
Acesso aberto (Open Access)
Carbon content in Amazonian Oxisols after forest conversion to pasture
(2009-12) SILVA JÚNIOR, Mário Lopes da; DESJARDINS, Thierry; SARRAZIN, Max; MELO, Vânia Silva de; MARTINS, Paulo Fernando da Silva; SANTOS, Elaine Rodrigues; CARVALHO, Claudio Jose Reis de
Soil plays an important role in the C cycle, and substitution of tropical forest by cultivated land affects C dynamic and stock. This study was developed in an area of expansion of human settlement in the Eastern Amazon, in Itupiranga, State of Pará, to evaluate the effects of native forest conversion to Brachiaria brizantha pasture on C contents of a dystrophic Oxisol. Soil samples were collected in areas of native forest (NF), of 8 to 10 year old secondary forest (SF), 1 to 2 year old SF (P1–2), 5 to 7 year old SF (P5–7), and of 10 to 12 year old SF (P10–12), and from under pastures, in the layers 0–2, 2–5 and 5–10 cm, to evaluate C levels and stocks and carry out separation of OM based on particle size. After deforestation, soil density increased to a depth of 5 cm, with greater increase in older pastures. Variation in C levels was greatest in the top soil layer; C contents increased with increasing pasture age. In the layers 2–5 and 5–10 cm, C content proved to be stable for the types of plant cover evaluated. Highest C concentrations were found in the silt fraction; however, C contents were highest in the clay fraction, independent of the plant cover. An increase in C associated with the sand fraction in the form of little decomposed organic residues was observed in pastures, confirming greater sensitivity of this fraction to change in soil use.
Acesso aberto (Open Access)
Perfil da nutrição mineral dos rebanhos leiteiros, na microrregião de Castanhal e no município de Uruará, Estado do Pará
(Universidade Federal do Pará, 2002-12-10) MANESCHY, Rosana Quaresma; CARDOSO, Elyzabeth da Cruz; http://lattes.cnpq.br/8805703740727765
This study is part of a research project entitled “Sustentability of milk cattle production into the agriculture family systems in the Amazon eastern region” developed by Embrapa with objective to evaluate problems envolving small and medium farms in the micro-region of Castanhal (local 1) and in the county of Uruará (local 2), State of Para, Brazil. The objectives of this research were define the features and effected the mineral supplementation, analyze the mineral content of forage (Brachiaria brizantha cv. Marandu) planted in two different regions during the dry and rainy season of the year and identified the practical factors of restriction of mineral nutrition management used by farmers. There were developed two studies, in the first were study the localities using the questionnaire/interview methodology when defined the features that define the mineral supplementation used in the both locals. The dates gotten by questionnaire/interview permited obtain twenty-two important variables that were grouped in four main groups to characterize the practical management of mineral supplementation used in the two different locals. There was used descriptive statistic and the Qui-square test at 5% of probability for determination of the degree of significance when the different locals variables were compared. In the second study the pastures (Brachiaria brizantha cv. Marandu) in two locals samples of forage were harvested in two different periods of the year, end of dry season (November of 1998) and end of rainy season (June of 1999) with objective to analyses the calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K), cupper (Cu), zinc (Zn), iron (Fe), manganese (Mg) and cobalt (Co). A casual randomized design was used to compare the regions (local 1 and local 2) and for seasons (dry and rainy) was used a sub-plots design. The variance analyses was carried by the method of minimum square and the test of Fisher (F) was used to obtain the significance considering 5% as probability of effect. The Tukey’s test was used to compared the medium values. That was observed for both properties a high cost of mineral mixture used by farmers and this means an important significance in the economic costs for cows during the lactation period. In the local 1, Brachiaria brizantha cv. Marandu did not attempt the P, Na, Cu and Zn requirements for dairy cows during the lactation period and this is an indicative to procedure the mineral supplementation in a mineral feeder. The milk production is important for the economy of this region and farmers have problems to understand how in important supply different mineral mixtures for animals in different stages of production. Particularly in this micro-region was observed low concentration of P in the forage during the rainy season and this observation disagree from the other experiments concluded in this region, and can be an important problem during this period when the forage is more available and the level of protein and energy in the animal diet is high than an more intensive P imbalance can be present and this evidence is one more important feature responsible for low productivity of livestock. In the local 2, Brachiaria brizantha cv. Marandu did not attempt the P, Na and Cu requirements proposed by NRC (1996) for beef cattle, cows during the lactation period what indicated the importance to procedure the mineral supplementation in a mineral feeder. In this region was observed a low intake of mineral supplement and the condition of mineral feeder was neglected. The location of mineral feeder inside the enclosure, the limitation of animal access permited only during the milking activities were problems that indicated the reason to low intake of mineral supplement by cows. It was indicated a change of this management for one system that provide the mineral supplementation as the cows requirement. The main anormality frequency observed was abnormal appetite that was characterized when another problems were related which ould be characterized in reproduction problems, loss of appetite, bone abnormalities, and low body weight of the animals. These problems were more intensive when clinical deficiency of P and Cu were suggested.