Jenynsia lineata species complex, revision and new species description (Cyprinodontiformes: Anablepidae).

The Jenynsia lineata species complex comprises J. lineata from Montevideo, Uruguay and Jenynsia multidentata, from coastal basins of Brazil, Uruguay and Argentina up to 1200 m a.s.l. Taxonomic divisions within this group were tested using three different species delimitation methods, which found the two existing names to be synonyms and revealed a new cryptic species. Jenynsia darwini sp. nov. is distinguished from all congeners by having a unique combination of character states, including the shape of the dorsal postcleithrum (three times higher than wide v. less than two times higher than wide) and female colour pattern in the half of the caudal peduncle with rows of chromatophores segmented in unaligned spots (v. aligned spots forming lines). The new species also differs from J. lineata by having 26 nucleotide substitutions in the mitochondrial gene cytochrome c oxidase I (coI). Phylogenetic analysis of the genus based on morphological characters proposed by previous studies corroborates monophyly of the subgenera Plesiojenynsia and Jenynsia, with the new species being allocated to the subgenus Jenynsia as the sister group of J. lineata.

Neostigmine vs. sugammadex: observational cohort study comparing the quality of recovery using the Postoperative Quality Recovery Scale.

BACKGROUND: Quality of postoperative recovery is an important outcome after surgery. An observational cohort study was designed to assess the quality of postoperative recovery using the Portuguese version of the Postoperative Quality Recovery Scale (PQRS) in patients treated with neostigmine vs. sugammadex as neuromuscular blocking reversal agents. METHODS: A convenience sample of 101 adult patients undergoing elective surgery with general anaesthesia and treated with neostigmine (n=48) or sugammadex (n=53) as neuromuscular blocking reversal agents was included. Patients were evaluated using the Portuguese PQRS version at baseline and postoperatively at 15 (T15) and 40 (T40) min and also at days 1 and 3. Recovery was defined as return to baseline values (or better) at each time points. RESULTS: The PQRS overall recovery rates were similar in both groups, but recoveries in the nociceptive (96.2% vs. 81.3%, P=0.02) and physiological (96.2% vs. 70.2%, P=0.001) domains at T40 were higher in the sugammadex group than in the neostigmine group. Also, there was a trend that patients treated with sugammadex reported significantly better global perspective on the impact of surgery on working capacity and daily activities, as well as higher satisfaction with anaesthetic care. CONCLUSIONS: This pilot study suggests that sugammadex may improve physiological and nociceptive postoperative recovery as well as patient satisfaction with anaesthetic care. Although we lack an explanation for a possible favourable impact of sugammadex on quality of recovery, our results may provide sufficient preliminary data to justify a randomised trial to explore this possibility.

Agronomic parameters of sugarcane under planting densities in different cultivation cycles.

Low density sugarcane plantation (LDSP) has been implemented by some sugarcane producers in Brazil, aiming to save seeds and operational costs. The study was carried out in the municipality of Areia, Paraíba, Brazil. Five planting densities were used, varying from 5 to 25 m-2 of buds arranged in randomized blocks, with four replications. Data were measured annually over three cultivation cycles (2017 to 2020), during which the field was fertilized with NPK and the harvests were carried out manually without prior burning. The lower planting density presents higher productivity only in the cane plant (101.03 t ha-1) due to the higher plant height (2.37 m) and the higher number of stalks (11 stalks m-2), suggesting that these variables are due to the greater availability of light, water and photosynthate. However, there is a drastic reduction in sugarcane yield for this lower population in the 2nd ratoon by up to 65.62%, which is correlated with number of stalks per meter. We demonstrate the agronomic viability of LDSP in the population of 10 buds m-2 in relation to conventional planting of sugarcane until the 2nd ratoon. Data are important for future studies to present additional considerations for other production factors, such as the effects of mechanized harvesting and the management of nutrients and water, assessing the sustainability of this large-scale planting system.

Differences between FEV6, FVC and VC at the diagnosis of obstructive ventilatory defect.

INTRODUCTION: The diagnosis of airway obstruction can be made through FEV1/FVC ratio <0.7 or FEV1/VC ratio < lower limit of normality (LLN). Several authors advocate that FEV1/FEV6 ratio is an alternative to diagnosing obstructive ventilatory defect, while others have determined that the best cut-off for this ratio (best combined sensitivity and specificity) is 0.73. OBJECTIVE: To evaluate the non-inferiority of FEV1/FEV6 ratio < 0.73 when compared to FEV1/FVC ratio < 0.7 and FEV1/VC < LLN in diagnosing airway obstruction. METHODS: A retrospective analysis of the medical records from patients who underwent spirometry or plethysmography in a university central hospital from June 1st to December 31st, 2018 was carried out. Only medical records which included FEV1/FVC < 0.7 or FEV1/VC < LLN were selected, and these results were compared to FEV1/FEV6 ratio. RESULTS: A total of 526 patients with obstructive ventilatory defect were identified by one of the two ratios described. Of these, 95.1%, 87.4% and 88.6% were obstructive by FEV1/FVC, FEV1/VC, and FEV1/FEV6 ratio, respectively. The positive predictive value (PPV) of FEV1/FEV6 in relation to FEV1/FVC ratio was 99.6% (p < 0.001) with a diagnostic efficacy of 92.8%, whereas the PPV of FEV1/FEV6 in relation to FEV1/VC was 91.0% (p < 0.001) and diagnostic efficacy was 85.2%. Most false negatives, comparing FEV6 with the other two tests, were found in patients with FEV1 > 70% (mild obstruction) and in individuals aged >50 years. CONCLUSIONS: FEV1/FEV6 < 0.73 may be a good alternative ratio, as it is non-inferior to FEV1/VC and FEV1/FVC in diagnosing obstructive ventilatory defect.

Anti-Candida activity of the water-soluble lectin from Moringa oleifera seeds (WSMoL).

This work reports the effects of the water-soluble lectin from Moringa oleifera seeds (WSMoL) on growth and survival of Candida species. In addition, cellular alterations linked to the antifungal effect were investigated. The minimal inhibitory (MIC) and fungicidal (MFC) concentrations were determined and 24-h growth curves in absence and presence of lectin were established. Flow cytometry was used to evaluate the induction of apoptosis/necrosis, alterations in mitochondrial membrane potential (ΔΨm), and occurrence of lysosomal damage. WSMoL inhibited the growth of C. albicans, C. glabrata, C. krusei and C. parapsilosis with MIC of 20µg/mL. The lowest MFC (20µg/mL) was detected for C. glabrata and the highest (80µg/mL) for C. albicans and C. parapsilosis. The inhibitory effect started from the ninth to nineteenth hour of incubation depending on the fungal species. Incubation with the lectin at the MIC for 24h increased the number of cells undergoing apoptosis and necrosis. Hyperpolarization of the mitochondrial membrane was detected after 12-h treatment, followed by reduction of ΔΨm or depolarization after 24h. No lysosomal damage was detected in treated cells. In conclusion, WSMoL is a fungistatic and fungicide agent against Candida with differential effects depending on the species.

Do we have today a reliable method to detect the moment of loss of consciousness during induction of general anaesthesia? / ¿Contamos actualmente con un método fiable para detectar el momento de pérdida de consciencia durante la inducción de la anestesia?

This review aims to give an overview of the current state of monitoring depth of anaesthesia and detecting the moment of loss of consciousness, from the first clinical signs involved in anaesthesia to the latest technologies used in this area. Such techniques are extremely important for the development of automatic systems for anaesthesia control, including preventing intraoperative awareness episodes and overdoses. A search in the databases Pubmed and IEEE Xplore was performed using terms such anaesthetic monitoring, depth of anaesthesia, loss of consciousness, as well as anaesthesia indexes, namely BIS. Despite the several methods capable of monitoring the hypnotic state of anaesthesia, there is still no methodology to accurate detect the moment of loss of consciousness during induction of general anaesthesia.

Reliability of Cardiorespiratory and Metabolic Responses During Incremental Shuttle Walk Test in Adult Subjects With Asthma.

BACKGROUND: The incremental shuttle walk test (ISWT) has been widely used to assess exercise capacity of subjects with COPD. However, to date, no studies have assessed its reliability in the asthmatic population. This study aimed to assess the test-retest reliability of ISWT for the distance walked (ISWD) and cardiorespiratory and metabolic responses in adult subjects with asthma. METHODS: This was a cross-sectional observational study. Thirty-four subjects of both genders, 18-45 y old, with a diagnosis of controlled asthma, were recruited from March 2012 to December 2015. The subjects performed 3 ISWTs on different days, with a minimum interval of 48 h and a maximum of 1 week between the second and third ISWT. For the reliability analysis, the values of the second and third ISWTs were used, eliminating the influence of any learning effect from the first test. RESULTS: The intraclass correlation coefficients were > 0.75 (P < .001) for ISWD (m), speed (km/h),oxygen uptake (V̇O2 ), ventilatory equivalent carbon dioxide (V̇E/V̇CO2 ), and minute ventilation (V̇E) at the ISWT peak. The Bland-Altman plot presented a mean error close to zero, and measurement distribution was within acceptable limits of variation. CONCLUSION: The ISWT presented excellent reliability for the ISWD and metabolic responses. The cardiorespiratory responses in the ISWTs presented good reliability. We concluded that the ISWT was reliable for young adult subjects with controlled asthma.

Soil chemical factors and grassland species density in Emas National Park (central Brazil).

Studies of grasslands on specific soil types suggest that different nutrients can limit biomass production and, hence, species composition and number. The Brazilian cerrado is the major savanna region in America and once covered about 2 million km(2), mainly in the Brazilian Central Plateau, under seasonal climate, with wet summer and dry winter. In view of the importance of soil chemical factors in the distribution of the vegetation forms within the Cerrado domain and which may influence the number of species, we analyzed some soil characteristics in three herbaceous vegetation forms -- hyperseasonal cerrado, seasonal cerrado, and wet grassland -- in Emas National Park, a core cerrado site, to investigate the relationship between number of species and soil characteristics. We collected vegetation and soil samples in these three vegetation forms and submitted the obtained data to multiple linear regression. We found out that aluminum and pH were the best predictors of species density, the former positively related to species density and the latter negatively related. Since the predictable variation in species density is important in determining areas of conservation, we can postulate that these two soil factors are indicators of high species density areas in tropical grasslands, which could be used in selecting priority sites for conservation.

Study of major genetic factors involved in pituitary tumorigenesis and their impact on clinical and biological characteristics of sporadic somatotropinomas and non-functioning pituitary adenomas.

Genetic and functional aberrations of guanine nucleotide-binding protein, alpha stimulating (GNAS), aryl hydrocarbon receptor interacting protein (AIP), and pituitary tumor transforming gene (PTTG) are among the most prominent events in pituitary tumorigenesis. A cohort of Brazilian patients with somatotropinomas (n=41) and non-functioning pituitary adenomas (NFPA, n=21) from a single tertiary-referral center were evaluated for GNAS and AIP mutations and gene expression of AIP and PTTG. Results were compared to the clinical and biological (Ki67 and p53 expression) characteristics of tumors and their response to therapy, if applicable. Genetic analysis revealed that 27% of somatotropinomas and 4.8% of NFPA harbored GNAS mutations (P=0.05). However, no differences were observed in clinical characteristics, tumor extension, response to somatostatin analog therapy, hormonal/surgical remission rates, Ki67 index, and p53 expression between mutated and non-mutated somatotropinomas patients. PTTG overexpression (RQ mean=10.6, min=4.39, max=11.9) and AIP underexpression (RQ mean=0.56, min=0.46-max=0.92) were found in virtually all cases without a statistically significant relationship with clinical and biological tumor features. No patients exhibited somatic or germline pathogenic AIP mutations. In conclusion, mutations in GNAS and abnormal PTTG and AIP expression had no impact on tumor features and treatment outcomes in this cohort. Our data support some previous studies and point to the need for further investigations, probably involving epigenetic and transcriptome analysis, to improve our understanding of pituitary tumor behavior.

Time resolved measurements by the pulse height analysis soft x-ray diagnostic on TCV.

A single chord, single processing chain, hybrid (analog/digital) pulse height analysis diagnostic has been developed for the TCV tokamak, aiming to provide the evolution of the plasma electron temperature with a software selectable minimum temporal resolution of 100 ms. The high count rate (approximately 65 kHz) together with an energy resolution of 190 eV (at 5.9 keV) were achieved by encoding the data stream with an on-site developed interface amplifier and time generator. The diagnostic was also used to investigate the non-Maxwellian behavior of the electron energy distribution function with strong electron cyclotron resonance heating and to monitor the presence of intrinsic and injected impurities in the 700 eV-20 keV energy range. The conversion of this diagnostic into a real-time control tool is under development.

Practical aspects of the use of target controlled infusion with remifentanil in neurosurgical patients: predicted cerebral concentrations at intubation, incision and extubation.

Remifentanil has important side effects and it is not easy to know what remifentanil concentrations should be used during different endpoints of anaesthesia. We analyzed the remifentanil predicted effect-site concentrations (RemiCe) at different events during neurosurgical procedures and assessed if the concentrations used were clinically adequate. BIS and haemodynamic parameters were collected every 5 seconds. Predicted cerebral concentration of propofol (PropCe) and RemiCe were analyzed immediately prior to respective stimulus, and 30, 60 and 90 seconds after. RemiCe were 2.2 +/- 0.3, 6 +/- 2.6 and 2.2 +/- 0.9 ng ml(-1) at intubation, incision and extubation, respectively. PropCe observed in the same periods were 5 +/- 1, 2.6 +/- 0.9 and 1 +/- 0.3 microg ml(-1), also respectively. The remifentanil concentrations used in our patients were lower than reported concentrations, while being clinically adequate to minimize the haemodynamic response to stimulation.

Soil characteristics of a hyperseasonal cerrado compared to a seasonal cerrado and a floodplain grassland: implications for plant community structure.

Savannas may be divided according to their seasonality into semi-seasonal, seasonal, hyperseasonal, or marshy savannas. Hyperseasonal savannas are characterized by the alternation of two contrasting stresses during each annual cycle, one induced by drought and fire and the other, by waterlogging. In South America, the largest savanna region is the Brazilian cerrado, in which there are few hyperseasonal areas that become waterlogged in the rainy season. The cerrado soils are generally well drained, but in central Brazil there is a small cerrado area in which the soil is poorly drained and which becomes waterlogged in the middle of the rainy season, allowing the appearance of a hyperseasonal cerrado. As long as soil is important in the ecology of the cerrado vegetation, we asked whether the waterlogging in this hyperseasonal cerrado implied that there were differences in soil characteristics in relation to a seasonal cerrado, which is not waterlogged in the rainy season, and to a floodplain grassland, which remains waterlogged throughout the year. In each environment, we randomly selected ten points, in which we collected soil samples in the mid-rainy season for chemical and granulometric analyses. For all variables, we found significant differences among the three environments, at least at one of the depths. Nevertheless, when we took into account all the variables together, we observed that the soils under the hyperseasonal and seasonal cerrados were similar and both were different to the soil under the floodplain grassland. The soil under the floodplain grassland was related to larger amounts of clay, silt, organic matter, phosphorus, aluminium, aluminium saturation, cation exchange capacity, and sum of bases, whereas soils under hyperseasonal and seasonal cerrados were related to higher pH values, base saturation, calcium, magnesium, and sand. As long as the soil under both cerrados was chemically and physically similar, the duration of waterlogging in the hyperseasonal cerrado is not long enough to alter its soil characteristics. Limitations to the plants growing on the hyperseasonal cerrado soil must be a consequence of the direct effects of flooding. Since cerrado plant species are dryland ones, the hypoxia caused by waterlogging may limit the number of cerrado species able to withstand these conditions.

[Hydroxyethyl starch 130/0.4 can be useful to prevent a hemodynamic response to a single dose of remifentanil]. / E1 hidroxietilalmidón (HES) 130/0.4 puede ser úitil en la prevención de la respuesta hemodinámica a un bolus de remifentanilo.

Intravenous propofol and remifentanil are often used in anesthesia. The combined use of these drugs tends to cause hemodynamic depression. We describe the absence of hemodynamic effects in response to infusion of propofol and remifentanil when hydroxyethyl starch (HES) 130/0.4 was also administered. During induction, because blood volume needed to be replaced, two patients aged 62 and 65 years received intravenous HES 130/0.4. They then received a single dose of 2 microg x kg(-1) of remifentanil during total intravenous anesthesia (TIVA) with propofol and remifentanil before placement of a Mayfield head holder. No changes in mean blood pressure or heart rate were observed in either patient after the remifentanil bolus when they have received HES 130/0.4 during TIVA with propofol and remifentanil HES 130/0.4 may play an active role in preventing a hemodynamic response to remifentanil bolus. This hypothesis should be tested in a randomized controlled trial.

The Mini-International Neuropsychiatric Interview (M.I.N.I.): the development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10.

The Mini-International Neuropsychiatric Interview (M.I.N.I.) is a short structured diagnostic interview, developed jointly by psychiatrists and clinicians in the United States and Europe, for DSM-IV and ICD-10 psychiatric disorders. With an administration time of approximately 15 minutes, it was designed to meet the need for a short but accurate structured psychiatric interview for multicenter clinical trials and epidemiology studies and to be used as a first step in outcome tracking in nonresearch clinical settings. The authors describe the development of the M.I.N.I. and its family of interviews: the M.I.N.I.-Screen, the M.I.N.I.-Plus, and the M.I.N.I.-Kid. They report on validation of the M.I.N.I. in relation to the Structured Clinical Interview for DSM-III-R, Patient Version, the Composite International Diagnostic Interview, and expert professional opinion, and they comment on potential applications for this interview.

Effect of small changes in temperature on CA1 pyramidal cells from rat hippocampal slices during hypoxia: implications about the mechanism of hypothermic protection against neuronal damage.

Small reductions in temperature have been shown to improve neurologic recovery after ischemia. We have examined the effect of temperature on biochemical and physiological changes during hypoxia using rat hippocampal slices as a model system. The postsynaptic population spike recorded from the CA1 pyramidal cell region of slices subjected to 7 min of hypoxia with hypothermia (34 degrees C) recovered to 73% of its prehypoxic level; slices subjected to the same period of hypoxia at 37 degrees C did not recover. After 7 min of hypoxia ATP fell to 48% of its prehypoxic concentration at 34 degrees C and 30% at 37 degrees C. Potassium fell to 86% during 7 min of hypoxia with hypothermia, this compares to a fall to 58% at 37 degrees C. The increase in sodium after 7 min of hypoxia was also attenuated by hypothermia (133% vs. 163% of its prehypoxic concentration). When the hypoxic period was shortened to 3 min (37 degrees C) the population spike recovered to 94%. If the temperature was increased to 40 degrees C there was only 7% recovery of the population spike after 3 min of hypoxia. With hyperthermia (40 degrees C), ATP fell to 33% after 3 min of hypoxia, this compares to 81% at normothermia. Potassium fell to 76% after 3 min of hypoxia with hyperthermia, this compares to 91% at 37 degrees C. Sodium concentrations increased with hyperthermia before hypoxia, at 3 min of hypoxia there was no significant difference between the hyperthermic and normothermic tissue; there was a large increase in sodium with hyperthermia after 5 min of hypoxia (209% vs. 146%). We conclude that the improved recovery after hypothermic hypoxia is at least in part due to the attenuated changes in ATP, potassium and sodium during hypoxia and that the worsened recovery with hyperthermia is due to an exacerbation of the change in ATP, potassium and sodium concentrations during hypoxia.

Anoxia reduces depolarization induced calcium uptake in the rat hippocampal slice.

Veratridine-induced depolarization caused a large increase in Ca uptake in the rat hippocampal slice (30.2 vs. 9.0 nM/mg dry weight). This uptake was reduced to 18.4 nM/mg when veratridine was combined with anoxia. When compared with veratridine exposure alone, the combination of anoxia and veratridine increased intracellular Na (460 vs. 380 microM/g), decreased intracellular K (30 vs. 40 microM/g) and decreased ATP levels (0.1 vs. 0.8 nM/mg). The changes in Na, K, and ATP should enhance net Ca uptake, yet Ca uptake was reduced. This suggests an effect of anoxia to block Ca channels. In summary anoxia attenuates depolarization-induced Ca uptake. This may represent a mechanism by which neurons are partially protected against anoxic damage which could be more severe if depolarization-induced Ca uptake was not limited.

The effect of isoflurane on biochemical changes during and electrophysiological recovery after anoxia in rat hippocampal slices.

It is unclear whether isoflurane protects against neuronal damage. This study examines the extent and mechanism by which isoflurane might affect anoxic neuronal damage. The size of the evoked postsynaptic population spike recorded from the CA 1 pyramidal cell layer of the rat hippocampal slice 60 min after anoxia was compared with its preanoxic, preisoflurane level. Intracellular adenosine triphosphate (ATP), sodium, and potassium levels were measured in the dentate and CA 1 regions at the end of the anoxic period in similarly treated slices. Isoflurane increased the latency and reduced the amplitude of the evoked response before anoxia. Isoflurane (2%) did not significantly improve recovery of the evoked response after 5 min of anoxia (untreated slices = 6 +/- 2% (mean +/- SEM), isoflurane = 17 +/- 7%); 1.5% isoflurane also did not significantly improve recovery after 4 min of anoxia (untreated = 30 +/- 8% vs. 1.5% isoflurane = 47 +/- 12%). Isoflurane did not significantly attenuate the decrease in ATP levels in either the dentate or CA 1 regions of the hippocampal slice during 4 or 7 min of anoxia; however, there was a significant improvement in ATP levels after 10 min of anoxia in both regions of isoflurane-treated preparations (1.0 +/- 0.1 vs. 1.4 +/- 0.1, CA 1; 1.3 +/- 0.1 vs. 2.0 +/- 0.2 nM/mg dry weight, dentate). Sodium concentrations increased and potassium concentrations decreased during anoxia. Isoflurane did not significantly attenuate the changes in these ions during anoxia. In conclusion, isoflurane does not significantly improve recovery of CA 1 pyramidal cells during anoxia nor does it attenuate the anoxic changes in ATP, sodium, and potassium after 4 or 7 min of anoxia. With a more prolonged period of anoxia (10 min) isoflurane reduces the decrease in ATP levels.

DSM-IH-R Psychotic Disorders: procedural validity of the Mini International Neuropsychiatric Interview (MINI). Concordance and causes for discordance with the CIDI.

OBJECTIVES: the Mini International Neuropsychiatric Interview (MINI) is a short diagnostic structured interview (DSI) designed to generate positive diagnosis for the main Diagnostic and Statistical Manual (DSM)-III-R/IV Axis I disorders and to explore the symptoms of Criterion A for Schizophrenia (Sc) to rule out the presence of Psychotic Disorders. The procedural validity of the MINI was investigated in psychiatric patients using the Composite International Diagnostic Interview (CIDI) as a gold standard in Europe and the Structured Clinical Interview for DSM-III-R (SCID-P)in the US. This paper presents the concordance and the reasons for discordance between the MINI and the CIDI for DSM-III-R Psychotic and Mood Disorders. No study had systematically analysed the sources of disagreement between DSI based on the same operational criteria in psychotic patients. METHODS: 256 consecutively recruited psychiatric patients and 50 non-psychiatric subjects passed the MINI and the CIDI. RESULTS: concordance was good for the presence of Major Depressive Episode (MDE), Manic Episode, Psychotic Disorders, syndromes or symptoms (0.65 to 0.82). Inconsistencies in evaluation of the disorder recency accounted for 25 to 40% of discordance for current diagnoses. Fifty-three percent of discordance for lifetime Manic Episode resulted from inconsistencies in the severity of the index episode. Fifty percent of discordance for the diagnosis of Psychotic Disorders was due to algorithmic differences between the two DSI. CONCLUSION: the MINI yields reliable DSM-III-R diagnoses within a short time frame (22 minutes). Depending on the quantitative and the qualitative analyses of discrepancies between the MINI and the CIDI for Psychotic Disorders and Mood Episodes, we proposed and tested modifications leading to improvements in both interviews. The procedural validity of the modified MINI according to the modified CIDI was found to be very good.

Beef cattle performance on signal grass pastures deferred and fertilized with nitrogen / Desempenho de bovinos em pastos de capim-braquiária diferidos e adubados com nitrogênio

The effect of four nitrogen levels (0, 40, 80 and 120kg N ha-1), applied before deferment on the beef cattle production and structural variables on Urochloa decumbens (signal grass) were assessed from January to October 2012 and from January to September 2013. A randomized block design with three replicates was adopted, in an arrangement of repeated measures in time (grazing period). An interaction effect between nitrogen level and grazing period was observed on extended-plant height and herbage mass. As the nitrogen levels were increased, extended-plant height, herbage mass, total herbage allowance, and efficiency of conversion of fertilizer into herbage were increased. Throughout the grazing period, pasture height, extended-plant height, percentage of leaves, herbage and morphological components allowance, and percentages of leaves and stems in the herbage apparently selected by the animal decreased. Nitrogen levels had no effect on average daily gain or gain per area in the first year. A fixed deferment period with increasing levels of nitrogen fertilization on signal grass pastures does not influence the average daily gain per animal, reduces the efficiency of the nitrogen fertilizer and negatively changes the structural characteristics of the pasture.(AU)

Foi avaliado o efeito de quatro doses de nitrogênio (0, 40, 80 e 120kg N ha -1 ), aplicadas antes do diferimento, sobre o desempenho de bovinos e as características estruturais de Urochloa decumbens (capim-braquiária), de janeiro a outubro de 2012 e de janeiro a setembro de 2013. Um delineamento de blocos ao acaso foi utilizado em arranjo de medidas repetidas no tempo (período de pastejo). Foi observada interação entre doses de nitrogênio e período de pastejo na altura da planta estendida e na massa de forragem. As doses de nitrogênio incrementaram a altura da planta estendida, a massa de forragem, a oferta de forragem e a eficiência de conversão do nitrogênio em forragem. No decorrer do período de pastejo, a altura do pasto, a altura da planta estendida, a porcentagem de lâminas foliares, a oferta de forragem e dos seus componentes morfológicos e a porcentagem de lâminas e colmos da forragem aparentemente selecionada pelos animais diminuíram. As doses de nitrogênio não exerceram efeito sobre o ganho diário e o ganho diário por área no primeiro ano. O período de diferimento fixo com aumento das doses de nitrogênio em pastos de capim-braquiária não influencia o ganho diário por animal, reduz a eficiência da adubação nitrogenada e afeta negativamente a estrutura do pasto.(AU)