https://www.alice.cnptia.embrapa.br/alice/handle/item/160 Artigo em periódico indexado (CNPGC) 2026-08-15T23:12:43Z https://www.alice.cnptia.embrapa.br/alice/handle/doc/1187743 Título: Alterações clínicas, patológicos e laboratoriais na intoxicação crônica por cobre em ovinos. Autoria: LEMOS, R. A. A.; RANGEL, J. M. R.; OSORIO, A. L. A. R.; MORAES, S. D. S.; NAKAZATO, L.; SALVADOR, S. C.; MARTINS, S. Conteúdo: Resumo: Com o objetivo de avaliar a toxicidade do cobre em ovinos, administrou-se sulfato de cobre a quatro grupos, nas dosagens de 15, 30, 60 e 120ppm, até surgirem os sinais da intoxicação; um quinto grupo permaneceu como controle. Estes animais foram submetidos a exames clínicos diários e a determinações periódicas dos níveis séricos de trasaminase glutâmico oxalacética (AST) e gamaglutamiltransferase (gGT). Aqueles que morreram durante o experimento foram necropsiados, sendo os fragmentos dos principais órgãos analisados histologicamente; adicionalmente foram determinados os níveis de cobre hepático. Em todos os grupos houve casos de intoxicação, os quais ocorreram entre 80 e 116 dias. Os principais sinais clínicos da intoxicação foram: depressão, icterícia, hemoglobinúria e diarréia. Elevações dos níveis de gGT e AST foram observadas entre 21 e 43 dias antes do aparecimento dos sinais clínicos, atingindo valor máximo durante o quadro clínico. As principais alterações histológicas foram observadas no fígado e rins, revelando lesões degenerativas. Os valores de cobre hepático variaram entre 1097,5 e 1366,9ppm, evidenciando níveis iguais ou superiorres a duas vezes o valor considerado como limite máximo normal, confirmando-se assim que este elemento foi responsável pelo quadro clínico patológico. Todas as dosagens usadas no experimento foram consideradas como potencialmente tóxicas para esta espécie animal. Abstract: In order to evaluate the copper toxicity in sheep, 4 groups of animals have been administered Copper sulfate at the dosagens 15, 30, 60 and 120ppm, until signs of intoxication occurred. There was still a 5th group, as control. These animals have been submitted to daily physical examination and periodical determinations of AST and gGT serum levels. Those that have died during the study have been necropsied and the fragments of the main organs have been histologically examined. The liver copper levels have also been determined. In all groups there have been cases of intoxication, which occurred between the 80th and 116th day. The principal clinical signs of intoxication were: depression, jaundice, haemoglobinuria and diarrhea. It has been observed raised levels of gGT and AST between 21st and 43rd day before the clinical signs appeared, getting the maximum value during the clinical stage. The main histological changes were present in the liver and kidneys, showing degeneration lesions. Lever copper values varied from 1097.5 is 1366.9ppm, showing the same level or twice the value considered to be the maximum normal limit, assuring thus that this element has been responsible for the pathological clinical process. All the dosagens used in the study have been considered potentially toxic to this species. 1997-01-01T00:00:00Z https://www.alice.cnptia.embrapa.br/alice/handle/doc/1187650 Título: Effects of nitrogen fertilization on forage production, animal performance, and greenhouse gas emissions in tropical pastures: a systematic review. Autoria: SILVA, H. R. da; DIFANTE, G. dos S.; ROBERTO, F. F. da S.; FERREIRA JUNIOR, M. A.; ARAÚJO, C. M. C.; LONGHINI, V. Z.; RODRIGUES, J. G.; PEREIRA, M. de G.; MONTAGNER, D. B.; ÍTAVO, L. C. V.; GURGEL, A. L. C.; CASTRO, M. M. P. M. F. de Conteúdo: ABSTRACT - This systematic review aimed to synthesize evidence on the effects of nitrogen (N) fertilization on forage production, animal performance, and greenhouse gas emissions in tropical pastures. The research question was developed based on the PICOS strategy. A total of 84,629 documents were retrieved from six databases, of which 34 studies met the inclusion criteria due to their methodological robustness. Most studies were conducted under grazing conditions (69.7%), using Brachiaria brizantha (52.9%) and Panicum maximum (26.5%). Urea (53.2%) and ammonium nitrate (25.5%) were the most evaluated N sources, with application rates ranging from 0 to 1000 kg ha⁻¹ , often split into three applications. Nitrogen use increased stocking rate (157.7%), gain per area (189.4%), and average daily gain (31.0%) when application rates rose from 0 to 300 kg ha⁻¹ . Overall, N fertilization has potential to improve forage productivity and animal performance in tropical pastures; however, responses vary depending on rates, sources, and experimental conditions. Splitting N rates (20–60 kg ha⁻¹) and synchronizing applications with plant demand are effective strategies to reduce NH₃ and N₂O losses, enhance fertilizer use efficiency, and mitigate environmental impacts. Future research should focus on evaluating the effects of different N sources and doses on soil CO₂ and CH₄ emissions, enteric CH₄, and C/N dynamics within the soil–plant–animal system, as well as expanding studies to other forage and animal species representative of tropical grazing systems. 2026-01-01T00:00:00Z https://www.alice.cnptia.embrapa.br/alice/handle/doc/1187658 Título: Potassium fertilization reduces the severity of leaf spot complex and mosaic in Megathyrsus maximus cultivars. Autoria: VÉRAS, E. L. de L.; DIFANTE, G. dos S.; MONTAGNER, D. B.; ARAUJO, A. R. de; MACEDO, M. C. M.; THEODORO, G. de F.; ARAÚJO, C. M. C.; GURGEL, A. L. C.; MONTEIRO, G. O. de A.; RODRIGUES, J. G.; PEREIRA, M. de G.; SANTANA, J. C. S. Conteúdo: ABSTRACT - The objective of this study was to evaluate the effects of potassium (K) on disease severity and the chemical composition of Megathyrsus maximus cultivars. The experiment was conducted in a randomized block design in a 6 × 4 factorial arrangement, consisting of six Megathyrsus maximus cultivars (Massai, Mombaça, Tamani, Tanzânia, Quênia, and Zuri) and four K doses (0, 205, 410, and 820 mg dm−3 ). The severity of the leaf spot complex, caused by Bipolaris maydis and B. yamadae, was assessed using a diagrammatic scale. A significant interaction between K doses and cultivars was observed for all evaluated diseases. At K doses of 0 and 205 mg dm−3 , the Tanzânia cultivar showed lower leaf spot severity compared with the other cultivars, whereas at higher doses, no disease symptoms were observed in any cultivar. The area under the disease progress curve (AUDPC) for mosaic followed a linear model only for the Tanzânia cultivar, whereas quadratic regression models best described the response for the remaining cultivars, with maximum mosaic severity values of 67.74% for Quênia, 72.34% for Mombaça, 76.99% for Zuri, 74.88% for Massai, and 68.93% for Tamani. Increasing K doses reduced the severity of both the leaf spot complex and mosaic. However, the leaf spot complex did not affect the nutritional value of the evaluated cultivars. 2026-01-01T00:00:00Z https://www.alice.cnptia.embrapa.br/alice/handle/doc/1187636 Título: Tillering dynamics and morphogenesis in BRS Zuri Guinea grass pastures: responses to grazing management. Autoria: RODRIGUES, J. G.; DIFANTE, G. dos S.; MONTAGNER, D. B.; PEREIRA, M. de G.; EUCLIDES, V. P. B.; ARAUJO, A. R. de; MONTEIRO, G. O. de A.; SANTANA, J. C. S.; ÍTAVO, L. C. V.; SBRÍSSIA, A. F. Conteúdo: ABSTRACT - Studies on morphogenesis and tillering are crucial for pasture productivity and sustainability, as forage production depends on tiller performance and population density. This two-year study assessed the impact of four grazing frequencies on tillering dynamics and morphogenesis traits of Megathyrsus maximus cv. BRS Zuri under intermittent stocking. A randomized block design was employed, with four pre-grazing light interception (LI) levels (80%, 85%, 90%, and 95%) and four replications per treatment. Evaluated variables included leaf appearance (LAR), elongation (LER) and senescence rates (LSR), leaf lifespan (LLS), phyllochron (PHYL), final leaf length (FLL), live leaf number (LLN), stem elongation rate (SER), tiller appearance (TAR), mortality (TMR) and survival rates, tiller stability index (TSI), and forage accumulation rate (FAR). There was an effect of LI on PHYL, LER, SER, LLS, and LSR, where data fit increasing linear regressions, with increments of 0.29 days, 2.86 cm, 0.013 cm, 1.52 days, and 0.058 cm, respectively, as LI increased. Tiller appearance was similar across treatments, whereas mortality and survival rates showed LI × year interaction. The highest mortality rate was observed in pastures managed with 80% LI, while the lowest mortality and highest survival rates occurred in those managed with 95% LI. TSI increased with LI and was higher in the first year, with reductions under 80% and 85% LI. Pastures managed at 90% and 95% LI showed more stable tiller populations and greater leaf elongation and FLL. Management with 90% LI allows for growth interruption before the greatest pseudostem accumulation and leaf senescence. 2026-01-01T00:00:00Z