RESUMO Objetivou-se avaliar os efeitos de quatro alturas (15, 25, 35 e 45cm) da Urochloa brizantha cv. Marandu (capim-marandu) no início do diferimento sobre a morfologia do pasto, a seletividade e o desempenho de ovinos no início, meio e fim do período de pastejo, no inverno. Foi utilizado o delineamento inteiramente ao acaso, com três repetições. Os pastos diferidos com 35 e 45cm apresentaram maiores massas de forragem do que aqueles diferidos com 15 e 25cm. O pasto diferido com 15cm apresentou maior porcentagem de folha e menor percentual de colmo morto, em comparação aos demais pastos. A seleção por folha morta aumentou no período de pastejo. Em geral, nos pastos diferidos mais altos, os percentuais de folha viva foram menores e os de colmo morto, maiores nas amostras de pastejo simulado. O desempenho dos ovinos foi superior no pasto diferido com 15cm, intermediário nos pastos diferidos com 25 e 35cm, e inferior no pasto diferido com 45cm. A manutenção do capim-marandu com 15cm no início do diferimento resulta em pasto com melhor morfologia, otimiza a seletividade e aumenta o desempenho dos ovinos no inverno.

Nitrogen fertilisation allows to modulate the growth of forage canopy during the deferment period. We evaluated the morphogenic characteristics, during the initial and final phases of the deferment period, of young, mature and old tillers of Brachiaria brizantha cv. Marandu. fertilised with low and high doses of nitrogen (N). The design was completely randomised, in a subdivided plot scheme, with four replications. Leaf appearance rate (LAR) and leaf elongation rate (LER) were higher in young tillers than in old ones. At the beginning of the deferment period, the canopy under high N doses had higher LAR and LER values. At the end of the deferment period, we observed no difference between the doses of N for LAR. The stem elongation rate was higher at the beginning than at the end of the deferment period, while the leaf senescence rate (LSR) was higher at higher N doses when compared to lower doses. The highest LSR values and leaf lifespan were observed at the end of the deferment period. The greatest number of young tillers occurred at the beginning of the deferment period and with the highest N dose. In this sense, higher N doses, applied during the active growth period and before the deferment period, favour he maintenance of a larger number of young tillers, which have a greater growth potential.

In deferred pastures, nitrogen fertilisation and pasture height at the beginning of the deferment period modify the structure and nutritive value of forage. This work was conducted to determine the nitrogen (N) doses and sward heights that were adequate for the deferment of Brachiaria brizantha cv. Marandu syn. Urochloa brizantha cv. Marandu (marandu palisadegrass). Two sward heights (15 and 30 cm) and four N rates (0, 40, 80,120 kg/ha) at the beginning of the deferment period were evaluated in a randomised block design and a factorial scheme with three replications. At the end of the deferment period, the numbers of live and dead tillers, the numbers of tillers with different sizes, the masses of live leaf lamina, dead leaf lamina, live stem and dead stem, the litter mass and the crude protein and neutral detergent fibre contents of the forage were evaluated. With nitrogen fertilisation, there was an increase in the masses of live leaf and live stem in the deferred canopy. With the application of 80 kg/ha of N, the litter mass was higher in the deferred canopy with a height of 30 cm, in relation to that with a height of 15 cm. The highest canopy presented greater stem mass and worse nutritional value when compared to the lowest one. In order to improve forage characteristics, marandu palisadegrass can be deferred by 15 cm and fertilised with 80 kg/ha N. When marandu palisade grass is deferred to 30 cm, nitrogen doses lower than 80 kg/ha can be applied.

Satisfactory tillering is the basic attribute to ensure stability and productivity of a grass population. We aimed to develop an understanding of tillering in Urochloa brizantha syn. Brachiaria brizantha cv. Marandu (Marandu palisadegrass) maintained at constant or variable heights during the various seasons of the year and to identify defoliation strategies that optimize tillering. In an experiment conducted in Uberlândia, Minas Gerais, Brazil, 3 defoliation strategies were studied: sward kept at 30 cm during the whole year (constant height); kept at 15 cm in fall/winter, 30 cm in spring and 45 cm in summer (increasing height); and kept at 45 cm in fall/winter, 30 cm in spring and 15 cm in the summer (decreasing height). The experiment was completely randomized, with 4 replicates. The following variables were evaluated: tiller appearance (TAR), mortality (TMR) and survival (TSR) rates; the balance (BAL) between TAR and TMR; tiller population stability (TPS); and number of tillers/m 2 (NT). In winter and late spring, TAR and BAL were low, while in early spring, the sward with decreasing height showed high TAR, BAL and TPS. The NT was higher when managed with increasing height than with other height strategies. Lowering pasture height from 45 to 30 cm after the winter increased TAR in early spring. Grazing studies seem warranted to assess how these results can be reproduced under grazing and how pasture yield and quality plus animal performance compare with those under the fixed grazing height regimen.Keywords: Defoliation, grazing management, pasture height, tillers, Urochloa brizantha. ResumenLa capacidad para formar macollas es un atributo básico para garantizar la sostenibilidad y productividad de una población de plantas en una pastura. En Uberlândia, Minas Gerais, Brazil se evaluó el macollamiento de Urochloa brizantha (syn. Brachiaria brizantha) cv. Marandú manejado a alturas constantes o variables durante las diferentes estaciones del año con el objetivo de identificar las estrategias de defoliación que optimicen el macollamiento de este cultivar. Las estrategias de defoliación consistieron en: pastura a una altura de 30 cm a través del año (altura constante); pastura a 15 cm en otoño/invierno, 30 cm en primavera y 45 cm en verano (altura creciente); y pastura a 45 cm en otoño/invierno, 30 cm en primavera y 15 cm en verano (altura decreciente). El diseño del experimento fue completamente al azar, con 4 repeticiones. Las variables evaluadas fueron: tasas de aparición de rebrotes (TAR), mortalidad de rebrotes (TMR) y supervivencia de rebrotes (TSR); equilibrio (BAL) entre TAR y TMR; estabilidad de la población de rebrotes (TPS); y número de rebrotes/m 2 (NT). En invierno y hacia finales de la primavera, TAR y BAL fueron bajos, mientras que a principios de la primavera, el tratamiento decreciente mostró altos TAR, BAL y TPS. El NT fue mayor en el ___________ Correspondence: G.P. Silva, University of São Paulo/ESALQ, Department of Animal Science, Av. Pádua Dias, 11, Agronomia, Piracicaba CEP 13418-90...

The objective of this study was to evaluate the apparent selectivity of sheep in marandu palisadegrass (Urochloa brizantha cv. Marandu) pastures with four heights at the beginning of the deferment period (15, 25, 35 and 45cm). The deferment period was 92 days and started on 03/21/2014. Evaluations occurred in the beginning (first week), middle (45th day) and end (92nd day) of the grazing period, in winter (06/21/2014 to 09/21/2014). Deferred pastures with 15 and 25cm presented lower forage mass (FM), but higher live leaf (LL) percentage in FM than deferred pastures with 35 and 45cm. The live stem percentage in the FM and the apparent selectivity index (ASI) of the LL were superior in the deferred pasture with 45cm. The dead stem (DS) percentage in the grazing simulation (GS) and the ASI of this morphological component were lower in the pasture with 15cm, compared to the deferred pasture with 45cm. The FM and the LL percentages in FM and in the GS sample decreased, while the DS percentages in FM and in GS sample increased with the grazing period. Marandu palisadegrass with 15cm at beginning of the deferment period improves the morphology of the deferred pasture. Selective grazing is difficult during the grazing period.

The deferred pasture structure determines the consumption and performance of grazing animals and, in addition, can be influenced by the duration of the deferment period and nitrogen (N) fertilisation. The objective of this work was to evaluate the structural characteristics of Brachiaria brizantha syn. Urochloa brizantha cv. Piatã (piatã palisadegrass) deferred for two periods (79 and 127 days) and with four N doses (0, 40, 80 and 120 kg ha-1) in the Zona da Mata of Minas Gerais, Brazil. The experimental design involved complete randomised blocks and a subdivided plot scheme, with three replications. The 127-day period of deferment resulted in a higher forage mass, falling index, stem percentage and density, but a lower number of tillers, percentage and volumetric density of live leaf blade. The N dose increment, in general, worsened the structural characteristics of the piatã palisadegrass deferred for 127 days. However, with the 79-day period, the N fertilisation increased the volumetric density of live leaf blades and reduced the stem percentage in the forage mass. As a preliminary recommendation, piatã palisadegrass can be deferred for 79 days and fertilised with up to 90 kg ha-1 of N in the region of Zona da Mata de Minas Gerais, Brazil.

ResumoEste estudo avaliou as características estruturais de perfilhos, com diferentes idades, do capimmarandu (Urochloa brizantha cv. Marandu) diferido e adubado. Foram avaliadas duas doses de nitrogênio (baixa, 50 kg ha -1 e alta, 200 kg ha -1 ), três categorias de idades de perfilhos (jovem, < 2 meses; maduro, 2 a 4 meses; e velho, > 4 meses;), além de dois períodos (início, 1 a 45 dias e fim, 46 a 90 dias) durante o diferimento. O delineamento experimental foi inteiramente casualizado, em esquema de parcela sub-subdividida, com quatro repetições. De modo geral, o perfilho jovem apresentou melhor composição morfológica (40,0% de lâmina foliar viva, P=0,0074; 39,2% de colmo vivo, P=0,0208; e 20,8% de lâmina foliar morta, P=0,0155), enquanto que o perfilho velho teve pior morfologia (7,3% de lâmina foliar viva; 54,8% de colmo vivo; e 38,0% de lâmina foliar morta) ao término do período de diferimento. A percentagem de perfilho velho foi maior (P=0,0019) no fim (54,0%) do que no início (43,4%) do período de diferimento. No início do diferimento o dossel adubado com alta dose de N apresentou (P=0,0447) maior percentual de perfilho jovem (36,8%) do que aquele sob baixa dose de N (28,6%). No fim do período de diferimento, tanto a alta como a baixa dose de nitrogênio resultaram (P=0,0276) em valores similares de perfilho jovem no dossel diferido (24,3%, em média). A maior dose de N, parcelada antes do período de diferimento, aumenta o percentual de perfilho jovem durante a fase inicial do diferimento. O perfilho jovem tem melhores características estruturais do que os perfilhos maduros e velhos. Palavras-chave: área foliar; composição morfológica; número de perfilho; Urochloa brizantha. AbstractThe structural characteristics of tillers with different ages of deferred and fertilized marandu palisade grass (Urochloa brizantha cv. Marandu) were evaluated. Two doses of nitrogen (low, 50 kg ha -1 and high, 200 kg ha -1 ), three age categories of tillers (young, <2 months, mature, 2 to 4 months, and old,> 4 months), and to two periods (beginning, 1 to 45 days and end, 46 to 90) during deferral were 2 CARVALHO, A.N. et al.Cienc. anim. bras., Goiânia, v.20, 1-12, e-44460, 2019 evaluated. The experimental design was completely randomized, in a subsubdivide plot scheme, with four replications. In general, young tiller had a better morphological composition (40.0% live leaf, P=0.0074; 39.2% live stem, P=0.0208; and 20.8% dead leaf blade, P=0.0155), while the old tiller had a worse morphology (7.3% live leaf, 54.8% live stem and 38.0% leaf dead) at the end of the deferral period. The percentage of old tillers was higher (P=0.0019) at the end (54.0%) than at the beginning (43.4%) of the deferment period. At the beginning of the deferment the canopy fertilized with high dose of N presented (P=0.0447) a higher percentage of young tiller (36.8%) than that under low N dose (28.6%). At the end of the deferment period, both the high and the low nitrogen doses resulted (P=0.0276) in similar values of young tiller in the deferred canopy (2...

The objective of this study was to evaluate the morphogenic and structural characteristics of the Brachiaria brizantha cv. Marandu Syn. Urochloa brizantha cv. Marandu during the different seasons of the year, in locations closer to or farther from feces deposited by cattle in pastures. The experimental design was in randomized blocks, with four replicates. The following response-variables were calculated: phyllochron (PHYL), leaf appearance rate (LAR), leaf elongation rate (LER), stem elongation rate (SER), leaf senescence rate (LSR), life span of the leaf (LSL), stem length (SL), leaf blade length (LBL), number of dead leaves per tiller (NDLT), and number of living leaves per tiller (NLLT). Farther from the feces, a larger phyllochron period was observed in all seasons. The LSL was greater in winter, especially farther from feces. Closer to feces, higher values were observed for LAR, LER and LBL compared with the sites farther from feces. The SL, SER, and NLLT were lower in the winter compared with the other seasons. In the summer, a greater NDLT value was observed than in the other seasons. The deposition of feces by cattle and the seasons of the year both affect the morphogenesis of B. brizantha cv. Marandu, generating the observed spatial and temporal variability in pasture grass. Key words: Brachiaria brizantha syn. Urochloa brizantha. Growth. Tiller. Senescence. ResumoObjetivou-se avaliar as características morfogênicas e estruturais da Brachiaria brizantha cv. Marandu Syn. Urochloa brizantha cv. Marandu durante as estações do ano em locais próximos ou distantes das fezes depositadas pelos bovinos na pastagem. O delineamento experimental foi em blocos ao acaso, com quatro repetições. Foram calculadas as seguintes variáveis-respostas: filocrono (FIL), taxa de aparecimento foliar (TApF), taxa de alongamento foliar (TAlF), taxa de alongamento de colmo (TAlC), taxa de senescência foliar (TSeF), duração de vida da folha (DVF), comprimento do colmo (CC), comprimento da lâmina foliar (CLF), número de folhas mortas por perfilho (NFM) e número de folhas vivas por perfilho (NFV). Distante das fezes foi observado maior filocrono, independente da estação do ano. A DVF foi maior no inverno, sobretudo no local distante das fezes. Próximo das fezes, ocorreram maiores valores de TApF, TAlF e CLF, em relação ao local distante. O CC, TAlC e o NFV por perfilho foram inferiores no inverno,