Dinámica del rebrote en pasto insurgente (brachiaria brizantha hochst. stapf.) pastoreado a diferente asignación en la estación de lluvias (original) (raw)
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Regrowth dynamics of Insurgente grass (Brachiaria brizantha Hochst. Stapf.) grazed at different allowances in the rainy season RESUMEN El objetivo del presente estudio, fue describir el rebrote de insurgente cosechado por pastoreo a diferente asignación de hoja verde, en términos de la cantidad total y por componente de forraje e hijuelos, en un esquema de pastoreo rotacional con período fijo de descanso, en la época de lluvias, pastoreado a tres asignaciones: 3, 5 y 7 kg MS de hoja por 100 kg peso vivo -1 día -1 . El diseño fue bloques al azar con tres repeticiones y la unidad experimental consistió en un potrero de 0.5 ha con dos vaquillas. El pastoreo fue rotacional con tres días de ocupación y 30 para rebrote. Se completaron cuatro ciclos de pastoreo. La menor asignación registró el mayor (P<0.05) grado de defoliación (68 %) y un patrón diferente de rebrote del insurgente, en comparación a las otras dos asignaciones que no mostraron diferencia (P>0.05) entre ellas en el grado de defoliación (49 %). Las tasas diarias de acumulación de peso fueron menores (P<0.05) en la asignación del 3 % en los primeros 15 días pero mayores (P<0.05) en los últimos 15 días del período de rebrote, en comparación a las otras dos asignaciones. Este diferente patrón de rebrote ocasionó que al final del mismo (30 días) no se registraran diferencias (P>0.05) entre asignaciones en biomasa aérea total y por componentes. Se concluyó que la dinámica del rebrote en el pasto insurgente varía con la intensidad de cosecha, y que esto permite que el grado de recuperación sea similar al final de un período de rebrote de 30 días en la época de lluvias.
Revista Brasileira de Zootecnia, 2013
The objective of this study was to evaluate grazing management strategies of Brachiaria decumbens cv. Basilisk managed with different heights under continuous grazing with cattle. Two grazing management strategies were evaluated: maintenance of pasture with an average height of 25 cm throughout the experimental period and maintenance of pasture on the average of 15 cm in height during winter, up to 25 cm from the beginning of spring. The split-plot scheme and the randomized block design with four replications were adopted. The grazing management strategies corresponded to the primary factor, while the seasons (winter, spring and summer) corresponded to secondary factor. The reduction of the average sward height to 15 cm in the winter resulted, when compared with pasture maintained at 25 cm, in overall higher growth rates (95 kg/ha.day DM) and leaf blade (66.1 kg/ha.day DM), as well as higher rates of total accumulation (81.5 kg/ha.day DM) and leaf blade (52.6 kg/ha.day DM). The accumulated forage production (from winter to summer) was higher in the pasture lowered to 15 cm in winter (25.6 t/ha DM) compared with that managed with an average height of 25 cm (22.2 t/ha DM). Regarding the seasons of the year, in the winter, there were lower rates of overall growth (6.4 kg/ha.day DM), leaf blade (5.6 kg/ha.day DM) and pseudostem (0.8 kg/ha.day DM), and also lower total (-6.6 kg/ha.day DM) and leaf blade (-7.5 kg/ha.day DM) accumulation rates. In the spring there was a higher rate of leaf senescence (22.4 kg/ha.day DM). The accumulation of forage is incremented when the pasture of B. decumbens is lowered to 15 cm during the winter, and in the spring and summer, its average height is increased to 25 cm.
In ruminant-forage systems herbage allowance (HAL) has a major impact on grazing intensity and sward structure, affecting animals, plants, and ultimately, pasture yield. Data on HAL responses of tropical cultivated pastures are scarce and this information may be useful in optimizing pasture utilization. The objective of this study was to describe and contrast sward structure and herbage accumulation responses of 'Marandu' palisadegrass [Brachiaria brizantha (A.Rich.) Stapf] pastures to HAL during two grazing seasons (warm-rainy season of 2003 and 2004). Treatments were four daily HAL levels, 5, 10, 15 and 20 kg herbage mass per 100 kg live weight (%) in a rotational stocking system with 35 days of grazing cycle (28-day rest; 7-d grazing). Post-graze swards were shorter (~17 cm) under 5% HAL. For the other HAL levels, postgraze sward height increased throughout the experiment (21 to 50 cm). Changes in sward light interception (LI) were highly associated with height, but differed across HALs in 2004. Early in the 2003 season, HAL increases resulted in linear increase of the daily herbage accumulation rate (HAR; 47, 66, 78, and 98 kg DM ha-1 d-1 for 5, 10, 15 and 20%-HAL, respectively). For the subsequent grazing cycles of 2003 and all through 2004, HAR decreased with increasing HAL. This was associated with the excessive increase in sward height and mean forage mass, caused by lower grazing intensity. The use of lax (high) HAL to maximize animal performance, especially 10, 15 and 20%-HAL, resulted in decreased pasture performance (lower herbage accumulation, HAC) in palisadegrass pastures. ESTRUTURA DO DOSSEL E PRODUÇÃO DE FORRAGEM EM PASTAGENS DE CAPIM MARANDU [Brachiaria brizantha (A.Rich.) Stapf] SOB LOTAÇÃO ROTACIONADA EM RESPOSTA À OFERTA DE FORRAGEM RESUMO: A oferta de forragem (OF) aos animais em pastejo causa forte impacto na intensidade de desfolhação e conseqüentemente na estrutura do dossel, influindo indiretamente no acúmulo de forragem. O objetivo deste estudo foi avaliar estrutura do dossel e acúmulo de forragem em pastagens de capim-Marandu em resposta à OF. Os tratamentos foram quatro OFs, 5, 10, 15 e 20 kg massa de forragem por 100 kg peso vivo por dia (%), em ciclos de pastejo de 35 dias (28 d de descanso e 7 d de ocupação). A altura do dossel no pós-pastejo foi mais baixa para a OF 5%, que se manteve em torno de 17 cm, enquanto que para as demais houve aumento progressivo dos valores ao longo do experimento (21 a 50 cm). A variação na interceptação de luz (IL) em função da altura do dossel foi significativa, e em 2004 diferiu entre OFs. Inicialmente o aumento da OF resultou em aumento linear da taxa diária de acúmulo de forragem (TAF), com 47, 66, 78 e 98 kg forragem ha-1 (ciclo I – 2003), nas pastagens sob OF 5, 10, 15 e 20%, respectivamente. Entretanto, nas rebrotações posteriores houve diminuição acentuada da TAF para OFs mais elevadas, condição que persistiu no segundo ano do experimento (2004), e foi associada ao excessivo aumento da altura do dossel e da massa de forragem, como conseqüência da diminuição da intensidade de pastejo. A utilização de OFs generosas com intuito de elevar o desempenho animal, trouxe conseqüências negativas sobre o acúmulo de forragem em pastagens de capim Marandu. Palavras-chave: acúmulo de forragem, altura do dossel, interceptação de luz, massa de forragem Braga et al.
Scientia Agricola, 2006
In ruminant-forage systems herbage allowance (HAL) has a major impact on grazing intensity and sward structure, affecting animals, plants, and ultimately, pasture yield. Data on HAL responses of tropical cultivated pastures are scarce and this information may be useful in optimizing pasture utilization. The objective of this study was to describe and contrast sward structure and herbage accumulation responses of 'Marandu' palisadegrass [Brachiaria brizantha (A.Rich.) Stapf] pastures to HAL during two grazing seasons (warm-rainy season of 2003 and 2004). Treatments were four daily HAL levels, 5, 10, 15 and 20 kg herbage mass per 100 kg live weight (%) in a rotational stocking system with 35 days of grazing cycle (28-day rest; 7-d grazing). Post-graze swards were shorter (~17 cm) under 5% HAL. For the other HAL levels, postgraze sward height increased throughout the experiment (21 to 50 cm). Changes in sward light interception (LI) were highly associated with height, but differed across HALs in 2004. Early in the 2003 season, HAL increases resulted in linear increase of the daily herbage accumulation rate (HAR; 47, 66, 78, and 98 kg DM ha -1 d -1 for 5, 10, 15 and 20%-HAL, respectively). For the subsequent grazing cycles of 2003 and all through 2004, HAR decreased with increasing HAL. This was associated with the excessive increase in sward height and mean forage mass, caused by lower grazing intensity. The use of lax (high) HAL to maximize animal performance, especially 10, 15 and 20%-HAL, resulted in decreased pasture performance (lower herbage accumulation, HAC) in palisadegrass pastures.
Semina: Ciências Agrárias, 2016
This study aimed to evaluate the effect of three herbage allowances (5, 10, and 15 kg dry matter [DM] 100-1 of body weight [BW]) for Brachiaria brizantha cv. Marandu pastures in a continuous grazing system on the morphological and nutritional characteristics of forage, animal performance, and economic viability in Nellore heifers. The total experimental area was 60 ha, divided into 12 paddocks of 5 ha each, with 4 paddocks per treatment. The experimental animals were Nellore heifers (260 in total), with average BW of 301.16 ± 9.12 kg, receiving 0.4 % BW in multiple supplements. We evaluated the production, structural characteristics, and nutritional value of the forage, productive performance, carcass characteristics, and economic viability of each allowance. There were significant effects for the production, st uctural characteristics, and nutritional value of the forage treatment. The proportions of leaves were 42.40, 38.20, and 30.88 % and the leaf:stem ratios were 1.22, 1.03, an...
Semina-ciencias Agrarias, 2019
The objective of this study was to evaluate the effect of post-grazing residual leaf blades (RLB) of different lengths on the morphogenic and structural characteristics of Urochloa brizantha 'Piatã' grazed upon by beef cattle. A completely randomized design was used, with three RLB lengths (2, 4, and 6 cm) and two paddocks as replicates over two grazing seasons (wet and wet-dry transition). To monitor the weekly forage growth, two representative clumps and 48 tillers per treatment were marked after grazing. The procedure continued until the plants reached the target pre-grazing height of 35-40 cm. Morphogenic characteristics were not affected by the treatments or seasons, with minor changes observed in mean sheath length (MSL) within season and tiller population density (TPD). The MSL reached its peak value of 210.37 mm during the wet season relative to 175.89 mm during the wetdry transition. The TPD reached its lowest value (680 tillers m-2) at the highest defoliation intensity (2 cm) relative to that at the lowest defoliation intensity (720 tillers m-2). The different RLB lengths modified canopy height variably; canopy height was the highest with the 6 cm leaves (24.31 cm), but did not vary between the 2 cm and 4 cm leaves. The post-grazing leaf area index and interception of photosynthetically active radiation were modified by season. The highest defoliation intensity (2 cm) increased the rest period by seven days when compared with the lowest defoliation intensity (6 cm).
Signal grass structure at different sites of the same pasture under three grazing intensities
Acta Scientiarum. Animal Sciences, 2013
The experiment was conducted to evaluate Brachiaria decumbens cv. Basilisk at different sites of the same pasture featuring varying grazing intensities (under grazed, properly grazed and overgrazed). The pasture was managed under continuous stocking using 200-kg cattle and grass height kept at about 25 cm. The randomized block design was used, with three replications. Sward height (38.0 cm) and extended plant height (85.2 cm) were greater at the under grazed site. The falling index was lower at the properly grazed site (1.28). At the under grazed site, the masses of green leaf blade (3442 kg ha-1 DM), green stem (8370 kg ha-1 DM), green forage (11812 kg ha-1 DM) and total forage (14137 kg ha-1 DM) were higher when compared to the overgrazed and properly grazed sites. Dead material mass was higher at the properly grazed (3422 kg ha-1 DM) and under grazed (2324 kg ha-1 DM) sites. At the under grazed sites, there was a higher occurrence of tillers taller than 40 cm. Tillers with sizes between 10 and 30 cm predominated in properly grazed sites. In overgrazed site there was a higher share of tillers with sizes smaller than 20 cm. There is spatial variability of vegetation in the same pasture of Brachiaria decumbens cv. Basilisk due to uneven grazing by cattle.