Sward structure and nutritive value of tanzania guineagrass subjected to rotational stocking managements

Abstract

The objective of this work was to evaluate the sward structure and nutritive value of Panicum maximum Jacq. cv. Tanzânia subjected to rotational stocking managements characterised by a common pre-grazing condition of 95% canopy light interception (LI) and two post-grazing residues, 25 and 50 cm. Treatments (95/25, 95/50 - LI/residue) were assigned to experimental units (groups of six 2500 m² paddocks per treatment) according to a complete randomised block design, with two replications. The variables measured corresponded to: canopy light interception, pre and post-grazing sward height, herbage mass and pre and post-grazing morphological composition, herbage bulk density, herbage accumulation and nutritive value (including to IVOMD) of the morphological components. Pre-grazing herbage mass did not differ between residues, although the herbage accumulation rate was higher for the 50 than the 25 cm (164.9 and 90.6 kg/ha.day DM, respectively). Post-grazing herbage mass values were higher for the 50 cm residue and were characterised by a higher proportion of leaf blade in relation to the 25 cm treatment, which presented a higher proportion of dead material. On average, the contents of crude protein (CP), neutral detergent fibre (NDF) and lignin in acid detergent (LAD) as well as the values of the "in vitro" organic matter digestibility (IVOMD) were similar for both treatments. Crude protein and IVOMD decreased and NDF and LAD increased from top to the bottom of the sward, indicating grazing intensity as an important variable for promoting adjustments in the grazing efficiency and nutritive value of the consumed herbage by the grazing animals.

Herbage accumulation and grazing losses on Mulato grass subjected to strategies of rotational stocking management

“…On the other hand, swards managed at 99 % LI were grazed a smaller number of times during the experiment (Table 1) Grazing efficiency (%) Seasons B grazed at 95 % LI and/or with the post-grazing height of 15 cm. Such a result is consistent with the more favorable structural conditions of the sward canopy for grazing (Hirata et al, 2010) on swards managed at 95 % LI, and corroborates the results of Carnevalli et al (2006) and Difante et al (2009), from analogous experiments, for mombaça and tanzania grasses, respectively. However, only a portion of the herbage removed was actually consumed by the grazing animals.…”

“…Inherent to the optimal implementation of this stocking method is the basic assumption that the correct time is known for interrupting the regrowth process to maximize leaf dry matter accumulation and achieve high levels of grazing efficiency. Recent studies conducted with tropical forage grasses (Difante et al, 2009;Cunha et al, 2010) have indicated that 95 % light interception (LI) corresponds to the appropriate time for interrupting the regrowth process of species because it maximized leaf dry matter accumulation and ensures high grazing efficiency (Carnevalli et al, 2006). To ensure high levels of intake and performance, grazing should be interrupted when sward height reaches 40 to 60 % of the pre-grazing height (Fonseca et al, 2012).…”

Características do pasto e eficiência agronômica de nitrogênio em capim-tanzânia sob pastejo contínuo, adubado com doses de nitrogênio

“…Essas características agronômicas são encontradas com o capim-tanzânia Ciência Rural, v.43, n.4, abr, 2013. (CANTO, 2003;EUCLIDES et al, 2007b;DIFANTE et al, 2009).…”

“…Estudos mostram que, em pastagens de capimtanzânia sob pastejo contínuo, durante a estação do inverno, a altura do pasto pode alterar características do pasto (CANTO et al, 2001) e, em consequência, o desempenho de novilhos de corte (CANTO et al, 2002). Os trabalhos com essa gramínea com o método de pastejo rotativo indicam que a altura do pasto afetou características do pasto, o valor nutritivo (DIFANTE et al, 2009), a conversão alimentar, o desempenho por animal e o ganho/ha (DIFANTE et al, 2010).…”

Dinâmica do crescimento e componentes do acúmulo de forragem de capim-elefante cv. Napier submetido a estratégias de pastejo rotativo

“…A consequência desse manejo é a falta de consistência e repetibilidade dos resultados, assim como oscilações na produção, composição morfológica e valor nutritivo da forragem produzida entre ciclos de avaliação ao longo de uma mesma estação de crescimento e entre localidades e anos distintos. Nesse sentido, à semelhança de trabalhos conduzidos com espécies de Panicum DIFANTE et al, 2009) e capim-marandu (GIACOMINI et al, 2009), a interceptação luminosa foi utilizada como critério de interrupção da rebrotação do capim-elefante. Voltolini (2006) e Carareto (2007) compararam a utilização da meta de 95% de interceptação luminosa pelo dossel (IL) com o manejo baseado em 27 dias fixos em pastos de capim-elefante cv.…”