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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Estrutura e composi??o morfol?gica do dossel de pastagens de Brachiaria brizantha cv. Marandu manejadas sob intervalos entre desfolhas fixo e vari?vel / Characteristics of the canopy in pastures of Brachiaria brizantha cv. Marandu submitted at intervals enters takes away the leaves fixture or in agreement 0 variable the luminous interception

Jord?o, Alisson Rodrigues 23 February 2010 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-03-29T14:12:43Z No. of bitstreams: 1 2010- Alisson Rodrigues Jord?o.pdf: 2054638 bytes, checksum: 81c1a25c3f7d3cc94c71f64464696a47 (MD5) / Made available in DSpace on 2017-03-29T14:12:43Z (GMT). No. of bitstreams: 1 2010- Alisson Rodrigues Jord?o.pdf: 2054638 bytes, checksum: 81c1a25c3f7d3cc94c71f64464696a47 (MD5) Previous issue date: 2010-02-23 / Funda??o Carlos Chagas Filho de Amparo ? Pesquisa do Estado do RJ - FAPERJ / In animal production systems that utilize grazing, changes in sward structural characteristics can be determined by the management strategy used, and under rotational grazing, the use of flexible period of rest as light interception may provide greater accumulation of liquid forage and reduce the proportion of stem and dead material, increasing the efficiency of harvesting forage for animals. In this context, this study aimed to evaluate the effects of stocking regimes characterized by intermittent intervals between defoliations fixed or variable depending on the light interception of 95% on the sward structure and morphological composition of the forage in Brachiaria brizantha cv. Marandu. The experiment was conducted at the Experimental Field of Coronel Pacheco (HNSCC), EMBRAPA Dairy Cattle in the city of Coronel Pacheco - MG, from March to June 2009, lasting 95 days. The experiment was conducted following a randomized complete block design with two plots. The treatments consisted of rotational grazing strategies characterized by the entry of animals in the paddocks where they had 95% light interception by the canopy and the other with fixed interval between defoliations 30 days, both allocated to paddocks with an average area of 820 m2 each. In both treatments, the height of the residue after grazing established was 25 cm. The variables studied were: frequency of defoliation, height, forage mass, bulk density, and morphological composition of the forage. The grazing strategy defined by the IL 95%, due to its higher frequency, had shorter intervals between defoliations (FDI), reflecting a lower dry matter production of forage for grazing cycle in relation to FDI strategy with fixed 30 days but higher number of grazing cycles that the fixed interval. Overall, the average canopy height in the pre-grazing condition decreased in both management strategies during the trial period, reflecting the decline in conditions favorable for plant growth. The strategy based on 95% IL possible to maintain the height of the residue after grazing closer to the target (25 cm) to greater control over the reproductive activity in plants, as compared with that based on 30 days fixed. No difference was observed dry mass of leaf blades between grazing strategies in pre-grazing condition. The management based on IL 95% resulted in a higher dry leaf in the residue after grazing with consequent increase in the frequency of grazing. The strategy of grazing with FDI fixed set for 30 days showed a greater participation of stem and dead material in herbage mass in pre and post-grazing, in relation to strategy with 95% IL. Thus, management of pastures with IED set for 95% of IL allows a more effective control of sward structure and better morphological composition of these systems for crop and animal production, even in times of adverse weather conditions / Nos sistemas de produ??o animal que utilizam o pastejo, as varia??es nas caracter?sticas estruturais do dossel forrageiro podem ser determinadas pela estrat?gia de manejo utilizada, e sob pastejo rotativo, o uso de per?odo de descanso flex?vel, conforme a intercepta??o luminosa pode determinar maior ac?mulo liquido de forragem e redu??o da propor??o de colmos e material morto, aumentando a efici?ncia de colheita de forragem pelos animais. Neste contexto, o presente estudo objetivou avaliar os efeitos de regimes de lota??o intermitente caracterizados por intervalos entre desfolhas fixo ou vari?veis conforme a intercepta??o luminosa de 95%, sobre a estrutura do dossel forrageiro e composi??o morfol?gica da forragem em pastagens de Brachiaria brizantha cv. Marandu. O experimento foi conduzido no Campo Experimental de Coronel Pacheco (CECP), da EMBRAPA Gado de leite, no munic?pio de Coronel Pacheco ? MG, de mar?o a junho de 2009, com dura??o de 95 dias. O experimento foi realizado seguindo um delineamento de blocos completos casualizados com duas repeti??es de ?rea. Os tratamentos corresponderam a estrat?gias de pastejo rotativo caracterizadas pela entrada dos animais nos piquetes quando estes apresentavam 95% de intercepta??o luminosa pelo dossel e o outro com intervalo entre desfolhas fixo de 30 dias, ambos alocados em piquetes com ?rea m?dia de 820 m2 cada. Em ambos os tratamentos a altura do res?duo p?s-pastejo estabelecia foi de 25 cm. As vari?veis estudadas foram: freq??ncia de desfolhas, altura, massa de forragem, densidade volum?trica e composi??o morfol?gica da forragem. A estrat?gia de pastejo definida pela IL de 95%, devido a sua maior freq??ncia, apresentou menores intervalos entre desfolhas (IED), refletindo em uma menor produ??o de massa seca de forragem por ciclo de pastejo em rela??o ? estrat?gia com IED fixo de 30 dias, por?m com maior n?mero de ciclos de pastejo que o intervalo fixo. No geral, as m?dias de altura do dossel na condi??o de pr?-pastejo decresceram em ambas as estrat?gias de manejo durante o per?odo experimental, reflexo da diminui??o das condi??es favor?veis ao crescimento das plantas. A estrat?gia baseada na IL de 95% permitiu manter a altura do res?duo p?s-pastejo mais pr?xima da meta estabelecida (25 cm) com maior controle sobre a atividade reprodutiva das plantas, em compara??o com aquela baseada em 30 dias fixos. N?o foi verificada diferen?a na massa seca de l?minas foliares entre as estrat?gias de pastejo na condi??o de pr?-pastejo. O manejo baseado na IL de 95% resultou em uma maior massa seca de l?minas foliares no res?duo p?s-pastejo com conseq?ente aumento da freq??ncia de pastejo. A estrat?gia de pastejo com IED definido por 30 dias fixos apresentou uma maior participa??o de colmos e material morto na massa de forragem nas condi??es de pr? e p?s-pastejo, em rela??o ? estrat?gia com 95% de IL. Dessa forma, o manejo dos pastos com IED definidos por 95% de IL permite um controle mais efetivo da estrutura do dossel forrageiro e uma melhor composi??o morfol?gica dos mesmos para os sistemas de produ??o vegetal e animal, mesmo em ?pocas de condi??es clim?ticas desfavor?veis.

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