Hélio Henrique Vilela

This study was conducted to evaluate the tiller population density and its structural characteristics in Brachiaria brizantha cv. Piata subjected to deferment periods (65, 85 and 105 days) and initial sward heights for deferment (20, 30 and 40 cm). A completely randomized block design was used in a split-plot scheme with three replications. The population density of vegetative basal and total tillers was influenced by the interaction between periods and initial heights of deferment, with lower values in the period of 85 days associated with the initial height of 40 cm and the period of 105 days associated with initial heights of 30 and 40 cm. The length of the stem and leaf blade of vegetative basal tillers increased with the raise in the deferment periods. Initial deferring heights had little effect on the structural characteristics of the tillers. The concomitant use of tall plants and long deferring periods reduces tillering of piata palisade grass. To optimize the tillering and structure of the deferred pasture in the region of Viçosa, piata palisade grass should be deferred with an initial height from 20 to 40 cm in early May and remain deferred for 65 days.

The objective of this study was to determine the deferment period and the most adequate initial sward height of Brachiaria brizantha cv. Piatã for deferment in the region of Viçosa, Minas Gerais. For so, the following characteristics were evaluated: masses and bulk density of forage and its morphological components, light interception by the sward, leaf area index, leaf angle, sward and extended tiller height and falling index of the deferred piatã grass. The three deferment periods assessed (65, 85 and 105 days) were randomized to the plots and the three sward heights (20, 30 and 40 cm), randomized in the subplots. The experimental design was of completely randomized blocks, with three replicates, in a subdivided plots arrangement. Masses of forage, green stem and dead tissue were higher in the piatã grass managed with deferment period of 105 days. The mass of green leaf blade was higher in the piatã grass deferred with 20 cm height associated to the deferment period of 85 days, which had, as consequence, greater bulk density of green leaf blade. The interception of light by the sward was greater in the piatã grass kept longer in deferment associated with the higher leaf area index, regardless of its initial height. The heights of the sward and extended tillers were greater in the piatã grass under periods of 85 and 105 days of deferment; however, the falling index was not affected by the factors studied. In the region of Viçosa, Minas Gerais, B. brizantha cv. Piatã fertilized with 75 kg/ha nitrogen and deferred with initial height of 20 cm and for a period of 85 days, from mid April, has adequate productivity and structure for animal production

This experiment was conducted to estimate the effects of nitrogen fertilization associated with the initial height of the Piata palisade grass on the number and structural characteristics of individual tillers after the deferment period. An area with Brachiaria brizantha cv. Piata measuring approximately 288 m² was used. Combinations of levels of nitrogen fertilization (0, 75 and 150 kg/ha of nitrogen) and initial heights of the sward (low - 20 cm, medium - 30 cm and high - 40 cm) were evaluated. The experimental design was of completely randomized blocks in subdivided plots with three replications. The number of vegetative tillers, the stem length of the vegetative, reproductive and dead tillers, and the number of dead leaves of the reproductive and the dead tillers linearly increased with the elevation in the nitrogen level. The deferred Piata palisade grass with low initial height showed lower number of dead basal tillers, shorter length of stems and leaf blades in reproductive tillers and lower number of live and dead leaves in vegetative tillers in relation to the one managed with height considered medium and high. Nitrogen fertilization, in association with low initial height, provides the optimization of forage of Piata palisade grass in deferment conditions

The objective of this study was to evaluate the mass of the forage and of the morphological components, and the sward structure in Piata palisadegrass (Brachiaria brizantha cv. Piata) deferred in function of different initial heights and nitrogen levels. Two levels of nitrogen (75 and 150 kg/ha) and one control without fertilization associated to three initial deferring heights (20, 30, and 40 cm) were evaluated. The design was of completely randomized blocks with three replications in a subdivided plot scheme. A raise in the initial deferment height and in the fertilization elevated the sward and extended tiller heights, the leaf area index, and the light interception by the sward. The piata palisadegrass deferred with an initial height of 40 cm presented a higher forage mass with lower percentage of leaf blades, and higher stem and dead tissue quantity. Additionally, this management strategy resulted in lower bulk density of leaf blade and in higher bulk densities of stems and dead tissue. The utilization of 150 kg/ha of nitrogen raised the production and the bulk density of deferred piata palisadegrass forage and increased production and bulk density of leaves and stems. In the region of Viçosa, Minas Gerais, the piata palisadegrass deferred with an initial height of 30 cm and fertilized with 75 kg/ha of nitrogen in the beginning of the fall presents adequate mass and structure to animal production in the winter

The objective of this research was to evaluate the effects of tiller age on morphogenic and structural characteristics of guinea grass cv. Mombaca subjected to intermittent stocking and three stubble heights: 30 cm, 50 cm and 50-30 cm. Stubble heights were assigned to experimental units in a completely randomized block design with three replicates. Grazing was performed when canopy intercepted 95% of light incidence. Leaf appearance rate, leaf elongation rate and number of live leaves per tiller were higher in the summer when compared with the winter. Contrarily, stem elongation rate, phyllochron and leaf lifespan were lower in the summer when compared with the winter. During the summer, young tillers had higher leaf appearance and elongation rates when compared with the older ones. Young and mature tillers had the highest values of live leaves per tiller in the summer. There was no difference between summer and winter for the final length of leaf blade between tillers of the same age, except in mature tillers, which had higher final leaf length during the summer. Senescence rate of leaves was higher in young tillers, followed by mature and old tillers. Age of tiller affects morphogenic and structural characteristics of pasture, showing that young tillers have better growth compared with mature and old tiller

Esta pesquisa foi conduzida no Laboratório de estudos em Metabolismo Animal da Universidade José do Rosário Vellano, em Alfenas/MG com objetivo de avaliar o efeito de maturidade do milho para ensilagem sobre o consumo de MS. As cultivares utilizadas foram: Geneze 2004, Agroceres1051, Pioneer 30S40 e Pioneer 30F90, ensiladas nos seguintes estádios de maturidade dos grãos: sem linha de leite, redução da linha de leite em 1/3 do grão, linha de leite na1/2 do grão (1/2 LL), 2/3 do grão e camada negra (CN) formada. O delineamento experimental foi em blocos casualizados, com quatro tratamentos e três repetições. O experimento foi compreendido por cinco períodos experimentais de dez dias cada, sendo o consumo avaliado durante os últimos sete dias de cada período. Foram utilizados 12 caprinos, sem raça definida, com idade média de quatro anos. A dieta dos animais foi composta de silagem de milho, fornecida as 8 e às 16 horas, sal mineral e águaad libitum. A silagem foi fornecida em quantidade suficiente para que sobrasse 10%, sendo as sobras pesadas diariamente. Não foi verificado efeito significativo(p

Objetivou-se neste trabalho avaliar as características bromatológicas de silagens de milho produzidas com milho em diversos estádios de maturação. Utilizou-se delineamento experimental de blocos casualizados, com quatro repetições, em esquema de parcelas subdivididas no tempo. Os cultivares Geneze 2004, Agroceres 1051, Pioneer 30S40 e Pioneer 30F90 foram ensilados nos seguintes estádios de maturação: grãos sem linha de leite (SLL); redução da linha de leite em 1/3 do grão (1/3 LL); 1/2 do grão (1/2 LL); 2/3 do grão (2/3 LL); e camada negra (CN) formada. A porcentagem de MS das silagens variou de 26,5 a 45,0%. As maiores perdas de efluente ocorreram nas silagens dos cultivares AG1051 e P30S40 no estádio sem linha de leite, que não apresentaram perdas a partir do estádio 1/2 LL. Com o avançar do estádio de maturação, observou-se aumento nos valores de pH. Os estádios de maturação influenciaram a porcentagem de PB das silagens, que variou de 10,7 a 8,1%. Os maiores valores de fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA) foram observados nos estádios 2/3 LL e CN. A porcentagem de lignina foi influenciada pelos cultivares e foi maior nas silagens do cultivar P30S40. A digestibilidade in vitro da matéria seca (DIVMS) foi influenciada pelos cultivares e pelos estádios de maturidade, variando de 51,1 a 69,8%, e foi maior no cultivar P30F90. A ensilagem do milho no estádio 1/2 LL promoveu melhor DIVMS, que reduziu após este estádio. Os cultivares GNZ 2004, AG1051 e P30F90 são mais indicados para ensilagem e o melhor estádio de maturidade para ensilagem desses cultivares é quando os grãos apresentam redução da linha de leite na metade do grão (1/2 LL).

Características agronômicas e bromatológicas de seis cultivares de girassol (Helianthus annuus L.), colhidas aos 95 e 110 dias após a semeadura, foram avaliadas para produção de silagem. Utilizaram-se os híbridos Cargill C 11, Braskallb DK 180, Braskallb DK 4040, Morgon M 92007, Morgon M 742 e a variedade V 2000 da EMBRAPA. O delineamento foi o de blocos casualizados, com quatro repetições, em esquema fatorial 2 x 6, sendo considerados como fatores a idade de corte e as cultivares. As plantas foram picadas mecanicamente em partículas de 2,0 a 3,0 cm de tamanho e ensiladas por 30 dias em silos de "PVC" com dez centímetros de diâmetro e quarenta centímetros de comprimento. Avaliaram-se as produções e os teores de matéria seca (MS), concentrações de proteína bruta (PB), extrato etéreo (EE), fibra em detergente neutro (FDN) e os valores de digestibilidade "in vitro" da matéria seca (DIVMS) e de pH das silagens. A maior produção de MS foi de 11,27 t/ha, enquanto a menor foi de 4,88 t/ha, respectivamente, das cultivares M 92007 e V 2000. Em relação a todas as características avaliadas das silagens, observou-se diferença significativa entre as duas idades de corte utilizadas. As cultivares apresentaram comportamento distinto para cada idade de corte analisada. Os resultados permitiram concluir que ocorrem diferenças bromatológicas nas silagens em função das cultivares e da idade de corte utilizada.