The objective of this study was to evaluate the effects of stalk/leaf ratio and the stage of maturity on the digestibility of the corn plant. Hybrids AG1051, AG4051, AG5011, DOW2B710, DOW2C577, DOW2A525, NB7315 and P30F90 were used, harvested at the one-half milk line (½ ML), three-quarters milk line (¾ ML) and black layer (BL) stages. A randomized block design was used in an 8 (hybrids) × 3 (stages of maturity) factorial design, with three replications. The means generated were used for grouping into high and low stalk/leaf ratio and a new analysis of variance was generated in a 2 × 3 (two groups and three stages of maturity) factorial design. The whole plant and its stalk, leaf, husk, cob and grain components were incubated in situ in the rumen of three cows for determination of degradability of dry matter and degradable neutral detergent fiber. Stalk/leaf ratio did not influence neutral detergent fiber content or the degradability of dry matter and neutral detergent fiber of any of the components, except for the cob, in which the high ratio group had greater degradable neutral detergent fiber contents. There was a reduction in the degradability of all the parts, except for the stalk and cob, and an increase in the neutral detergent fiber contents of the vegetative parts, except for the stalk. Unlike the vegetative components, the neutral detergent fiber contents of the whole plant decreased throughout the stages evaluated. For degradable neutral detergent fiber, there was a reduction in the whole plant and in its components. The advance of maturity reduces the quality of the vegetative components; however, this loss in the entire plant is moderated by grain filling. Forage quality depends more on the quality of the components than on their proportions in the dry matter.

A pesquisa foi conduzida na Fazenda Porto, município de Alfenas-MG, e objetivou-se determinar o efeito da dosagem de dejetos líquidos de suínos, na produtividade da cana-de-açúcar. Utilizaram-se dejetos líquidos de suínos nas dosagens de 0, 40, 80, 120, 160 e 200 m³/ha, aplicados em uma vez, e adubação química convencional, em uma lavoura de cana-de-açúcar de 2º corte, variedade SP81-3250, em latossolo vermelho escuro distrófico (LVEd). O delineamento utilizado foi o de blocos casualizados com quatro repetições. Para comparação de médias, utilizou-se o programa SISVAR e o teste de Scott-Knott. A colheita foi feita um ano após a implantação do experimento. Foram determinadas a produtividade agrícola e a qualidade tecnológica da cana-de-açúcar. A dosagem de 40 m³/ha equivaleu à adubação química, sendo que as demais apresentaram produtividades agrícolas superiores de 76,5% a 96,3% maior que a testemunha, que foi de 58,10t/ha. Quanto à qualidade tecnológica dos colmos, não foi verificada diferença estatística. Os dejetos líquidos de suínos proporcionaram aumentos significativos na produtividade de colmos da cana-de-açúcar, não comprometendo a qualidade tecnológica.

The present research was carried out at Fazenda Porto, Alfenas-MG, with the purpose of determining the effect of doses of swine wastewaters on sugarcane productivity. Two types of fertilization were tested on a second-cut sugarcane plantation, variety SP 81-3250, on dark red dystrophic latosol (LVEd): (1) swine wastewaters were used in the doses of 0, 40, 80, 120, 160 and 200 m³/ha, and applied all at once and (2) conventional chemical fertilization. The experimental design used was the randomized blocks with four replications. To compare the means, the SISVAR program and the Scott-Knott test were used. The harvest was made one year after the experiment implantation. The agricultural productivity and technological quality of sugarcane were determined. The dose of 40 m³/ha was equivalent to the chemical fertilizing, while the others showed 76.5% - 96.3% higher productivity when compared to the reference plantation (58.10t/ha). No statistical difference was found with regard to the technological quality of the stalks. The swine wastewaters provided significant increases in the sugarcane stalk productivity without jeopardizing the technological quality.

Com o objetivo de avaliar a influência de diferentes épocas de semeadura na produtividade e qualidade de cultivares de milho e sorgo para silagem e também verificar a possibilidade de substituição do milho pelo sorgo para produção de silagem, foram instalados experimentos em três épocas de semeadura, em área do Departamento de Agricultura da Universidade Federal de Lavras, no ano agrícola 2002/2003. Foram avaliados três grupos de cultivares - três cultivares de sorgo duplo propósito, três de sorgo forrageiro e três de milho, em três épocas de semeadura - 19/11/2002, 19/12/2002 e 18/1/2003). O delineamento utilizado foi o de blocos casualizados, em esquema fatorial 3 (grupos de cultivares) x 3 (épocas de semeadura), com quatro repetições. Avaliaram-se produtividade de matéria seca (MS), participação de panícula ou espiga na MS, e as porcentagens de proteína bruta, fibra em detergente neutro (FDN), fibra em detergente ácido (FDA) e lignina. Observou-se efeito significativo para cultivares e épocas de semeadura para todas as características avaliadas. Constatou-se a presença de interação cultivares*épocas para a produtividade de matéria seca (MS), participação de panícula ou espiga na MS e porcentagem de proteína bruta. Independentemente de época semeadura, com o milho se tem silagem com menor teor de fibra do que com qualquer tipo de sorgo e produtividade de matéria seca semelhante à do sorgo forrageiro e maior do que o sorgo duplo propósito. A maior produção de matéria seca de milho e sorgo, para forragem, é obtida na semeadura em novembro. Silagem de milho e sorgo de maior valor nutritivo é obtida na semeadura de janeiro. Do ponto de vista de produção e de qualidade nutricional da forragem, não é viável a substituição da silagem de milho pela de sorgo.

With the objective to evaluate the influence of different times of sowing in the productivity and silage quality of corn and sorghum cultivars and also of verifying the possibility of substitution of corn to sorghum to silage production, experiments were installed considering three times of sowing in area of the Department of Agriculture of the Federal University, during the agricultural year of 2002/2003. Three groups had been evaluated to cultivars (three of double purpose sorghum, three of forage sorghum and three of corn) at three times of sowing (19/11/2002, 19/12/2002, and 18/1/2003). The experimental design was of blocks randomized in factorial scheme 3 groups to cultivars (to cultivars) x 3 times of sowing (times), with four repetitions. Productivity of dry matter was evaluated (MS), participation of panicle or spike in the MS, and the rude protein percentages, fiber in neutral detergent, fiber in acid detergent and lignin. Significant effect was observed to cultivars, times of sowing to all characteristics evaluated. The presence of interaction cultivars*times was verified for the productivity of dry matter, participation of panicle or spike in the MS and the rude protein percentages. Independently of times of sowing, with the corn present silage with smaller fiber tenor than with any sorghum types, and productivity of dry matter similar to the one of forage sorghum and superior to the one of sorghum of double intention. The largest production of dry matter of corn and sorghum was obtained when the sowing is made in November. Corn and sorghum silage of larger nutritional value was obtained when the sowing was made in January. Under the production point of view and of quality nutritional of the forage, it is not viable the substitution of the corn for sorghum.