ABSTRACT: Urea is a common non-protein supplement used in ruminant feed; however, excessive consumption may lead to poisoning by NH3. Although the slow release of urea into the rumen has shown to be an essential aspect for ruminant feed, to date only a few studies have addressed this matter. In this study we examined the influence of five different NH3-N slow release systems based on clay-urea nanocomposites on the fiber digestibility of low-quality forage (sugarcane straw) in vitro. Physical properties of nanocomposites were evaluated and their effects on digestibility were tested in vitro using pristine urea as a positive control (level of 1 % of DM of sugarcane straw sample) and sugarcane (with no additives) as a negative control. Ammonia release and digestibility were evaluated at 12, 24, 36, 48, 72 and 96-h. Generally, all nanocomposites increased (p < 0.05) digestibility of fiber over control under all the conditions stipulated, but the samples with hydrogel content were more expressive. We concluded that an ideal release rate and optimum environment for microbial synthesis are necessary to maximize the digestion of sugarcane.

RESUMO. A determinação do tempo de incubação in situ, em relação ao tamanho de partículas e tipos de tecidos, é o aspecto principal sobre as estimativas das frações indigestíveis da matéria seca (MSi) e da fibra em detergente neutro (FDNi) em alimentos para ruminantes. Estudou-se amostra de alfafa, moídas em três tamanhos de partículas. As amostras foram processadas em moinho, com facas e porosidades das peneiras ajustadas a 1,0; 2,0 e 3,0 mm, as amostras foram acondicionadas em sacos F57 (Ankon(r)), tecido não tecido (100 g m-2) e tecido de poliéster, confeccionados na dimensão 4 x 5 cm. Os materiais foram divididos em 13 tempos de incubação e oito repetições, incubadas no rúmen de duas vacas multíparas adaptadas à dieta 70:30, volumoso:concentrado, respectivamente, por tempo total de 288h. Os teores de MSi e FDNi foram avaliados sequencialmente para interpretação das porcentagens de material não digerido, e os dados foram submetidos à análise de variância (ANOVA, p < 0,05), e as médias comparadas posteriormente pelo teste de tukey (p < 0,05). Houve efeito do tamanho de partículas e material utilizado para incubação sobre as estimativas de MSi e FDNi, nos tempos iniciais de incubação (p < 0,05).

ABSTRACT. Indigestible fractions of dry matter (iDM) and neutral detergent fiber (iNDF) in the feed of ruminants are mainly estimated by in situ incubation time with regard to particle size and textile types. Samples of alfafa, ground into three particle sizes, were analyzed. Samples, processed in a Willey mill with 1.0; 2.0 and 3.0 mm sieve pores, were conditioned in F57 (Ankon(r)), nonwoven (100 g m-2) and polyester textile bags measuring 4 x 5 cm. Material was divided into 13 incubation periods and 8 replications, and incubated in the rumen of two multiparous cows adapted to a 70:30 diet, roughage:concentrate, respectively, for 288h. iDM and iNDF rates were evaluated sequentially for non-digested percentage and data underwent analysis of variance (ANOVA p < 0.05); means were compared by tukey's test (p < 0.05). Particle size and material employed for incubation affected iDM and iFDN at the initial periods of incubation (p < 0.05).

A premissa é avaliar a relação do tempo de incubação in situ, tamanho de partículas e tipos de materiais sobre as estimativas das frações indigestíveis da matéria seca (MSi) e da fibra em detergente neutro (FDNi) em alimentos e fezes bovinas. Estudaram-se amostras de farelo de soja, alfafa e fezes de bovinos alimentados com dietas com alto concentrado. As amostras foram processadas em moinho de facas com peneiras de porosidade 0,5 e 1,5 mm para alimentos e 1,5 para fezes, acondicionadas em sacos de F57 (Ankon(r)) e tecido não tecido (100 g m-2) de duas marcas na dimensão 4 × 5 cm. Os materiais foram divididos em dois grupos, com e sem tratamento com acetona e cinco repetições, incubadas no rúmen de uma vaca multípara adaptada à dieta 70:30, volumoso:concentrado, respectivamente, por 240h. Os teores de MSi e FDNi foram avaliados sequencialmente para interpretação das porcentagens de material não digerido, e os dados foram submetidos à análise de variância (Anova, p < 0,05), e as médias comparadas posteriormente pelo teste de Tukey (p < 0,05). Houve efeito do tipo de material utilizado, tamanho de partículas e material incubado sobre as estimativas de MSi e FDNi.

Current paper assesses the relationship between in situ incubation time, particle size and types of materials on estimates of indigestible fractions of dry matter (iDM) and neutral detergent fiber (iNDF) in cattle feed and feces. Samples of soybean meal, alfalfa and feces of cattle fed on high concentrated diets were analyzed. The samples were processed in a Wiley mill, with 0.5 and 1.5 mm porosity for food and 1.5 mm for feces, which were packed in 4 × 5 cm F57 bags (Ankon(r)) and nonwoven fabric (100 g m-2) of two brands. The material was divided into two groups, with and without treatment with acetone, and five replications. Samples of each group were incubated in the rumen of a multiparous cow adapted to a 70:30 diet, forage:concentrate diet, for 240 hours. The iDM and iNDF levels were evaluated sequentially to interpret the percentages of undigested material. Data underwent analysis of variance (ANOVA, p < 0.05) and means were compared by Tukey's test (p < 0.05). Material, size of particles and incubated material affected iDM and iNDF estimates.

The objective was to evaluate the effects of laboratory-silo type and method of silage extract production, respectively, on sugarcane silage fermentation and recovery of fermentation products. Sugarcane was mechanically harvested and ensiled in three different types of laboratory silos (five replicates): 9.7 × 30 cm PVC tubes with tight lids, equipped or unequipped with Bunsen valves, and 20 L plastic buckets with tight lids and Bunsen valves. Three methods were used to produce silage extracts for pH, ethanol, acetic and lactic acids determination: extraction of silage juice by a hydraulic press and production of water extracts using a stomacher or a blender. Total dry matter loss (231 g/kg DM) was not affected by silo type. No interactions between silo type and method of silage extract production were observed for ethanol and organic acids contents in the silages. Interaction between silo type and method of silage extract preparation was detected for pH. Silo type affected ethanol content but did not affect lactic and acetic acids concentration in the silages. Dry matter, crude protein, neutral detergent fiber and ash were not affected by silo type. The method used to produce silage extracts affected the recovery of all fermentation products analyzed in the silages. Recovery of ethanol and acetic acid was higher when silage extracts were produced using a blender. For lactic acid recovery, the hydraulic press method was superior to the other two methods. Silage fermentation pattern is not affected by silo type, but the method used to produce silage extracts and some characteristics of silos affect the recovery of volatile fermentation products.

The objective of this work was to evaluate the yield performance and macronutrient content of rubber extracted from four Hevea brasiliensis clones, under different tapping systems and plant phenological stages. The experiment was carried out in the 2010 and 2011 crop seasons, in a split‑plot randomized complete block design, with four replicates. The main treatments - GT 1, PB 235, IAN 873, and RRIM 600 clones - were allocated in the plots, and the secondary treatments, which were the tapping systems ½S d/2, ½S d/4 ET 2.5%, and ½S d/7 ET 2.5%, were allocated in the subplots. The analyzed variables were natural rubber yield and macronutrient contents. Samples of natural rubber were obtained in the leaf development, mature leaf, and leaf senescence phenological stages. Rubber yield and its macronutrient contents are more influenced by tapping practice than by genetic material in the restrictive phenological stages of foliage.

El objetivo de este trabajo fue evaluar el desempeño productivo y el contenido de macronutrientes del caucho extraído de cuatro clones de Hevea brasiliensis, en diferentes sistemas de sangría y estados fenológicos de las plantas. El experimento fue realizado en los años agrícolas de 2010 y 2011, en diseño experimental de bloques completos al azar, en parcelas subdivididas, con cuatro repeticiones. Los tratamientos principales - clones GT 1, PB 235, IAN 873 e RRIM 600 - fueron ubicados en las parcelas, y los subtratamientos, que fueron los sistemas de sangría ½S d/2, ½S d/4 ET 2,5% y ½S d/7 ET 2,5%, se ubicaron en las subparcelas. Las variables analizadas fueron producción y contenido de macronutrientes. Las muestras fueron obtenidas en los estados fenológicos de brotación foliar, hojas maduras y senescencia foliar. La producción y los contenidos de macronutrientes del caucho son más influenciados por la práctica de sangría que por el material genético en los estados fenológicos más restrictivos para el follaje de caucho.

The objective of this trial was to evaluate chemical additives and a bacterial inoculant on the inhibition of alcoholic fermentation and reduction of losses in sugarcane silages. Treatments were (doses on a fresh forage basis): without additive (control); urea (10 g/kg); urea (5 g/kg) + sodium benzoate (0.5 g/kg); sodium benzoate (1 g/kg); urea + ammonium sulfate in a 9:1 relation (10 g/kg); Lactobacillus buchneri (5 × 10(4) cfu/g). Silages were produced in 10.16- × 30-cm PVC tubes, provided with tight lids adapted with Bunsen valves for gas losses quantification. Minisilos were opened 139 days after ensiling. Ethanol content (227 g/kg dry matter - DM) and total DM loss (30%) were high in the control silage. All additives, except benzoate, decreased ethanol concentration in silages. Inoculation with L. buchneri increased acetic acid content in the silage, resulting in a 41% reduction in ethanol content and the lowest gas loss among treatments (15.2%). There was synergistic effect between additives for the combined use of urea and benzoate. Silage treated with urea + ammonium sulfate has higher content of total digestible nutrients than the silage treated with urea exclusively.

Objetivou-se avaliar os efeitos de esterco bovino, fosfato natural reativo e biotita xisto sobre a fertilidade do solo, a produção e o estado nutricional de Megathyrsus spp. cv. Massai. O experimento foi realizado em condições de campo, em Latossolo Vermelho Amarelo distrófico (Oxisol). O delineamento experimental utilizado foi o de blocos casualizados, com os seguintes tratamentos: três doses de fosfato natural reativo da Argélia, Djebel-Onk (0, 100 e 200 kg ha-1 de P2O5), três doses de biotita xisto (0, 150 e 300 kg ha-1 de K2O) e três doses de esterco bovino (0, 20 e 40 t ha-1). A aplicação de fosfato natural aumentou a produção de matéria seca, enquanto as aplicações de esterco bovino e a biotita xisto não influenciaram esta variável. Os teores de nitrogênio, potássio e magnésio (esterco bovino), fósforo e boro (fosfato natural) e potássio (biotita xisto) nas folhas foram influenciados pelas doses de fertilizante aplicadas. Somente os níveis de fósforo no solo e na planta e os de magnésio e boro na planta apresentam interação com a produção de matéria seca da cultivar Massai.

The objective of this work was to evaluate the effects of cattle manure, reactive natural phosphate and biotite schist on the soil fertility, yield and nutritional status of Megathyrsus spp. cv. Massai. The experiment was conducted under field conditions, in a dystrophic Red Yellow Latosol (Oxisol). It was used a randomized block experimental design with the following treatments: three natural reactive rock phosphate from Algeria (Djebel-Onk) doses (0, 100 and 200 kg ha-1 of P2O5), three biotite schist doses (0, 150 and 300 kg ha-1 of K2O) and three cattle manure doses (0, 20 and 40 t ha-1). The application of natural phosphate increased dry matter yield, however, application of cattle manure and biotite schist did not influence this variable. Foliar levels of nitrogen, potassium and magnesium (cattle manure), phosphorous and boron (natural rock phosphate) and potassium (biotite schist) were influenced by the applied fertilizer doses. Only the levels of phosphorous in the soil and in the plant and levels of magnesium and boron in the plant show interaction with dry matter yield of Massai cultivar.

Determination of Cr(VI) and Cr(III) was studied in soil samples accidentally contaminated with sulphochromic solution. Molecular absorption spectrophotometry based on the diphenylcarbazide method was used for the determination of Cr(VI) after its alkaline extraction. The total chromium concentration was determined using ICP OES. The quantification of Cr(III) was accomplished by subtracting the Cr(VI) concentration from the total chromium concentration. Regardless of the known contamination of the soil samples by sulphochromic solution, concentrations of Cr(VI) were below the detection limit. Addition and recovery experiments for Cr(VI) in soil samples with and without organic matter indicated its influence on the reduction of Cr(VI) to Cr(III).

RESUMO - O objetivo deste trabalho foi avaliar o efeito de um inoculante bacteriano comercial, contendo Lactobacillus plantarum, Streptococcus faecium e Pediococcus acidactili, sobre a qualidade da silagem e perda de matéria seca (MS) durante a ensilagem de sorgo (Sorghum bicolor L. Moench). Os tratamentos foram constituídos por dois tipos de silagem de sorgo duplo-propósito colhido no estádio farináceo: sem (controle) e com inoculante; três posições dentro de cada silo (região do terço inicial, região central e do terço final), correspondendo a três períodos de coleta (52, 65 e 71 dias de fermentação) e três repetições em cada posição. Cada repetição foi constituída por um saco de tela plástica de malha fina, contendo aproximadamente 4 kg de forragem, sendo a parcela representada por uma amostra de aproximadamente 1 kg de forragem. A silagem com inoculante apresentou menor teor de cinza (matéria mineral), nitrogênio amoniacal e ácido láctico e níveis mais elevados de fibra em detergente neutro e fibra em detergente ácido. A silagem com inoculante não diferiu do controle em relação ao pH, à proteína bruta, energia bruta e porcentagem de perda da MS.

ABSTRACT - The objective of this work was to evaluate the effect of a commercial bacterial inoculant containing Lactobacillus plantarum, Streptococcus faecium and Pediococcus acidactili on the quality and dry matter (DM) loss of sorghum (Sorghum bicolor L. Moench) during the ensilage process. The treatments were constituted of two types dual propose sorghum silage harvested at the dough stage: without (control) and with inoculant; three positions in each silo (front, middle and back regions) corresponding to three periods of collection (52, 65 and 71 days of fermentation) and three replicates in side each position. Each replicate was constituted of a fine meshed nylon bag with 4 kg of forage containing 1 kg of forage approximately. The inoculated silage had lower ash (mineral matter) percentage, ammonia nitrogen and lactic acid, higher content of neutral detergent fiber and acid detergent fiber. The silage with inoculant did not differ from the control in relation to the pH, crude protein, gross energy and percentage of DM loss.