Hernan Maldonado Vasquez

Composição Bromatológica, Disponibilidade de Forragem e Índice de Área Foliar de 17 Genótipos de Capim-Elefante (Pennisetum purpureum Schum.) sob Pastejo, em Campos dos Goytacazes, RJ

The assay was conducted from October 1998 to January 1999 in the cropgrass section of the Universidade Estadual do Norte Fluminense in Campos dos Goytacazes, RJ. The levels of crude protein, neutral detergent fiber, acid detergent fiber, the forage yield and the leaf area index (LAI) were evaluated in 17 genotypes of elephantgrass (Pennisetum purpureum, Schum.), fifteen new clones of elephantgrass: CNPGL 91-19-1, CNPGL 91-10-5, CNPGL 91-27-5, CNPGL 91-02-5, CNPGL 91-01-2, CNPGL 91-13-2, CNPGL 91-25-3, CNPGL 91-10-2, CNPGL 91-02-4, CNPGL 91-11-2, CNPGL 91-34-1, CNPGL 91-27-1, CNPGL 91-28-1, CNPGL 91-06-3, CNPGL 91-17-5 and two cultivars, MINEIRO and TAIWAN A-146, from the BAGCE of the Dairy Cattle Research Center - EMBRAPA. The elephantgrasses were submited to grazing, in the rainy season, by lots of 10 to 13 dry cows with average live weight of 500 kg, during a period of 1 to 2 days. The genotypes CNPGL 91-01-2, CNPGL 91-10-2, CNPGL 91-25-3, CNPGL 91-10-5 and CNPGL 91-27-5 showed greatest percentage of crude protein, and smaller values of neutral detergent fiber and acid detergent fiber. In general, the chemical composition was negatively affected by period after period of grazing. No differences were found in the forage dry matter yield of the genotypes. The genotypes CNPGL 91-02-5 and CNPGL 91-11-2 presented utmost LAI of 7.08 and 6.67, respectively. Differences were found from the first to other grazing periods, as to dry matter production as to leaf area index.

Mineral composition of pastures in the North and Northwest regions of Rio de Janeiro State. 2. Manganese, iron, zinc, copper, cobalt, molybdenum and lead.

ABSTRACT ¾ The contents of Mn, Fe, Zn, Cu, Co, Mo and Pb of soil, predominant forage in the pastures and water, were studied in the North and Northwest regions of Rio de Janeiro State, during the dry (June-July) and rainy (December-January) seasons. Samples of soil, forage and water were collected in 12 different points of the regions, in predominant grazing areas, as determined by satellite photograph and according to different soil characteristics. The mineral contents of the sample extracts were determined by spectrometry, on a inductive plasma emission source apparatus. In both seasons it was found low levels of Cu and Zn in forage samples and the mineral contents of forages varied with the type of soil. The levels of Fe and Mn were higher than the requirements and deficiencies of Cu and Zn were found. The cobalt contents of forages were higher than cattle requirements. The analyzed microelements in water usually were very low when compared with the safety levels. It was concluded that the mineral contents in the water analyzed samples were within the safety margin for domestic animals.

Óxido de cromo e n-alcanos na estimativa do consumo de forragem de vacas em lactação em condições de pastejo

Foram avaliadas as tecnicas do oxido de cromo/digestibilidade in vitro e dos pares de n-alcanos (C31:C32 e C33:C32) na estimativa do consumo de materia seca (CMS) por vacas Holandes x Zebu em lactacao em pastagem de capim-elefante cv. Napier. As extrusas foram obtidas utilizando-se uma vaca com fistula esofagica. Realizaram-se coletas de fezes duas vezes ao dia, diretamente no reto dos animais, durante nove dias em cada periodo experimental. O delineamento utilizado foi o de blocos casualizados, em esquema de parcelas divididas. Ambos os pares de n-alcanos possibilitaram estimativas de consumos semelhantes, independentemente do horario de coleta (manha e tarde), sugerindo que uma unica coleta de fezes por dia seria suficiente. Quando o estudo foi realizado utilizando-se o valor medio das duas coletas, todas as metodologias diferiram entre si. O Cr2O3/DIVMS forneceu valores de CMS que podem ser considerados mais adequados, pois foram mais proximos daqueles estimados para forragem consumivel (2,6% PV) e dos valores das tabelas de exigencias do NRC (2001) (2,7% PV). Alem disso, essa tecnica apresentou vantagens quanto a simplicidade dos procedimentos analiticos e ao baixo custo.

Efeito da amonização sobre a composição, a retenção de nitrogênio e a conservação do bagaço e da ponta de cana-de-açúcar

Foram estudadas a composicao bromatologica e a conservacao de subprodutos da cana-de-acucar tratados com 0, 1, 2 e 4% (N-amonia na materia seca) nas formas de amonia anidra, ureia e sulfato de amonio, em arranjo fatorial e delineamento inteiramente casualizado. Nao houve alteracao no teor de materia seca do bagaco, em funcao das fontes de amonia. As fontes de amonia promoveram decrescimo no teor de fibra em detergente neutro do bagaco, entretanto, so com o sulfato de amonia a ponta apresentou tal comportamento. Houve reducao no teor de hemicelulose dos subprodutos tratados com ureia, em funcao dos niveis de amonia. A amonizacao com sulfato de amonio reduziu o teor de fibra em detergente acido, principalmente, da ponta. Houve decrescimo no teor de celulose do bagaco tratado com amonia anidra. Os tratamentos resultaram em aumento no teor de proteina bruta de ambos subprodutos, em funcao dos niveis de amonia. O sulfato de amonio promoveu reducao no teor de nitrogenio insoluvel em detergente acido e maior retencao de nitrogenio nos dois subprodutos. Na maioria dos tratamentos, os periodos apos abertura dos silos nao alteraram o teor de nitrogenio total dos subprodutos. Os beneficios promovidos pelos tratamentos persistiram ate o 48o dia para o bagaco e ate o 24o dia para a ponta.

Production and chemical composition of furachão grass (Panicum repens L.) under fertilization and different cutting ages

The objective of this work was to evaluate the dry matter (DM) yield and chemical composition of furachao grass (Panicum repens L.) at different cutting ages (15, 30, 45, 60 and 75 days), with and without fertilization. For the yield analysis and chemical aanalysis composition, a completely randomized block design in a 5 x 2 factorial arrangement (cutting ages and fertilization levels), with three replicates, was used. Fertilization increased DM produced and reduction in the DM contents. The crude protein (CP) contents decreased as the cutting ages increased. At 60 days, productions of 541,87 kg/ha CP and 5343.92 kg/ha DM and average neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents of 69.7 and basis 34.25% in DM respectively were observed. The cutting ages affected the NDF and ADF average contents, but fertilization did not affect NDF contents. At 60 days of age the mean NDF and ADF contents were 69,70% e 34,25% on DM basis, respectively. The Ca contents were not affected by fertilization, with mean value of 0.13% in DM basis, and increased with the cutting age. The P contents reduced as the cutting ages of grass increased and the highest mean value was 0.22% on DM basis, in the without fertilization condition.

Composição bromatológica e fracionamento de carboidratos e proteínas de aveia-preta e triticale sob corte e pastejo

Black-oat (Avena strigosa Schreb.) cv. EMBRAPA 29 and Triticale (X triticosecale Wittmack) cv. IAC 3 were studied under harvest or grazing every 30 d, in three planting seasons (April, May and June), in order to evaluate the bromatological composition under Northern Rio de Janeiro State conditions. The experiment was done in a factorial arrangement 2 × 2 × 3, in randomized block design with three replicates, being the factors: grass, systems and planting season. The dry matter (DM) concentration differed between species and cutting systems, with Triticale showing higher DM under grazing; however there were no differences within species in relation to planting seasons. Significant effects were found between factors and/or its interactions on the levels of neutral detergent fiber (NDF), NDF free of ash and crude protein (NDFacp) and lignin, with higher NDF for Triticale planted in April. Total carbohydrate concentration (%TCHO in DM) did not vary among species and cutting systems, however slightly higher concentrations were found on April, except for Triticale under grazing system; average %TCHO was 77.83% in DM. From this total (%TCHO in DM), 25.5 and 19.20% in the Triticale and in Black-oat, respectively, were composed by non fiber carbohydrate (%NFC in TC). The B2 fraction (%B2 in TC) varied only among planting periods in Triticale under harvest system, ranging from 45.32 to 49.13%, respectively, for April and June. The protein fractionation showed high protein solubility in forage DM, but statistical differences were found only among planting periods for the soluble protein fractions in neutral detergent (fractions A+B1+B2). Considering the average CP value obtained and its availability it is possible to point out these forages as excellent protein sources.

Avaliação nutricional de pastagens de capim-elefante e capim-mombaça sob manejo rotacionado em diferentes períodos de ocupação

Qualitative assessment of elephantgrass (Pennisetum purpureum, Schum. cv. Napier) and mombacagrass (Panicum maximum, cv. Mombaca) pastures under rotational stocking was performed using the esophageal extrusa technique. Samples of esophageal extrusa were taken at the third, second and first days of the grazing period. The following analyses were determined: DM, CP, EE, OM, lignin (LIG), NDF, ADF, in vitro dry matter digestibility (IVDMD), lag time and degradation rate of carbohydrates, and fractions of the carbohydrates and nitrogenous compounds. The average composition of extrusa samples as a function of the days under grazing were compared through orthogonal contrasts, with subsequent adjustment of regression equations. For IVDMD and LIG, differences were observed just for the mombacagrass. For this species, an increase of 2.57 percentual points in the indigestible fraction (fraction C) and a reduction of 3.23 percentual points in the potential degradable fraction (B2) of carbohydrates were observed. For the kinetics of degradation, it was found difference just for the mombacagrass, showing linear reduction in the rate of degradation of the fibrous carbohydrates. Both the acid detergent insoluble protein fraction and the protein degradable fraction of elephantgrass and mombacagrass showed linear decrease with increasing grazing period.

Cinética da degradação ruminal dos carboidratos de quatro gramíneas tropicais em diferentes idades de corte e doses de adubação nitrogenada: técnica de produção de gases

The objective of this experiment was to evaluate the effects of levels 0, 100, 200, 300 and 400 kg of nitrogen/ha and cutting ages of 28, 42, 56 and 70 days on the kinetic parameters of ruminal degradation of carbohydrate of the following tropical forages: Setaria grass (Setaria anceps Stapf), Limpo grass (Hemarthria altissima [Poir] Stapf. & Hubbard), California grass (Brachiaria purpurascens [Raddi] Henr.) and Nilo grass (Acroceras macrum Stpaf). The results were submitted to a factor analysis. After reduction and evaluation of the combined variation from the total variables, three factors comprising 86.44% of the total variation were considered, where the first factor (Factor 1) was strongly associated with the gas volume of substrates of slow and rapid digestion, as well as the fractional rate of substrate of rapid degradation (Vf1, Vf2 and k2). The second factor (Factor 2) was associated to the fractional degradation rate of the slow degradable substrate and lag phase (k1 and L) and the third factor (Factor 3) was related to the in vitro dry matter digestibility (IVDMD). Cutting age had an effect on the grass kinetics, where the growth age resulted on reduced IVDMD. No significant responses of the supply of nitrogen fertilizer in relation to the parameters analyzed were found. Due to its high digestibility, the Limpo grass demonstrated to have an outstanding performance when compared to the other grasses.

Análise financeira e de sensibilidade de sistemas de produção de leite em pastagem

An economical analysis of milk production systems was made with lactating cows on Mombaca grass pasture receiving different sources of roughage supplementation during the dry season. The supplementations were: black oat pasture, forage sugarcane with urea and sorghum silage. The economical indicators used were: net present value (NPV) and internal rates of return (IRR). For each production system studied one cash flow was used with their particularities and productive and reproductive performances index, obtained experimentally. The cash flows were built monthly, for a 12 years period and the NPV of the systems were calculated applying discount rates of 6, 8, 10 and 12% a year. At an annual discount rate of 8% all the production systems were financially viable. The invested capital showed annual IRR of 11.91% for black oat pasture, 9.43% for forage sugarcane and 8.46% for sorghum silage. The sensitivity analysis showed that the milk selling price had greatest economic impact on the profitability of the systems.

Produção de matéria seca, composição da massa de forragem e relação lâmina foliar/caule + bainha de aveia-preta e triticale nos sistemas de corte e de pastejo

The winter forage species Black-oat (Avena strigosa Schreb.) cv. EMBRAPA 29 and triticale (X triticosecale Wittmack.) cv. IAC 3, were studied on three planting dates, April (4/21/2004), May (5/20/2004), and June (6/21/2004) in order to evaluate the technical viability of forage produced under harvest and grazing, in the Northern Region of Rio de Janeiro State. DM production was greater for the harvest system when planted in May, where Black-oat produced 2,317.48 kg DM/ha and triticale 2,128.30 kg DM/ha, compared to 1,169.42 e 678.31 kg MS/ha for black oat and triticale under grazing, respectively. Climatic conditions by the onset of the first cut/grazing anticipated the physiological cycle of these crops, reducing the production potential by decreasing the germination-blooming period and increasing the percentage of stem and inflorescences in the forage mass. The forage mass was composed by 34% of leaf blade, 31.08% stem, 24.56% of inflorescences, and 10.35% of dead material. Black oat showed greater stem + sheath proportion. Black oat species planted in June showed higher leaf blade/stem + sheath ratio, due to the initial stage when plants were submitted to the first evaluation. Despite the higher contribution of inflorescences, triticale species presented a higher leaf blade/stem + sheath ratio, however with no significant difference among treatments. The best planting time for triticale is April, while that for the Black-oat, May/June, both under the cutting system.