This study used a total of 2020 Colombian forage resources of three families (Grass forages, legume forages, and other forage plants) to develop near infrared spectroscopy calibrations for predicting the nutritional value. Spectra were collected at 2 nm increments using a scanning visible/near infrared spectrometer. The reference data used for each forage were crude protein, crude ash, neutral detergent fiber, acid detergent fiber, acid detergent lignin, measured according to the Association of Official Analytical Chemists. Two chemometric tools for developing near infrared spectroscopy prediction models were compared: the GLOBAL modified partial least squares, and the calibration strategy known as LOCAL. The LOCAL procedure is designed to select, from a large database, samples with spectra resembling the sample being analyzed. Selected samples were used as calibration sets after one-tenth of the samples were selected for validation from each database. Predictions of nutrition indicators in validation samples using generic and specific calibrations were compared with both GLOBAL and LOCAL procedures. For all predicted forages, LOCAL resulted in a significant improvement in both standard error of prediction and bias values compared with GLOBAL. Determination coefficient values (r 2) also improved using the LOCAL algorithm, exceeding 0.9 for most forage sets. LOCAL calibration was then used with only one database (n 2020) comprising all the forage samples and SEP and r 2 were similar to those obtained in the three databases using LOCAL algorithm. Therefore, LOCAL can accurately predict the composition of different forages using only one database, and could offer a practical way to develop robust equations taking into account the biodiversity of Colombian forages.
Essential oils have been proposed as alternatives to antibiotic use in food animal production. This study evaluated 3 chemotypes of the Origanum genus, containing varying amounts of secondary metabolites carvacrol, thymol, and sabinene, in the broiler chicken diet. Aerial parts of Origanum vulgare L. (OL), O. vulgare L. ssp. hirtum (OH), and O. majorana (OM) were collected from a greenhouse located in the high altitude Sabana de Bogotá (Savanna of Bogotá) and O. vulgare L. ssp. hirtum (OG) produced and ground in Greece. Oregano essential oils (OEO) from these plants were obtained by steam distillation and analyzed by gas chromatography coupled to a mass spectrometer. Six treatments were evaluated: 200 mg/kg of OEO from OH, OL, and OM, 50 mg/kg of OEO from OG, 500 mg/kg of chlortetracycline, and without additives. Broiler chicks were maintained at 2,600 m above sea level, placed in brooder cages under a completely randomized design. Template DNA was isolated from duodenal, jejunal, ileal, and cecal contents in each group and bacterial 16S rDNA patterns were analyzed by denaturing gradient gel electrophoresis. Dendrograms of denaturing gradient gel electrophoresis band patterns revealed 2 main clusters, OEO-treated chicks and nontreated control chicks, in each intestinal segment. Band patterns from different gut compartments revealed major bacterial population shifts in the foregut (duodenum, jejunum, and ileum) compared with the hindgut (cecum and colon) at all ages evaluated (P < 0.05). The OEO groups showed less shift (62.7% similarity coefficient) between these 2 compartments versus the control groups (53.7% similarity coefficient). A reduction of 59% in mortality from ascites was seen in additive-supplemented groups compared with the control group. This study represents the first work to evaluate the effects of the 3 main chemotypes of Origanum genus in broilers.
rev Med vet Zoot. 64(3), septiembre-diciembre 2017: 52-77 ____________________________________ investigación 52Pérez-López y Afanador-Téllez. Comportamiento agronómico y nutricional de genotipos de Brachiaria spp. manejados con fertilización nitrogenada, solos y asociados con... rEsumEN La altillanura colombiana es una microrregión que tipifica un tipo de producción bovina extensiva que requiere el uso de gramíneas adaptadas que respondan a la fertilización nitrogenada para mejorar el rendimiento y la calidad nutricional de las praderas, a fin de intensificar los sistemas de producción ganaderos. el estudio se desarrolló en la sede Taluma de Corpoica, ubicada a 04°34´25" Oeste y 71°20´10'' norte en el municipio de Puerto López (Meta, Colombia), en condiciones de clima y suelo representativos de la altillanura colombiana. el objetivo del estudio fue determinar el comportamiento agronómico y nutricional de los genotipos de Brachiaria brizantha CiaT 16315, 16467, 26990, 26124, 6387 y el control Mulato ii manejados con fertilización nitrogenada sola y asociada con la leguminosa Kudzú (Pueraria phaseoloides). se utilizó un diseño de bloques completos al azar con arreglo en franjas divididas, en donde la parcela correspondió a la gramínea forrajera y la franja al nivel de fertilización nitrogenada (n46, n92 y P. phaseoloides + n46). Los genotipos fueron evaluados durante 90 días, tanto en época seca, como lluviosa. Las accesiones con mayor producción de biomasa (p < 0,001) fueron B. brizantha CiaT 16315 (2.040 kgMs.ha ). el tratamiento de la gramínea + n92 (kgn.ha -1 ) presentó valores significativamente (p < 0,001) superiores de PC (9,55%) y degradabilidad del forraje (65,7%), y los menores contenidos de materia seca (37,05%), Fdn (61,97%) y Fda (30,55%) en relación con las gramíneas fertilizadas con 46 kgn.ha -1 y las gramíneas asociadas con Kudzú y fertilizadas con 46 kgn.ha -1 . Por mayor contenido de PC (p < 0,001), se destacaron los materiales B. brizantha CiaT 16315 (8,34%) y CiaT 26124 (8,06%) que no presentaron diferencias significativas con el pasto Mulato ii (8,18%). Los resultados demostraron la importancia de la fertilización nitrogenada para mejorar la producción y calidad nutricional de las praderas de B. brizantha.
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