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Revista Ciencias Técnicas Agropecuarias
versión On-line ISSN 2071-0054
Rev Cie Téc Agr vol.21 no.3 San José de las Lajas jul.-set. 2012
NOTA TÉCNICA
Changes in aminic nitrogen of silages
Cambios en nitrógeno amínico de ensilados
Prof. Danilo Revuelta Llano
Universidad de Granma, Facultad de Ciencias Técnicas, Departamento de Ciencias Básicas, Bayamo, Cuba,
ABSTRACT
This paper investigated quantitative changes of aminic nitrogen as a important protein breakdown parameter in laboratory scale silages.The experiments were performed from November to April (rainy season) of 2010 year at the Agronomy Faculty of Chianga (13km from Huambo City) in Angola. It showed that increasing aminic nitrogen below threefold value is a reasonable guide for optimal protein preservation in silages. The potenciometric formol method for aminic nitrogen determination is simple, rapid and economic. It is recommended this chemical analysis for routine control of silage quality.
Key words: aminic nitrogen, protein degradation, laboratory silage, postharvest.
RESUMEN
Se investigaron los cambios cuantitativos de nitrógeno amínico, como un importante parámetro de la degradación de la proteína, en ensilados a escala de laboratorio. Los experimentos se desarrollaron en la época de lluvias, desde noviembre hasta abril del año 2010, en la facultad de Agronomía de Chianga, localizada a
Palabras clave: nitrógeno amínico, degradación de proteína, ensilados de laboratorio, postcosecha.
INTRODUCTION
Based on a combination of energy and digestible protein per hectare, Santana et al. (2010), recommended harvest age of napier grass during rainy season within an interval of 54 to 60 days of regrowth. Recycling by-products of food industry as silages is one important technological alternative to prevent environmental pollution (Revuelta, 2000; Revueltal et al., 2008). Sustainability of animal agriculture requires efficient use of feed N so as to prevent its release to the environment. Therefore, there is an urgent need to explore different ways that can potentially increase the efficiency of N utilization to make the livestock industry profitable and a friendly environment operation. High protein degradability of silages decreases their usage as an efficient protein sources. Knowledge of free amino acids content during anaerobic storage is very important in understanding biological processes of protein transformation in food technology of conservation. In vitro proteolyses assays indicated that there is a potential inhibition of proteases when specific o-diphenols are supplied to grass extracts (Marita, Hatfield & Brink, 2010). Thus, the chemical composition of crude protein indicated that minimal improvement of true protein fraction in silages has a great economic effect in the animal production (Jones, 2001). Thus, a modified ninhydrin colorimetric assay was evaluated for quantification of free amino acids in silage extract (Winters et al., 2002). Other alternative for this analysis is the determination of aminic nitrogen content using the formol method (Chechetkin et al., 1984, USP XXIV, 2000, & Morris et al., 2002). The aminic nitrogen represents nitrogen of polypeptides, free amino acids and proteins. The principle of formol method for the aminic nitrogen determination is based on the following chemical reactions:
RESULTS AND DISCUSSION
Other influencing chemical parameters for protein preservation are poliphenols and tannins contents (Kofahl, 2008).
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Recibido: 15 de marzo de 2011.
Aprobado: 19 de mayo de 2012.
Danilo Revuelta Llano, Universidad de Granma, Facultad de Ciencias Técnicas, Departamento de Ciencias Básicas, Carretera de Manzanillo km. 17 ½, Bayamo, Provincia Granma, Cuba, Correo electrónico: drevueltal@udg.co.cu