EFECTO DEL TRATAMIENTO SOBRE EL VALOR NUTRITIVO DE LA PAJA TRATADA POR UREA (EFFECT OF THE TREATMENT ABOUT THE NUTRITIOUS VALUE OF UREA TREATED BARLEY STRAW)

Resumen
El experimento se ha diseñado, con el fin de determinar el efecto de un tratamiento con urea (6 p.100 de la MS) sobre la composición química y componentes nitrogenados de la paja de cebada, en función del nivel inicial de humedad (20 p.100, 30 p.100 y 40 p.100) y la temperatura de conservación (25°C y 35°C). El tratamiento afectó fundamentalmente al contenido de FND de la paja, que disminuye en general como consecuencia de una solubilización de la hemicelulosa, que es mayor al aumentar la temperatura del tratamiento y la humedad inicial de la paja, llegando a solubilizarse un 25 p.100 de la hemicelulosa a 35°C y un 40 p.100 de humedad. La fibra ácido detergente también aumenta con la humedad y la temperatura. El contenido de proteína bruta también fue modificado sustancialmente por los tratamientos, disminuyendo en todos los casos con la humedad y aumentando con la temperatura, como consecuencia de la transformación de la urea en amoníaco favorecida por ambos factores. La urea residual ha sido afectada fundamentalmente por la humedad, siendo muy elevada para el 20 p.100 de humedad y haciéndose casi nula para el 40. Un contenido inicial de humedad elevado (próximo al 40 p.100) es entonces necesario para conseguir que la urea sea hidrolizada en su totalidad, lo que favorece la solubilización de la hemicelulosa. La mejora es aún mayor cuando la hidrólisis se realiza a temperatura elevada (35oC). Estas condiciones son las que dan lugar también a una mayor retención de nitrógeno en función del aportado.
Abstract
The experience has been designed with the purpose of determining in the barley straw, the effect that a treatment by means of urea (6 percent of the DM) would have on its chemical composition and its component nitrogenous when the conditions of the treatment were varied the initial level of humidity (20 percent, 30 percent and 40 percent) and the conservation temperature (25°C and 35°C). Regarding the chemical composition the treatment affects fundamentally to the content in FND of the straw that diminishes in general as consequence of a solubility of the hemicelulosa that is bigger as much as adult is the temperature of the treatment and as much as adult is the initial humidity of the straw, arriving to solubility 25 percent of the hemicelulosa for the barley straw to 35°C and 40 percent of humidity. The content in gross protein is the other component that is modified substantially by the treatments, diminishing in all the cases with the humidity and increasing with the temperature like consequence of the transformation of the urea in ammonia that is favored by both factors. The fiber acid detergent, increases with the humidity and with the temperature, being reached the values but high for 40 percent of humidity and for both temperatures. The effect on the fraction nitrogenous depends fundamentally on the urea that has reacted under the different conditions of the treatment. The residual urea has been affected fundamentally by the humidity, being very high for 20 percent of humidity and being made almost null for 40 percent. The temperature has a very small effect although when being increased makes increase the urea for the barley straw. A high initial content of humidity (next to 40 percent) it is then necessary to get that the urea is hidrolized in its entirety what favors the solubility of the hemicelulasa improving the digestibility. The improvement is even bigger when the hidrolise is carried out to high temperature (35°C). These conditions are those that also give place to a bigger nitrogen retention in function of the one contributed.