Cinética de degradação ruminal de cultivar de aveia branca (Avena sativa L.) sob diferentes níveis de adubação nitrogenada

Abstract

When it is formulating diets, the knowledge about the chemical composition and degradation of constituents is essential to meet the nutritional requirements of ruminants. In this sense the kinetic parameters aid in the description of digestion and understanding of the same. This study aimed to identify and evaluate the kinetics of ruminal degradation through technical gas production. With the aid of pressure gauges and pipette (25 ml) was measured pressure and volume of gas produced. The set time of reading and evaluation was performed fractionated on 1, 2, 3, 6, 8, 10, 12, 16, 20, 24, 30, 36, 48, 72, 96 hours of incubation. Fieldwork was conducted at the Federal Technological University of Paraná -Campus Dois Vizinhos, Culture Experimental Station Annual April-September 2013. Avena sativa L., variety IPR126 was evaluated. After implantation , we performed a cut of standardization to achieve approximately 25 cm in height , and subsequent sections were performed every 21 days , maintaining a height of regrowth to 10 cm above the ground. Were subdivided into areas of 6m2 , which received doses of 0 , 60 , 120 and 240 kg N / ha . Interpretations of kinetic parameters of degradation were analyzed by two-compartment logistic model : V ( t ) = ( V1 / ( 1 + exp ( k1 * 2-4 * (T -ʎ) ) ) + ( V2 / ( 1 + exp ( 2-4 * k2 * (T -ʎ) ) ) . parameters adjusted in two-compartment model were estimated by logistic NLIN procedure of SAS ® software ( version 9 ) with the method of Marquardt . To determine whether there was influence of treatments on the values of the parameters the analysis of repeated measurements with mixed methodology using PROC MIXED of SAS( version 9 ) and restricted maximum likelihood ( REML ) as the method of estimation models procedure was used . VC , CS , AR ( 1 ) and UN: For modeling the variance and covariance matrix of four structures were tested . The relationship between pressure and volume of gas was linear and highly significant ( P < 0.0001). The use of the logistic model bicompartimental allowed to obtain estimates of parameters consistent with the theory applied . The volumes of gas produced by the degradation of non-fiber carbohydrates ( V1 ) and the fiber ( V2),were not affected by N levels. The rate of degradation found for NFC ( k1 ) decreased with theaddition of higher doses of N.The degradation rate of the CF ( k2) , there was no statistical difference between the different treatments . The time of colonization of the substrate by rumen microorganisms ( ʎ) increased with the addition of N.