Cinética de degradação in vitro da aveia IAPAR 126 sob diferentes períodos de descanso

Abstract

The diet formulation systems require the measurements of food among these forages are the most widely used food source for ruminants. The kinetics of degradation are important because they describe the addition of digestion characterize the intrinsic properties of food which limit the availability to the ruminant. The objective of this study was to determine the kinetics of degradation of oat IAPAR 126 under different rest periods by the method of gas production. The study was conducted at theUniversidade Tecnológica Federal do Paraná, Campus Dois Vizinhos, located on the third plateau of Paraná. We used two cuts of forage during the vegetative cycle testing four rest periods which are: 14, 2, 28 and 35 days distributed in four randomized blocks. The readings of pressure and volume were taken at 1, 2, 3, 6, 8, 10, 12, 16, 20, 24, 30, 36, 48, 72, and 96 hours of incubation. The measurements of gas were obtained by means of a non-automated, comprising a manometer connected to a vessel communicating system for reading pressure and volume respectively. The interpretations of the kinetic parameters of degradation were analyzed by logistic model bicompartmental: V (t) = (V1/ (1 exp (2 -4*k1*(T-ʎ))) (V2/ (1 exp (2 -4*k2*(T-ʎ))). The adjusted parameters in the model were estimated by logistic bicompartmental NLIN procedure of SAS ® application (version 9) with the Marquardt method. To determine whether there was influence of the treatments onthe values of the parameters we used repeated measures analysis with a mixed model methodology using the PROC MIXED procedure of SAS (version 9) and restricted maximum likelihood (REML) as the estimation method. For modeling the variance and covariance matrix were tested four structures: VC, CS, AR (1) and UN. The relationship between pressure and volume of gas was linear and highly significant (P<0.0001). The use of the logistic model bicompartmental allowed obtaining estimates of parameters consistent with the existing theory. The volumes of gas produced by the degradation of non-fiber carbohydrates (V1) and the fiber (V2) were not influenced by rest days. The degradation rate observed for the non-fiber carbohydrates (k1) increased with advancing plant maturity. As the rate of degradation of the fiber (k2), there was no statistical difference between the different treatments. The time of colonization of the substrate by rumen microorganisms (ʎ) did not differ as a function of days of rest. Fermentation of oats at 48 hours of incubation was influenced (P=0.0009) negatively with the advent of plant maturity.