Kinetics and degradability of marandu grass fertilized with nitrogen doses

Abstract

Nitrogen fertilization alters the bromatological composition of forage, potentially influencing its degradation kinetics. Therefore, this study aimed to assess the extent to which nitrogen fertilization affects the degradability and degradation kinetics of Urochloa brizantha cv. Marandu. The experiment was conducted at the experimental farm of the Federal University of Mato Grosso, in Santo Antônio do Leverger, using a completely randomized design with five nitrogen treatments (0, 25, 50, 75, and 100 kg ha⁻¹) and seven replicates. Forage samples were collected during two rainy seasons. Degradability and degradation kinetics were evaluated using the in vitro incubation technique. In vitro incubations were performed using amber vials, where 500 mg of forage were incubated with McDougal solution and ruminal inoculum for 72 h. Gas volume decreased with increasing nitrogen doses. Although dry matter degradability also showed a linear decreasing trend, the reduction was not significant. Lag time showed a quadratic response, with the 50 kg ha⁻¹ dose resulting in the longest colonization time. The degradation rate increased with higher nitrogen levels. Therefore, nitrogen fertilization influences the degradation kinetics and degradability of Marandu grass.