Degradabilidade “in situ” do feno e da silagem de capim Piatã em diferentes cultivos

Abstract

The objective of this study was to evaluate the rumen degradability of hay and silage of the grass UrochloaBrizantha cv. Piatã in monoculture and simultaneous cultivation with maize. TNT bags inside tulle bags, measuring 20x20 tied with nylon line, were introduced directly into the rumenin descending order of 96, 72, 48, 36, 24, 12, 9, 6, 3, and 0 hours, as each tulle bag containing 48 TNT bags, in triplicates in the animal and incubation time.To estimate theparametersof ruminalkinetics, an asymptotic of first orderwas used: PD = a+b (1-e-ct), in which PD = potential degradability; a = soluble fraction; b = fraction potentially degradable of the insoluble fraction; c = fraction degradation rate; t = incubation time. Partially, all the evaluated feeds showed low effective degradability regarding the exposure time to the ruminal environment being necessary a higher time to reach the maximum degradation potential of each feed.The evaluated feed in this study had low to average potential degradability (NDF and DM) an average soluble fraction and degradation ratio. The slowcolonization time influenced to this low degradation of the feeds. The silage with suppression presented thegreater valueforeffective degradability(48% to NDF) in a less time of remains exposure in the rumen.