[Chemical compounds and kinects of in vitro ruminal degradation of white oats URS Guapa under distinct levels of nitrogen fertilization]

ABSTRACT

Doses of Nitrogen were evaluated: 0, 60, 120 and 240kg ha^-1 on the chemical composition and rumen degradation kinetics of white oats obtained from two consecutive years (2013-2014). For nutritional characterization the following parameters were analyzed: dry matter; ash, crude protein, ethereal extract, neutral detergent fiber, lignin, soluble carbohydrates and insoluble acid detergent protein. No effect of nitrogen fertilization was observed on the variables analyzed in any of the growing years. The nutritional variables were influenced by environmental factors that occurred in the respective experimental periods and the parameters of ruminal degradation kinetics corresponded to the effects in these compounds. In year 2013, higher values were observed for the variables crude protein, ash, insoluble acid detergent protein, soluble CHO and no fibrous carbohydrates, resulting in higher values also for the in vitro gas production kinetics, Vf₁ and k₂. Nutritional contents in 2014 tended to higher levels of NDF, lignin and total carbohydrates, and higher values for the parameters Vf₂ and L. The parameter k₁ was not significant in any of the experimental periods evaluated. In 2014 the forage has its nutritive value negatively influenced by the delay in sowing and the periods of water restriction combined with higher temperatures.

Keywords:
carbohydrates; degradation; nitrogen