Evaluation of coffee grain (Coffea arabica L.) hulls and dehydrated pulp in vitro degradability using the gas production technique

The experiment was conducted utilizing hull and dehydrated pulp of coffee cultivars Catuai, Rubi and Mundo Novo. Pulp was obtained by moist pulping in a mechanical pulper and dried up to 13% moisture. Materials were stored in raffia bags in ventilated, moistureless environment and sun sampled every 90 days. 400 mg of each sample (DM and NDF) were incubated in vitro in triplicates in a water bath at 39degreesC. The cumulative gas production was obtained at 1,2,3,4,5,5,12, 18, 24, 30, 36 48 60 and 72 hours. The kinetics of the cumulative gas output for DM and NDF as determined using the model V-t = V-t1/(1 + exp(2 + 4m(L - T))) and SDN by the model V-t = V-t1 x (1 - exp(-m x T)). Cumulative gas production of the SDN fraction was obtained by the difference between the cumulative production from DM and NDF. Storage of hull and dehydrated coffee pulp improved the degradation rate, reduced fibrous and undegradable fractions, releasing soluble sugars for the ruminal flora. For coffee hulls of all cultivars, the maximum fermentation contribution of SDN and NDF took place respectively around 24 and 48 hours. The maximum gas production in pulp DM occurred between 48 and 60 hours in all cultivars and was a consequence of the maximum gas production by the NDF fraction, which peaked around 60 hours. Long colonization period may be a limitation to the use of hull and dehydrated coffee pulp in ruminant feeding, impairing feed utilization by ruminal microorganisms due to the rapid passage by the rumen.