Abstract

LA O  LEON, Orestes et al. Age effect on the in vitro fermentation capacity and on the in situ dynamic of ruminal degradation of Tithonia diversifolia. Zootecnia Trop. [online]. 2008, vol.26, n.3, pp.243-247. ISSN 0798-7269.

An experiment was conducted with Tithonia diversifolia, at different harvesting ages to determine the effect of age on the in vitro fermentation capacity and on the in situ dry matter dynamic of ruminal degradation. For the in vitro study there were utilized incubation times of 0, 3, 6, 12, 24, 48, 72 and 96 h of fermentation, meanwhile for the in situ study, samplings were taken at 6, 12, 36, 48, and 72 h. Fermentation data were adjusted to the exponential model. In vitro kinetics performance showed an increment in the gas production as samples were exposed to attack of the microorganisms with values of 36.03, 32.12, 34.12, 37.11 and 34.7 at 98h for 30, 50, 70, 90, and 110 d of growing respectively, with higher values of gas production at 90 h. Dynamics of in situ dry matter ruminal degradation showed an asymptotic type of progressive increment, meanwhile data for dry matter effective degradability for different constants of ruminal turnover rate (k = 0.03, 0.044, and 0.05 %/h) had a similar performance in all nutrients, varying between 46.39-60.46, 42.40-56.23, 41.75-53.86, and 41.18-53.31 for 30, 50, 70, and 90d of growing, respectively. Results obtained suggested, according to the in vitro and in situ studies, that ages between 70 and 90d allow a great use of the nutrients by the animal. It is necessary to perform in vivo studies to confirm this hypothesis, considering inclusion of different levels of the plant in the diet of ruminants.

Keywords : nutritive value; in vitro fermentation potential; gas production; ruminal in situ degradation; Tithonia diversifolia.

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