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In order to determine the effect of three collections of Tithonia diversifolia (mv-12, mv-14 and mv-17), collected in the eastern region of Cuba, on the ruminal microbial population of cattle, an experiment under in vitro conditions was developed. The control treatments with Cynodon nlemfuensis (star grass) were compared: star grass + mv-12; star grass + mv-14 and star grass + mv-17. The three collections were included at a rate of 20 % of the dry matter. The crude protein content was 19-23 % of the dry matter. With the materials mv-14 and mv-17 higher populations of cellulolytic bacteria were obtained, at three and six hours after starting fermentation with respect to that obtained with star grass. The three collections doubled the population of proteolytic bacteria three hours after starting fermentation, while at six hours only mv-12 produced effects in this bacterial group. The methane values were 37.4, 32.6, 33.2 and 32.33 g/kg of digested organic matter for the control, and the treatments mv-12, mv-14 and mv-17, respectively. Although they did not differ between plant materials, mv-12, mv-14 and mv-17 produced less methane than the star grass treatment only (P = 0.0477). It is concluded that the treatments mv-12, mv-14 and mv-17 caused modifications in the ruminal ecosystem, by increasing the population of total cellulolytic organisms and proteolytic bacteria; in addition to reducing the protozoan population. The methane estimated from crude protein concentration also decreased. [ABSTRACT FROM AUTHOR]

The effect of the inclusion of four levels of VITAFERT (0; 4.5, 6.0, 8.0 %) on the nutritive value of T. diversifolia and P. purpureum (cv. Cuba CT-169) mixed silages mixed in two proportions (40:60 and 60:40 wet basis). The chemical composition of silages improved, in terms of higher crude protein and lower neutral detergent fiber, when including VITAFERT at 4.5 and 6.0 %.The analysis of in vitro gas production showed that there was interaction between the three factors in the initial and intermediate phases of the fermentation (P < 0.05). In the intermediate phase, the highest gas production at all times corresponded to 60 % T. diversifolia and 8.0 % of VITAFERT (P < 0.05). In the final phase, there was no interaction between the three factors and the individual interactions indicated that the highest gas production was obtained by ensiling 60% T. diversifolia with 8.0% VITAFERT (P < 0.001). Regarding the kinetic parameters, the treatment with 60 % of T. diversifolia and 8.0 % of VITAFERT had the highest gas production potential (94.69 ml.g-1 OMinc) and Vmax (2.58 ml.g-1 OMinch-1), although it reached Vmax later (7.46 h). It is concluded that the use of 4.5 and 6.0% of VITAFERT as a mixed silages additive of T. diversifolia and P. purpureum (v. CUBA CT-169) improved the chemical composition of silage. Likewise, the best indicators of the in vitro fermentation of mixed silages were obtained with 60 % of T. diversifolia and 8.0 % of VITAFERT. [ABSTRACT FROM AUTHOR]