254 Pastos y Forrajes, Vol. 41, No. 4, October-December, 254-260, 2018 / Juana L. Galindo-Blanco Scientifc Paper Silvopastoral system with Tithonia diversifolia (Hemsl.) A. Gray: effect on the rumen microbial population of cows Juana L. Galindo-Blanco, Idalmis Rodríguez-García, Niurca González-Ibarra, Roberto García- López and Magaly Herrera-Villafranca Instituto de Ciencia Animal, Apartado Postal 24, San José de las Lajas, Mayabeque, Cuba E-mail: jgalindo@ica.co.cu Abstract A trial was conducted in order to evaluate the effect of a silvopastoral system with Tithonia diversifolia (Hemsl. ) A Gray, associated with a mixture of tropical grasses, on the rumen microbial population of dairy cows under production conditions. One hundred Holstein cows were used, which grazed in a leader-follower system, with permanence time of two days. The grazing in T. diversifolia occurred at night, and the animals remained from 5:00 p.m. until 5:00 a.m. For the rumen liquid collection six cows were randomly selected in each of the sampling times. The populations of total viable, amylolytic and cellulolytic bacteria were more numerous when the cows grazed on the SPS with T. diversifolia, with regards to grass grazing. The methanogen values were 9,83 and 19,33 10 10 CFU mL -1 , and the protozoa values, of 4,67 and 7,67 10 5 cells mL -1 for SPS with T. diversifolia and grasses, respectively. The pH and NH 3 were higher in the SPS. The microbial biomass showed values of 196,9 and 192,3 g, and the organic matter that was fermented, of 547,2 and 506,4 g for SPS and grasses, respectively. It is concluded that the silvopastoral system with T. diversifolia improved the rumen ecosystem, by increasing the organisms that degrade fber and reducing protozoa and methanogens; as well as making a higher quantity of fermented organic matter for the synthesis of microbial protein available for the animal. Keywords: grazing, methanogenic bacterium, protozoa, rumen Introduction At present efforts are made aimed at diversify- ing the forage offer in traditional animal husbandry systems and the implementation of silvopastoral systems is promoted, among which Tithonia di- versifolia ( Hemsl.) A. Gray (Gallego-Castro et al., 2017a) particularly stands out, which can constitute a good alternative in cattle feeding. Among its nutritional characteristics the pro- tein content, soluble carbohydrates and tannin con- tent stand out, important indicators which should be analyzed, because these components can help improve the feeding balance regarding the energy and protein contribution in the diet of dairy cattle (Gallego-Castro et al., 2017b; Mahecha-Ledesma and Angulo-Arizala, 2017). In turn, the protein contribution can contribute to improve the rumen balance and increase the effciency for the transformation of ammonia into microbial protein, which would imply lower ener- gy costs due to losses of rumen ammonia, methane and CO 2 , which decrease the possible environmen- tal contamination. Regarding secondary metabolites, Galindo et al. (2017) reported that the presence of total phenols, tannins, saponins, among other compounds, is variable in the plant. Likewise, Hess (2006) stated that tannins are associated with the reduction in methane production; this coincides with the report by Galindo et al. (2012), who found that the inclusion of 10 and 20 % of T. diversifolia caused reductions in the population of rumen methanogens. Gallego-Castro (2016) proved that a silvopas- toral system (SPS) of T. diversifolia associated with kikuyu grass increased milk production, as well as milk quality. In this sense, García-López et al. (2016) also found increases in production when they used a SPS with this species. The nutritional characteristics of T. diversifo- lia exert an important effect on the productive yield of the animals; however, the studies related to its infuence on rumen ecology have been conducted under in vitro and in situ conditions, and there are no reports of its effect under production conditions. Hence the objective of this study was to evaluate the effect of a silvopastoral system with T. diversi- folia, associated with a mixture of tropical grasses, on the rumen microbial population in dairy cows under production conditions.