Objective

To evaluate the effect of harvest age and season on the chemical composition, with emphasis on the energy fractioning and digestibility of Tithonia diversifolia (Hemsl.) A. Gray and Sambucus nigra L, established in a silvopastoral system in the Pasto region, Nariño, Colombia.

Materials and Methods

The study was conducted at the Obonuco Research Center of AGROSAVIA, Pasto, from January to November, 2018. A randomized block design was used, with three replicas and two treatments, associated to the factor cutting age for each species (T. diversifolia, 60 and 80 days and S. nigra, 60 and 90 days). For the study of the variables two seasons were differentiated: high and low rainfall. Yield and nutritional variables were evaluated, with emphasis on the energy value (digestible energy, metabolizable energy and net lactation energy). The software R V. 3.5.1 was used for the statistical processing. Variance analysis and Tukey’s mean comparison test, for p < 0,05, were applied.

Results

The highest digestibility values (79,3 and 77,8 %), digestible energy (3,93 and 3,32 Mcal/kg DM), metabolizable energy (2,8 and 2,7 Mcal/kg DM) and net lactation energy (1,67 and 1,63 Mcal/kg DM) appeared at the age of 60 days, in the rainy season for T. diversifolia and S. nigra, respectively. With regards to the biomass production, for T. diversifolia the dry matter yield increased significantly (p < 0,05) with age, in the two seasons, and for S. nigra in the dry season.

Conclusions

The values at higher ages (80 and 90 days) were considered acceptable, which proved the potential of these forage plants to improve the nutritional quality of diets in animal husbandry systems.

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