Influence of the composition and diversity of tree fodder grazed on the selection and voluntary intake by cattle in a tropical forest

The objective of this study was to evaluate the influence of the composition and diversity of plant species browsed in a tropical dry forest, on the selection and voluntary intake (VI) by cattle during two seasons of the year. Plant species selection and VI of nine adult cattle (390 ± 13 kg of live weight) was evaluated for 7 weeks during the dry and rainy seasons on secondary vegetation (acahual). The composition, structure, diversity and importance value index were measured for fodder species browsed by cattle. The bite frequency (BF), preference index (PI) and VI of plants were also recorded. A total of 4882 plants belonging to 26 species and 17 families were registered, with a Shannon–Wiener diversity (H′) of 2.45. The species with the highest BF, PI and VI (P < 0.05) were Gymnopodium floribundum, Neomillspaughia emarginata, Mimosa bahamensis, Diospyros anisandra and Randia obcordata. The VI was higher (P < 0.05) in the rainy season than in the dry season (12.48 and 10.26 kg of DM/animal/day, respectively) and corresponded with a higher intake (P < 0.05) of nutrients and secondary metabolites. The density of species in the acahual played a determinant role in the VI of cattle, and the secondary metabolite content of plants did not interfere with the VI. We concluded, that the acahual vegetation provides sufficient forage for ruminant given its high plant diversity, guaranteeing the VI and adequate provision of nutrients for cattle.