Effect of the re-growth age on the nutritive quality of Neonotonia wightii in the Cauto valley, Cuba

Resumen

Through a completely randomized design with six replicates, the effect of the re-growth age (30, 45, 60, 75 and 90 d) on the nutritive quality of Neonotonia wightii was assessed, as well as the relation between its digestibility, ME and tannins. The experiment was conducted during the trimesters January-February-March (dry season) and May-June-July (rainy season), on a brown soil with carbonate, without irrigation or fertilization. The DM, silica (Si), NDF, ADF and lignin increased (P < 0.05) with age and the highest values were obtained at 180 d, while the CP, DM in vitro digestibility and ME diminished (P < 0.05). The highest values were reached at 30 d. The total phenols, total tannins and total condensed tannins increased (P < 0.05) with the re-growth age in both seasons and reached the maximum concentrations at 90 d (10.7, 5.24 and 77.66 g/kg DM in May-June-July and 8.24, 3.12 and 96.64 g/kg DM in January-February-March, respectively). In both seasons, high negative correlations (between -0.82 and -0.99) were obtained between the total phenols, total tannins and total condensed tannins and the DM in vitro digestibility, OMD, DM in situ digestibility, true digestibility (TD) and ME. It is concluded that age had a marked effect on the indicators assessed, more highlighted in the rainy season, when the nutritive quality diminished due to the increase of the fiber fraction, diminishing of the protein, digestibility and ME, and due to the inverse relation between the two last indicators and the phenolic compounds. Studies on other legumes under different edafoclimatic and management conditions are suggested.
Key words: legume, phenolic compound, tannins, digestibility, energy.