Nutritional characteristics of a naturalized narrowleaf trefoil (Lotus tenuis Wald et Kit) pasture. I. Effect of season, cutting frequency and residue'|s height

Claudia Wernli K.1; Delia Echeverría D.2 y Fernando Casio G.3

The study was done in thé Aconcagua Valley, under irrigation, using a randomized block design, with a 3 x 4 x 2 factorial arrangement, namely: three seasons (spring, summer and autumn), four cutting frequencies (every 21; 28; 53 and 42 days). and two residual heights (2 and 6 cm), with three replicates. The pasture showed high quality as forage resource, with values for crude protein (CP), in vitro dry or organic matter digestibility (IVDMD or IVOMDl. cell wall contents (CWC) and acid detergent fiber (ADF) that ranged (overall factors studied) between 20 and 24%, 72 and 77%, 28 and 36%, and 24 and 32%, on a DM basis, respectively. In spring and summer, a decrease in cutting frequency produced a decline in IVDMD and IVOMD, which was associated with a decline in CP and an increase in CWC. None of these parameters varied in autumn, with exception of IVOMD, that increased when cutting frequency decreased. When residual height was increased in spring, the IVOMD and CP decreased, but the ADF content increased. In autumn, however, the opposite was found, and in summer these parameters did not change according to residual height. The contrast found between autumn and the other two seasons, could be partly explained by the higher proportion of regrowth of the trefoil plants during autumn. The ash, Ca, and P content declined significantly with the decrease in cutting frequency. The fiber components (ADF, cellulose and lignin) did not change in autumn with the decrease in cutting frequency, with both residue heights. This was also found in spring, with the 2 cm residue. However, in spring, with the 6 cm and in summer with both residues, a decrease in cutting frequency originated an increment in fiber level, which varied according to the season and residual height.

1 Estación Experimental La Platina (INIA), CasiIla 439, Correo 3, Santiago, Chile.
2 Esmeralda 90, Los Andes, Chile.
3 Universidad Católica de Valparaiso, CasiIla 4, Quillota, Chile.