Resumen

VALLES DE LA MORA, Braulio; CASTILLO GALLEGOS, Epigmenio  y  BERNAL BARRAGAN, Hugo. Yield, and ruminal dry matter and energy degradability of ten tropical grasses harvested at four ages. Rev. mex. de cienc. pecuarias [online]. 2016, vol.7, n.2, pp.141-158. ISSN 2448-6698.

The objective of the study was to determine dry mater yield (DMY), and in situ ruminal degradable dry matter and energy of ten grasses of the genera Brachiaria: B. brizantha (Insurgente), B. decumbens (Señal), B. humidicola (Chetumal), B. brizantha x B. ruzieziensis (Mulato I); Panicum: P. maximum cv. Mombasa, P. maximum cv. Guinea, P. maximum cv. Tanzania; and, Pennisetum: P. purpureum cv. Taiwan, P. purpureum cv. Cuban king grass, P. purpureum cv. Purple king grass, at 3, 6, 9 and 12 wk of regrowth, in three evaluation cycles. DMY for Pennisetum, Brachiaria and Panicum was: 3,037, 1,689 and 1,872 kg ha-1 (P<0.05). CP concentration decreased from 11.6 to 6.9 % (3 to 12 wk), without differences among genera. Concentration (%) of NDF, ADF and LIG were: 72.1, 43.5 and 8.1 (Brachiaria); 73.0, 45.8 and 9.0 (Panicum); and 68.8, 44.4 and 9.1 % (Pennisetum), values were 68.1, 40.1 and 8.2 (at 3 wk); and 76.2, 49.7 and 9.5 (at 12 wk). The in situ DM degradability was: 70.0 % (Brachiaria), 65.8 % (Panicum) and 72.9 % (Pennisetum) and decreased from 71.7 to 62.9 % (from 3 to 12 wk). Gross energy (GE) pre-incubation, was 3,802, 3,756, and 3,608 kcal kg-1 DM, for Brachiaria, Panicum, and Pennisetum, with no changes due to age of regrowth. In situ ruminal energy degradability (as % of incubated GE) was: 55.6, 51.4, and 57.9 % for Brachiaria, Panicum; and Pennisetum. In conclusion, age of regrowth and genus affected the nutritive value of the evaluated grasses.

Palabras llave : Tropical grasses; Regrowth age; Ruminal degradability; Dry matter.