Effects of local energy sources on the in situ digestibility and ruminal kinetic of erythrina poeppigiana foliage in a silvopastoral system

This study evaluated the effect of sorghum grain (Sg), green banana (Gb), polished rice (Pr), and sugarcane molasses (M o ) on the "in situ" digestibility ruminal kinetic of Poró ( Erythrina poeppigiana ) foliage under silvopastoral conditions in Turrialba, Costa Rica.Fou r ruminally cannulated Romosinuano steers with a mean live weight of 450 kg (SD 31 ) were used. The experiment was designed as a 4 x 4 Latin Square with one square and four periods . Steers grazed in twelve paddocks on pasture composed of African star - grass ( Cynodon niemfuensis ), ruzzy grass ( Brachiaria rusisiensis) , and natural grasses ( Axonopus compresus and Paspalum conjugatum ), under a rotational grazing system. Energy sources were supplemented at 0.60 Mcal ME /100 kg (BW) / day. The stee r were supplemented daily with fresh foliage (leaves, petioles, and stems) of Poró at 0.5 kg of DM/100 kg BW. Significant differences (P< 0.05) were found among the DM of energetic supplements for initial degradability , potential degradability and degradation rate . The effects of treatments on the degradability parameters of the DM of Erythrina and the grass blend as well as on N - NH 3 and pH content , were not significant (P < 0.05). In addition, t here were no significant differences (P< 0.05) among treatments for total concentration of volatile fatty acids ( VFA ́s ) (mmol) : (Pr = 87.0, G b = 95.0, Sg =96.0, Mo = 87.0); however, the proportion of a ce tic a cid, propionic acid and butyric acid presented significant differences (P > 0.05) due to the effect of the molasses. The fermentation pattern was typical of cattlegrazing diets under tropical conditions, with the molar proportion of acetic acid greater than 65%, between 13 and 16% for propionic acid and between 9 and 12% for butyric acid.