PSX-18 Inclusion of physically effective fiber from forage on whole corn based diets for beef cattle and its effects on the intake and digestibilities of dry matter starch and neutral detergent fiber.

摘要

Bos indicus cattle are susceptible to metabolic disorders associated to the use of diets without roughage. Therefore, our objective was to obtain the physically effective fiber content from forage (pefNDF) necessary to improve the intake and digestibility of dry matter (DM), potentially degraded NDF (pdNDF) and starch. Five Nellore bulls rumen cannulated (BW = 393 ± 9 kg) were used in a 5 x 5 Latin square design. The treatments were:1) whole grain (850 g/kg) plus pelleted concentrate, and no forage inclusion (control); and 2 to 5) inclusion of 50, 150, 250 and 350 g/kg of sugarcane, respectively, and no inclusion of pelleted concentrate. A Pen State Particle Separator was used to determine the dietary pefNDF. Ruminal digestibilities were estimated through omasal flux using double marker system. Total digestibilities were estimated by fecal spot collection (using iNDF as a marker). Ruminal pH was measured each 9-h in three consecutive days. The digestion (kd) and passage (kp) rates of pdNDF were obtained from ruminal emptying during two sampling days (one before and other after the feeding). The pefNDF inclusion was evaluated for the linear, quadratic and cubic effects, and were compared with the control using the Dunnett test (α=0.05).The measured pefNDF in the treatments 2 to 5 were, respectively, 20.5, 61.4, 102.4 and 143.3 g/kg DM. Intake and digestibilities of DM and starch were linearly decreased (P Intake and digestibilities of pdNDF were linearly increased) P20.5 g of pefNDF/kg DM maximized kd and kp of pdNDF (P2= 0.82). From our results, it is recommended to use 20.5 g/kg pefNDF from sugarcane on whole corn grain diets.