predicting 'of Max'imumForage hltake"Capacity in Cattle from • ~ _ \ ~: •.J • ; _: Degradability Characteristics, Passage ·Rate.and Rumen Pool Size of NDF '.

An experiment (5 x 5 Latin Square) was conducted to estimate the physical fill of tropical forages and maximum intake capacity of five mature non-pregnant crossbred dairy heifers kept under zero grazing system. Five (5) forages [Brachiaria brizantha hay (BH), Maize (Zea mays) silage (MS), Lucerne (Medicago sativa) hay (LH), Lucerne and grass hay (LGH) and urea-treated rice straw (UTRS)) were used. The forages were fed as sale diets ad libitum with only minerals and vitamins supplements. Water was provided all the time and measured daily. Voluntary feed intake (VFJ) and faecal olflput were measured for seven days. Degradability characteristics were obtained in situ using the ' nylon bag technique. Rumen pool size of NDF was measured by rumen evacuation technique. Passage rates were calculated based on faecal output and rumen pool size of NDF. There was a marked difference (P<O.OOOl) between the rate and extent at which NDF for tropical forages was degraded. The rate of passage ( % h · i) was different (P<0.03) between forage diets with values rangingfrom 1.4 to 1.8for MS and UTRS, respectively. Rumen pool sizes of NDF were different (P<O.Ol) between forage diets and weighed 4.8, 3.8, 4.7, 5.2 and 4.5 kg for BH, MS, LH, LGHand UTRS, respectively. Fill (days) also varied between forage diets and ranged from- 1.4 for UTRS to 1.8 for MS. The intake capacity o