In sacco dry matter degradation of whole and corn plant fractions

Whole corn plant without ear (WCP) and corn without ear, fractionized into upper third portion (UTP), middle third portion (MTP) and lower third portion (LTP) were evaluated for ruminal dry matter (DM) degradation kinetics. The different samples were collected during dough stage. The animals used for this in sacco experiment were indigenous fistulated sheep, fed (ad libitum) with napier grass. A concentrate mixture and mineralized salt were also provided daily to the animals. During the incubation period, nylon bags containing forage samples (3g) were placed into rumen of each animal. They were incubated twice in the rumen for 0, 6, 12, 24, 48 and 72 h. After incubation, kinetics of degradation were adjusted to an exponential model: D(t) = a+b (1-e raised to negative ct), where D(t) is the percentage DM disappearance in the bag for time t, of the rapidly (a) and slowly (b) degradable components and c is the constant rate of degradation for the second component expressed in percent/h. Effective degradation (ED, percent) of DM was calculated according to the formula: ED = a+bc/(c+k), where k 0.02/h. The nutrient composition of corn and its fractions were significantly different from each other. Ash was highest in WCP. Crude protein (CP) was highest in UTP folowed by WCP and the lowest was observed in LTP. Cell wall (neutral detergent fiber, NDF) was highest in UTP and ligno-celulose (acid detergent fiber, ADF) was highest in MTP. Acid detergent lignin (ADL) was highest in LTP. There was a significant variation on in sacco DM disappearance against incubation time. LTP was observe to have the highest percent DM disappearance across time. Degradation kinetics differed significantly across botanical fractions. LTP had the highest fraction followed by MTP and lowest in WCP and UTP. The b and a+b fractions were highest in WCP followed by UTP and lowest in MTP and LTP. The rate of degradation of b fraction (c) was highest in MTP (0.0412/h) and lowest in WCP (0.0255/h). The ED was highest in LTP (50.32 percent) followed by WCP (47.16 percent), MTP (40.02 percent) and UTP (45.34 percent). This study showed variation on degradability kinetics of corn plant and its botanical fractions