Effects of Energy Source Addition on In vitro Digestioi Kinetics of Corn Stover Fiber

Abstract

Harvatine, D.I., Cherney, D.J.R. and Cherney, J.H. 1998. Effects of energy source addition on in vitro digestion kinetics of corn stover fiber. J. Appl. Anim. Res., 13: 105–117.

The effects of energy source addition on in vitro corn stover (Zea mays L.) neutral detergent fiber (NDF) digestibility were evaluated using eight corn stover populations varying in quality (66.76 to 74.33% NDF) and addition of glucose (25 or 50 mM) or ear corn (25 or 50%) during 48h digestion. Stover samples were supplemented with ear corn (35.5% NDF) as a fraction of initial corn stover sample weight (0–50% ear corn addition). Increasing levels of energy addition decreased the NDF digestibility of the stover fiber (P<0.01). Glucose, the more readily available energy source, had a greater impact on decreasing stover digestibility. When comparing six levels of corn addition (0 to 100%) using two stover populations, com addition beyond 25% significantly depressed NDF digestibility (P<0.05). Stover population affected the NDF digestibility of the sample (P<0.05). Increased corn addition resulted in decreased pH levels after 48h of digestion (P<0.01), which may account for decreased NDF digestibility. Two levels of corn addition (25 and 50% ear corn) and two stover populations were used to evaluate the effects of energy addition on fiber digestion kinetics over 96h digestion. The addition of ear corn did not significantly affect the lag time or rate of fiber digestion (P>0.05). Increasing the level of corn addition decreased the indigestible NDF residue, the potentially digestible fiber and the NDF digestibility of the sample (P<0.01). Results suggest that NDF digestibility of the whole plant may be a better evaluator of the nutritive value of com from a ruminant perspective than NDF digestibility of the stover.

Keywords:

• In vitro digestion
• fiber
• corn stover
• NDF digestibility