Effects of energy source addition on in vitro digestion kinetics of corn stover fiber.

摘要

The effects of energy source addition on in vitro maize stover (Zea mays) NDF digestibility were evaluated using 8 maize stover populations varying in quality (66.76 to 74.33% NDF), and addition of glucose (25 or 50 mM) or ear maize (25 or 50%) during a 48-h digestion study. Stover samples were supplemented with ear maize (35.5% NDF) as a fraction of initial maize stover sample weight (0 to 50% ear maize addition). Increasing energy decreased the NDF digestibility of the stover fibre (P<0.01). Glucose had a greater impact on decreasing stover digestibility. When comparing 6 levels of maize addition (0 to 100%) using 2 stover populations, maize addition beyond 25% decreased NDF digestibility (P<0.05) and stover population affected the NDF digestibility of the sample (P<0.05). Increased maize addition resulted in decreased pH levels after 48 h digestion (P<0.01), which may account for decreased NDF digestibility. Two levels of maize addition (25 and 50% ear maize) and 2 stover populations were usedto evaluate the effects of energy addition on fibre digestion kinetics over a 96-h digestion. The addition of ear maize did not affect the lag time or rate of fibre digestion. Increasing maize addition decreased indigestible NDF residue, the potentiallydigestible fibre and the NDF digestibility of the sample (P<0.01). It is concluded that NDF digestibility of the whole plant better indicates the nutritive value of maize from a ruminant perspective than NDF digestibility of the stover.