Resumen:
This study was conducted to investigate effects of increasing doses: 0 (control), 6 (low), 12
(medium) and 24 (high) mg/g DM of ZADO® enzyme preparation mixture (ENZ) on in vitro
gas production (GP) and some ruminal fermentation parameters of the fibrous feeds Saccharum
officinarum (leaves), Andropogon gayanus (leaves), Pennisetum purpureum (leaves)
and Sorghum vulgare (straw). Rumen liquor was obtained from two Brown Swiss cows fitted
with permanent rumen cannulae fed a total mixed ration of a 500:500 commercial concentrate
and alfalfa hay ad libitum. The GP was recorded at 2, 4, 6, 8, 10, 12, 24, 48, 72 and
96 h of incubation. After 96 h, the incubation was stopped and the pH of the mixture was
determined and filtrate used to determine dry matter degradability (DMD), partitioning
factor (PF96), gas yield (GY24), in vitro organic matter digestibility (OMD), metabolizable
energy (ME), short chain fatty acids (SCFA), and microbial crude protien production (MCP).
In general, the crude protein (CP) content of the fibrous feeds was low and ranged from
23 g/kg DM (S. officinarum) to 44 (A. gayanus). The fibre contents (i.e., NDFom and ADFom)
were highest (P<0.05) in S. officinarum. Increasing ENZ dose linearly increased (P<0.05) GP of
all fibrous feeds and had a quadratically increased (P<0.05) asymptotic gas production in P.
purpureum and S. vulgare and rate of gas production in S. officinarum and S. vulgare. Addition
of ENZ also quadratically increased (P<0.05) GP at all incubation times in S. officinarum and
S. vulgare, and A. gayanus, but only at 72 h in A. gayanus. The parameters of ruminal fermentation
of OMD, ME, GY24 and SCFA linearly increased (P<0.05) and MCP linearly decreased
(P<0.05) with the ENZ addition. Addition of enzyme affected ruminal fermentation of our
feeds differently, mainly dependent on their fibre content, although dosage of enzyme was
also important as impacts generally increased at higher dosages of ENZ.
