DISCUSSION
The results of Experiment I indir::c that when wheat straw alone was fed
to animals, ruminal microbial attivity was poor, as shown by low rates of
degradation of OM and varib>us fibrous fractions. This was mainly owing to
the fact that straws are deficient in nitrogen, energy and minerals and as such,
could not support optimum microbial activity in the rumen. Owing to these
limitations, fermentation rate in the rumen of animals fed on straw diet alone
was slow. However, when concentrate mixture, UMMB lick or ingredients of
UMMB lick were supplemented to the wheat straw diet of animals, as in
Groups II, 111 and IV, respectively, the rate of lumen fermentation was enhanced
considerably, as is evident from the significant (PcO.01) increase in
the OM disappearance from the nylon bags. Nitrogen, energy and minerals
were sufficiently available to ruminal microbes with these supplements, which
obviously increased their number (Sudana and Len& 1986), leading to greater
fermentative activity in the rumen. It seems that the amount of nitrogen and
energy available to rumen microbes through concentrate mixture (at maintenance
level) and UMMB lick was sufficient as no difference in the rate of
degradation of OM and other Fibrous Fractions was observed when concentrate
mixture or UMMB lick was provided to animals along with a basal diet
of wheat straw.
Response to fermentation of straw in the rumen was also observed when N
was supplemented in the form of urea (Campling et al., 1962). However, for
the optimum utilization of supplemented N, adequate energy was also neces
sary, as it was shown that neither intake nor digestibility of untreated barley
straw (CP=6%) increased on supplementation of urea owing to inadequate
energy (Orskov and Grubb, 1978 ). Silva andorskov ( 1983) also observed a
diffe:‘::ice in the rate of fermentation of untreated wheat straw when the host
animai’s diet was different. A significantly higher rate of degradation was observed
when untreated straw was incubated in the rumen of sheep Fed on ammoniated
rather thrn untreated straw. These differences were probably owing
to an increased concentration of cellulolytic organisms, giving rise to greater