Third and fourth cuts of alfalfa forage were conserved as green, hay or ensiled
either untreated or treated with 0.31 9 HCHOJ100g OM or 2.8 g formic acid/100 g OM         and fed to Zaraibi buks weigh~q 50 kg on average.                          . The obtained results indicated that treated silages either with HCHO or
HCOOH contained higher values of OM, EE, NFE and NSC than those of green and
hay altalfa forms. The treated ensiled qlfalfa contained higher values of OM, CP, EE
and NSC, while it contained lower values of NFE, ash and NDF compared to the
untreated silage. Treaded alfalfa silages tended to have higher desirable
fermentation represented in low pH, butyric acid and higher lactic acid content
compared to the untreated silage. Protein solubility decreased with the reduction of
NPN and NH3 in the treated silages 11S well. Feed intake in terms of OM, TON and DOM significantly (P<0.05) improved in
the ensiled forage compared to the green and hey ones. The relative feeding value
(RFV) and both of digestible energy (DE) and metabolizable energy (ME) of ensiled
alfalfa increased than those of green and hey alfalfa. This accompanied with a
reduction in effective neutral detergent fiber (eNDF) values, specially with increased
NSC content of HCOOH-treated silages. The alfalfa silages diets contained the
highest (P<0.05) values of digestibility coefficients for all nutrients, except for EE in
green alfalfa which recorded the highest but without significant difference with
HCOOH-treated silage. Rumen liquor pH and total VFA recorded the highest (P<0.05) values with
green alfalfa diet and significantly decreased with HCOOH and HCHO-treaded diets.
The NH3-N concentration was impaired (P with alfalfa hey. All animals were in positive N-balance and percentage of N-balance
to N-intake or digested were the heights (P silages. It could be concluded the formaldehyde treatment for alfalfa silage is more
effective in reducing its NDF content and increasing its NSC content which reflected
positively on fermentation in the rumen and improving feed utilization compared to the
other tested forms of alfalfa.