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The effects of urea-treated cornsilage and barley straw tre,_ted with 5%
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of urea solution on fattening performance of Holstein male calve was studied
in a randomised complete block design, using 24 male calves of siX month age,
with a mean live weight of 03.5:t64.14 Kg. Six total mixed _rations, (1)
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concentrate 50%, alfalfa hay 35% and untreated corn1rlage 15%, (2)
concentrate 50% and alfalfa hay 50%, (3) concentJate 50%, and untreated-cornsilage 50%, (4) concentrate 50% and treated _orn silage 50% ,
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(5) concentrate 50% and treated barley straw 50%, and (6) concentrate 85% and alfalfa hay 15% were fed to the calves for a 120 day period. The rations were fed individually, live weight and feed consumtion being measured every
two weeks. Apparent digestibilty of the rations (using Cr203) and blood urea space were determined. At the end of the experiment the calves were slaughtered, their dressing percentages and carcass cuts measured. The results indicated that: average daily gain, feed intake and feed conversion in calves fed with ration 6 were higher than those in calves fed with the other rations.
The difference between digestion coefficient of ration six with that in others was significant (P<0.05). Carcass cuts, loin area and chanal fat of the calves
which were fed with ration 5 were superior in comparIson with those in calves fed with to the other rations(P<0.O5). According to obtained data, we can use urea space method to evaluate the body composition of fattening bull calves.
The fattening performance of the calves inai(;ated that ration 6 was superior to others.