Ruminal Volatile Fatty Acid Production Rates and Fibre Digestion in Cattle Fed on Urea (Ammonia) Treated Rice Straw

Ammoniation of rice straw was tried at two levels of urea (4 and 5 per cent) and 2 levels of moisture (30 and 40 per cent by weight). Twelve Karan Swiss, male, rumen fistulated calves (2-2½ yrs) were divided in three equal groups and fed rice straw either untreated (A) or 4 per cent urea + 40 per cent moisture treated and ensiled for 30 d (B) or 5 per cent urea + 30 per cent moisture treated and ensiled for 30 d (C). The concentrate mixture was provided to meet requirements. DM intake through roughage did not differ (P < 0.05) between groups but intake through concentrate mixture was significantly (P < 0.01) lower in groups B and C. The mean TVFA concentration (m mole/100 ml SRL) was 11.52 ± 0.43 (A), 14.00 ± 1.19 B and 13.56 ± 0.92 (C) (P < 0.05). In both the groups fed urea treated rice straw, the acetate declined (P < 0.01) while propionate increased (P < 0.05). TVFA production rates (moles/d) were 9.36 ± 0.37 (A), 12.01 ±0.12 (B) and 11.92 ± 0.38 (C) (P < 0.05). The digestibility co-efficient of different cell wall components were higher in groups fed urea treated rice straw.