In vitro Gas Production as a Measure of Comparative Ruminal Microbial Activity of Animals Fed Straw Based Diet Supplemented with Either Concentrate Mixture or Urea Molasses Mineral Block Licks

Sixteen rumen Fistulated male crossbred donor calves (18-24m; 180-200 kg), were divided into 4 equal groups in a randomised block design and fed wheat straw ad lib as the sole roughage alongwith either the concentrate mixture at maintenance level (Gp I) or allowed to lick the urea-molasses-mineral block licks ‘Ex’ (UMMB ‘Ex’, Gp II) or modified UMMB ‘A’ (Gp III) or ‘B” (Gp IV) for 40d. It was observed that the wheat straw intake (kg/d) was significantly (P<0.01) higher in Gps II (4.20±0.13))III (4.07±0.16) and IV (4.22±0.20) as compared to group I (3.21±0.14). However, the total DM intake (kg/100 kg body weight) was not significantly different amongst Gps I (2.41+0.02), II (2.45±0.03), III (2.43+0.06) and IV (2.44±0.02). The cumulative in vitro gas production at 14 h was not significantly different in various groups when untreated wheat straw, urea treated (4% urea w/w+40% moisture) wheat straw and concentrate mixture were used as substrates and the rumen liquor was taken from donor animals. The coefficient of gas production (ml/g substrate) during phase I and II of incubation of different substrates for various groups were similar. The results indicated that the UMMB lick supplementation could substitute concentrate mixture in the wheat straw based diet of adult ruminant animals without affecting their microbial activity in rumen.