Evaluation of Pulse By-Products Based Complete Diets for Rumen Degradation Kinetics and Microbial Biomass Synthesis by in vitro Gas Production Technique

The rumen degradation kinetics and efficiency of microbial biomass synthesis in vitro were determined for four diets (D-1, D-2, D-3 and D-4) prepared from pulse straws (red gram straw, 80% and black gram straw, 20%) and chunnies (Red gram and Black gram) as component of concentrate supplement in the ratio 50:50. Air equilibrated feed samples (200 ± 10 mg) were incubated and cumulative gas production was recorded at 2, 4, 6, 8, 10, 12, 16, 20, 24, 30, 36, 48, 60, 72, 84 and 96 h of incubation. The rate and extent of gas production were calculated by non-linear regression using the model Y = D (1 – e^–k*t). The microbial biomass synthesis was obtained by determining the ratio of truly digested organic matter (TDOM) and gas production at 24 h and 96 h. The k (h⁻¹) for D-1, D-2, D-3 and D-4 diets was 0.0563, 0.0613, 0.0604 and 0.0705 respectively. PF of diets determined at 24 and 96 h ranged from 2.42 to 2.99 and 3.29 to 3.50 respectively, where as the difference in PF was 9.1, 8,2, 15.7 and 30.9% in diets D-1, D-2, D-3 and D-4 respectively. The proportions of truly degraded organic matter converted into microbial biomass (EMBS) at 24 and 96 h of incubation in D-1, D-2, D-3 and D-4 diets (%) were 24 and 31.2; 24.8 and 31.7; 18.7 and 31.5; 23.5 and 35.3 respectively. Irrespective of time of incubation, the EMBS was almost similar among the diets which might be due to almost similar k and PF of the diets. Hence, it was concluded that the pulse by-products based diets with different level of k and PF can significantly (P<0.01) increase the microbial biomass synthesis.