Effect of Exogenous Fibrolytic Enzymes and Soapnut (Sapindus mukorossi) Shell Powder on in Vitro Degradability Studies in Gir Calves

Abstract

Ruminant productivity is often constrained by the low digestibility of fibrous feed resources, primarily because of limited ruminal fibrolytic activity and the high lignocellulosic content of forages. An in vitro study was conducted to evaluate the effects of different levels of exogenous fibrolytic enzymes (cellulase and xylanase; EFE) and soapnut shell powder (SSP), alone and in combination. The substrate was prepared using groundnut haulm as roughage and BIS Type-I compound cattle feed as concentrate in a 60:40 ratio. Exogenous fibrolytic enzymes (cellulase + xylanase) were used at 0, 25,000, 50,000, 1,00,000, and 2,00,000 IU/kg of concentrate, and soapnut shell powder was used at 0, 0.1, 0.2, 0.5, and 1% of concentrate. Using these levels of EFE and SSP, twenty-five combinations were prepared for in vitro studies. The substrates with different levels of EFE and SSP were incubated for 24 hours to evaluate in vitro total gas production (IVTGP), truly degradable organic matter in rumen (TDOMR), microbial biomass production (MBP), efficiency of microbial production (EMP), and partitioning factor (PF). The analysis revealed a significant (p < 0.05) effect of EFE at 50,000 IU/kg of concentrate (20.5 ± 0.50 ml/200 mg) and SSP at 0.5% of concentrate (21.0 ± 1.00 ml/200 mg), and the combination also showed a significantly (p < 0.01) higher value (22.5 ± 0.50 ml/200 mg) at the same levels. Supplementation with EFE at 50,000 IU/kg (61.15 ± 1.26) and 1,00,000 IU/kg of concentrate (60.34 ± 1.41) produced significantly (p < 0.01) higher TDOMR values. MBP was significantly (p < 0.05) higher in the group supplemented with EFE at 1,00,000 IU/kg of concentrate (24.92 ± 3.97). No significant effect of EFE and SSP supplementation was found on EMP. PF was significant (p < 0.05) in the EFE group at 1,00,000 IU/kg of concentrate (3.89 ± 0.41), SSP at 0.2% of concentrate (3.87 ± 0.49), and the combination group of EFE and SSP at 1,00,000 IU/kg concentrate and 0.2% level (5.39 ± 0.58). Therefore, incorporation of EFE and SSP, alone and in combination, at 50,000 IU/kg and 0.5% of concentrate increased in vitro total gas production and substrate degradability. TDOMR was greatest at 50,000 IU/kg and 1,00,000 IU/kg of concentrate, while 1,00,000 IU/kg of concentrate increased microbial biomass production. Based on gas production and organic matter degradability, these levels were selected for further in vivo studies in Gir calves.