Influence of Cassia fistula leaf powder on in vitro ruminal fermentation, gas production and degradability of diets for ruminants

Medicinal plants with high phytochemical values are critical for enhancing the productivity of livestock systems, while reducing their environmental impact. This study investigated the influence of graded levels of Cassia fistula leaf powder (CFLP) on in vitro ruminal fermentation parameters, gas production and degradability of diets for ruminants. Five concentrate diets were formulated to contain varying levels of CFLP (0, 15, 30, 45 and 60 mg/g dry matter (DM), denoted CF0, CF15, CF30, CF45 and CF60, respectively). The concentrate diets combined with guinea grass hay at the ratio of 4 : 6 (concentrate : forage) served as a substrate for the study. In vitro gas production test was performed by incubating 200 mg DM of the substrate for 48 h. At the end of the incubation period, the total gas and methane production, nutrient digestibility, in vitro fermentation and post-incubation parameters were evaluated. Results revealed a linear decrease ( P < 0.001) in gas and methane production across the treatment groups with an increase in CFLP levels. The amount of methane produced varied from 9.3 ml/200 mg DM in the CF60 diet to 20 ml/200 mg DM in the control diet. Nutrient digestibility was highest in the control diet and lowest in the CF60 diet. There was a linear decrease in ammonia-nitrogen and total volatile fatty acid (TVFA) concentration with an increase in the CFLP level. Inclusion of CFLP up to 30 mg/g DM ruminant diet was found to reduce methane production and ammonia-nitrogen concentration with minimal effects on nutrient degradation and TVFA concentration.