Effects of Sesbania sesban and Carduus pycnocephalus leaves and Fenugreek (Trigonella foenum-graecum L.) seeds and their extracts on partitioning of nutrients from roughage- and concentrate-based feeds to methane

The leaves of Carduus and Sesbania and seeds of Fenugreek and their extracts in water, methanol/water (1:1 and 0.95:0.05, v/v) were evaluated for their effects on methane production and partitioning of nutrients in hay or concentrate-hay (68:32)-based diets. When incubated alone, all the three test plants had higher (P<0.05) partitioning factor (PF), expressed as mg truly degraded substrate/ml gas produced (from 3.35 to 4.86) compared to the basal substrate hay (PF = 3.11) or concentrate-hay mixture (PF = 3.16), indicating increased efficiency of microbial mass production. The lowest net methane production of 0.120 ml/ml of net gas and 0.0283 ml/mg on truly degraded substrate basis was obtained for Carduus when rumen liquor was taken from hay fed animal; and when rumen liquor was taken from concentrate fed animal these values for Carduus were 0.116 ml/ml of net gas and 0.0253 ml/mg truly degraded substrate. These values were lower when compared for hay or concentrate-hay mixture as a substrate (0.176–0.185 ml/ml of net gas and 0.0565–0.0587 ml/mg truly degraded substrate) (P<0.05). These values for Fenugreek and Sesbania were intermediate between those for hay and Carduus. On supplementation to the basal diets, Carduus reduced methane level by 20–21.5% on substrate-degraded basis (P<0.05) for both the basal diets. Saponin rich Fenugreek and Sesbania did not show any methane inhibition on volume basis despite decrease in the protozoal numbers by nearly 50% in both the basal diets. On the other hand, supplementation of Fenugreek and Sesbania to hay or concentrate-hay mixture increased the PF and decreased methane production per unit substrate degraded, suggesting that these supplements enhanced the efficiency of rumen fermentation. The methanol/water (1:1, v/v) extract of Carduus reduced methane level by 7.6–7.8% (P<0.05) while no reduction was observed for Fenugreek and Sesbania extracts. No change in methane levels on addition of a tannin inactivating agent, polyethylene glycol (MW 6000) or of saponin rich fraction from Carduus leaves to the in vitro incubations containing Carduus leaves together with very low saponin content in these leaves showed that the active moiety(ies) in Carduus is non-tannin and non-saponin. The efficacy of the supplements studied in this study in vitro should be investigated in vivo. The supplementation of Carduus leaves could be effective for both roughage and concentrate fed animals; whereas, Fenugreek seeds and Sesbania leaves are expected to be more effective for concentrate fed animals.