Effect of cassava foliage from “sweet” and “bitter” varieties on methane production in an in vitro incubation of molasses supplemented with potassium nitrate or urea

Le Thuy Binh Phuong, T R Preston* and R A Leng**

Nong Lam University, Viet Nam
binhphuongty27@yahoo.com
* Finca Ecologica, TOSOLY, UTA (Colombia)
AA#48, Socorro, Santander, Colombia
** University of New England, Armidale NSW, Australia

Abstract

In this study, two issues were investigated: effect of varieties and processing of cassava foliage on protein solubility;  the impact of cassava foliage and nitrate on the enhancing  of  methane reduction from in vitro rumen fermentation.

Experiment 1 was designed as a 3*2 factorial with 6 treatments and 2 repetitions. The sun-dried processing of cassava foliage reduced nitrogen solubility and HCN concentration. The bitter variety gave higher HCN concentration but lower nitrogen solubility than the sweet variety.

Experiment  2 was designed as a 3*2*2 factorial arrangement in a randomized block design the factors being: cassava foliage varieties (sweet, bitter 1 and bitter 2), form of cassava foliage (fresh and sun-dried) and NPN (urea and potassium nitrate). Representative samples (12g DM) was added 960ml of buffer solution and 240ml of cattle rumen fluid for 24h in vitro incubation.

Gas production was higher in urea treatment  than in nitrate treatment but there was no difference among varieties and processing of cassava foliage. Bitter cassava foliage  resulted in reducing methane production per unit substrate solubilized compared with sweet variety:  fresh foliage supported lower methane  than sun-dried cassava foliage. The replacing of urea by nitrate as NPN also  reduced methane production.

Key word: HCN, nitrate, nitrogen solubility, rumen fermentation