Effect on methane production of source of carbohydrate, and processing/variety of cassava leaf supplement, in an in vitro rumen incubation

摘要

The aim of this study was to compare effect of two source of protein varieties and process of cassava foliage and two sources of carbohydrate on methane production in an in vitro incubation medium inoculated with rumen fluid and using cassava foliage, cassava pulp and molasses for subtract. The design was a 2*2*2 factorial arrangement of the treatments with 4 replications. The quantity of substrate in each fermentation bottle was 12g DM to which was added 240 ml of rumen fluid (from slaughtered cattle) and 960 ml of buffer solution. The incubations were done in a simple in vitro incubation using one-liter bottles with gas collection by water displacement and methane measured by an infra-red methane gas detector. The incubation was for 24hours with measurements of total gas production and methane percentage in the gas at intervals of 6, 12, 18 and 24hours. Methane production was lower when the substrate contained: cassava pulp rather than molasses as carbohydrate source; leaves from bitter rather than from sweet cassava variety; and cassava leaves that were in fresh form rather sun-dried. The methane percentage in the gas increased linearly with the length of the incubation.