Comparative in vitro evaluation of five Commelina forage species on ruminal fermentation and methanogenesis

Abstract

In vitro gas measurement study was known to be a helpful tool for investigating the nutritional quality of feed for ruminant animals. This research was conducted to explore the ruminal fermentation and methane emission potential, and their variability pattern with changing seasons and altitudes for Commelina species, using in vitro test. Samples of the species were collected from different altitudes and seasons and used for the in vitro degradability study. Five species (C.africana, C. albescence, C. benghalensis, C. imberbis and C. diffusa), two altitudes (low and mid), and two seasons (wet and dry) were arranged in a 5 × 2 x 2 factorial manner in a completely randomized design, with three repeats of each treatment. In vitro gas and methane production as well as methane to total gas ratio were all meaningfully (P < 0.001) affected by season and altitude with the highest values observed in wet season and mid altitudes. At 24 h incubation, 44.76 and 37.82 ml/200 mg DM of total gas production was noted for wet and dry seasons respectively, while 39.77 and 47.38 ml/200 mg DM was recorded for low and mid altitudes respectively. Average gas production from immediately fermentable fractions (a) for wet season (4.21 ml) was reasonably (P < 0.001) higher than those for dry season (2.16 ml). Midlands (5.04 ml) had higher (P < 0.001) ‘a’ value than lowlands (2.77 ml). Both methane production and methane to total gas ratio exhibited a tangible decrease (P < 0.001) from wet season to dry season. 4.88 ml/200 mg DM and 6.52 ml/200 mg DM methane records were recorded for lowlands and midlands respectively. It appears that Commelina species contain nutrients that degrade in vitro, highlighting their potential supplement value for animals. The promising gas production potential added to its low methanogenic coefficient relative to the other species makes C. diffusa to the preferred supplement for poor-quality roughages followed by C. benghalensis and C. imberbis and the rest species being least preferred. But further nutrient analysis, minerals, secondary metabolites and the like, was required. And, in vivo trials must be conducted to strengthen the implications of this study.