Abstract

RAMIREZ, John; POSADA O, Sandra  and  NOGUERA, Ricardo. Effects of Kikuyu grass (Pennisetum clandestinum) age and different forage: concentrate ratios on methanogenesis. Rev.MVZ Cordoba [online]. 2015, vol.20, n.3, pp.4726-4738. ISSN 0122-0268.

Objective. To evaluate the effect of Kikuyu grass (Pennisetum clandestinum) harvested at two different ages and three forage: concentrate supplement ratios (F/C) on methane (CH₄) production, dry matter digestibility (DMD), and fermentation profile using the in vitro gas production technique. Materials and methods. six treatments, resulting from the combination of pasture age (30 or 60 days) and F/C (100/0, 75/25, or 50/50) were evaluated using a 2x3 factorial design. The response variables were measured 6, 12, 24 and 48 hours after incubation. A repeated-measure over time design was used to analyze the data, and differences between means were determined with the LSMEANS procedure of SAS. Results. the youngest grass (30 days) was more digestible, produced less CH₄ per gram of digestible dry matter (_dDM) and more total volatile fatty acids (VFA) compared to the oldest grass (60 days; p <0.05). Reductions of the F/C ratio increased DMD and CH₄ production per gram of _dDM (p<0.05) but had no significant effect on VFA concentration (p>0.05). Conclusions. under in vitro conditions and pH close to neutrality, the older grass reduces DMD and increases CH₄ production per gram of _dDM, while a F/C reduction increases DMD and CH₄ production per gram of _dDM, which differs with reports conducted in vivo.

Keywords : Carbohydrates; in vitro digestibility; grass maturity; methane production.

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