Glycerol as an Energy Source for Ruminants: A Meta-Analysis of in Vitro Experiments
Abstract: Glycerol or glycerin
is generally recognized as a safe compound to be used in animal feed,
especially for ruminants. A number of in vitro studies related to glycerol
supplementation in ruminant ration have been published but to date the results
have not been summarized. The objective of this study was, therefore, to
evaluate in vitro digestibility, ruminal fermentation characteristics, total
gas and methane production through the meta-analysis approach. Meta-analysis
was applied to 13 experiments and 42 treatments dealing with glycerol
supplementation in ruminants. Data were analyzed by general linear model
procedure in which the glycerol levels and the different studies were treated
as fixed effects. Results revealed that glycerol supplementation did not affect
the in vitro digestibility and total VFA production, but significantly
decreased molar proportion of acetate and iso-valerate (P<0.05). In
contrast, molar proportion of propionate, butyrate, and valerate significantly
increased, and thus the ratio of acetate to propionate declined linearly
(P<0.05). Methane production decreased linearly and accompanied with an
increase of total gas production with increasing levels of glycerol
supplementation (P<0.05). It is concluded that the use of glycerol as an energy
substitution in animal feed has no detrimental effects in the rumen and
environmentally friendly.
Keywords: fermentation;
glycerol; in vitro; meta-analysis; ruminant
Author: T. M. Syahniar, M.
Ridla, A. A. Samsudin, A. Jayanegara
Journal Code: jppeternakangg160046
