Location: Food and Feed Safety Research
Title: Evaluation of feeding glycerol on free-fatty acid production and fermentation kinetics of mixed ruminal microbes in vitro Authors
Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 2, 2010
Publication Date: July 1, 2010
Citation: Krueger, N.A., Anderson, R.C., Tedeschi, L.O., Callaway, T.R., Edrington, T.S., Nisbet, D.J. 2010. Evaluation of feeding glycerol on free-fatty acid production and fermentation kinetics of mixed ruminal microbes in vitro. Bioresource Technology. 101:8469-8472. Interpretive Summary: Animal-derived foods containing unsaturated fatty acids are desired and are considered beneficial for good human health. The objective of the current research was to evaluate the effect of using glycerol as a potential feed ingredient for cattle as a means to decrease the amount of fat being saturated in the animal's stomach for incorporation into the animal's meat. These results provide evidence that using glycerol as a feed ingredient, up to 20% of the diet, will have no negative effects on digestion in the animal, and that inhibiting bacterial fat degradation may promote ruminal passage of total lipid, thereby providing greater proportions of beneficial unsaturated fat for incorporation into beef products.
Technical Abstract: Strategies to enrich ruminant-derived foods with unsaturated fatty acids are desired as these are considered beneficial for good human health. Ruminant-derived foods contain high proportions of saturated fats, a result of ruminal biohydrogenation, which rapidly saturates and thus limits the availability of free unsaturated fatty acids for assimilation. We conducted a study to evaluate the effects of glycerol’s inhibitory capability of ruminal free fatty acid production rates and its effects of fermentation kinetics of alfalfa hay in vitro. Results from in vitro incubations demonstrated 48% and 77% reductions in rates of free fatty acid accumulation in incubations supplemented with 2% or 20% added glycerol as compared to controls (5.06 ± 0.06 µmol FFA/ml per h). In vitro incubations with alfalfa hay demonstrate that increasing levels of glycerol did not affect NDF digestibility of the hay. Gas production and fermentation rate of the NDF fraction decreased, but with no clear relationship between levels of 0% to 20%. Additionally, increasing amounts of glycerol decreased the acetate concentration and altered propionate concentration, thus decreasing the acetate to propionate ratios. These results provide evidence that inhibiting bacterial fat degradation may promote ruminal passage of total lipid, thereby providing greater proportions of beneficial unsaturated fat for incorporation into beef products and indicate that glycerol supplementation greater than 20% may negatively affect fiber digestion and alter the VFA profile.