Energetic Evaluation of Glycerol in Ruminants (Energetische Bewertung von Glycerin beim Wiederkäuer)
- Publikations-Art
- Kongressbeitrag
- Autoren
- Eckl E., Steingaß H. and Drochner W.
- Erscheinungsjahr
- 2008
- Veröffentlicht in
- Berichte der Gesellschaft für Ernährungsphysiologie
- Herausgeber
- Gesellschaft für Ernährungsphysiologie
- Verlag
- DLG-Verlags-GmbH , Frankfurt/M.
- Band/Volume
- 17/
- Serie/Bezeichnung
- Proc. Soc. Nutr. Physiol.
- ISBN / ISSN / eISSN
- 978-3-7690-4101-9
- Seite (von - bis)
- 126
- Tagungsort
- Göttingen
- Tagungsdatum
- 01.04.2008
- Schlagworte
- Glykobiologie, Wiederkäuer
The role of glycerol (GLC) as feedstuff has gained importance in the last decade due to the vast increase of biodiesel production, where GLC is accumulated as a by product. Energy content of GLC for monogastric animals is well established. In contrary, energetic evaluation for ruminants did not go beyond digestibility trials (1). This method may be insufficient, however, as the equation for calculating ME from digestible nutrients has fixed factors that were derived from mixed rations and hence may be inappropriate for GLC.Methods: GLC (pharmaceutical grade; 13.4% H2O) was added to a basal diet consisting of 370 g DM hay and 520 g DM concentrate (22% soybean meal, 36% wheat, 36% barley, 6% mineral premix on DM basis) in 5 steps (0, 37, 74, 151, 228 g DM). Each ration was tested with 4 male merino landrace lambs (BW 36±3kg). After a preliminary period of 11 days total faeces and urine was collected for a period of 7 days. In a 2 x 24h respiration period, CO2 and CH4 production and O2 consumption were measured in open circuit respiration chambers. Partitioning of ME was calculated from heat production (2) and N retention. Specific energy values of glycerol were calculated from the slopes of linear regressions relating total daily DE/ME intake (y) to GE intake (x) and NE intake to ME intake, respectively (for example see fig. 1).Results: All rations including the highest GLC contents were accepted without refusals. Stepwise addition of GLC resulted in linear responses of digestibility and energy variables (fig. 1). Specific GE digestibility of GLC was 85±4%. This was due to a negative impact of GLC on fibre digestion of the basal diet (-7±1g digestible XF/100g additional GLC). On the other hand, GLC reduced urine energy loss by 2 kJ/100 kJ additional GLC. Methane output was not affected by GLC addition. Hence metabolizability of GE (q) of GLC was 87±4%. Specific utilization of ME of GLC (kg) was 0.68±0.04. In Table 1 energy values for GLC are summarized.Conclusion: ME content of GLC in the present study was 15.6 MJ/kg DM, whereas only 13.7 MJ/kg DM are calculated with the equation of (3) using digestible nutrients. It can be concluded, that ME content of GLC calculated from digestibility leads to a considerable underestimation of energy values. This should be taken into account when monitoring energy content of feedstuffs containing GLC with routine methods based on digestibility.