Evaluation and use of glycerol in the nutrition of pigs, poultry and ruminants | Bewertung und Einsatzmöglichkeiten von Glycerin in der Schweine-, Geflügel- und Wiederkäuerfütterung
2007
Steingass, H., Hohenheim Univ. (Deutschland). Institut für Tierernährung
The role of Glycerol as feedstuff has gained significance in the last few years due to the vast increase in 'biodiesel' production, where glycerol is a by product of this process. Digestibility of glycerol in pigs and poultry is very high, but intermediary utilization is limited. Feeding glycerol in shares higher than 5% leads to an increased excretion via urine and hence decreases metabolizability of energy. At an inclusion rate of about 5% of DM, ME content for pigs and poultry is about 17,5 MJ ME/kg pure glycerol. Feed intake is enhanced up to levels of 15% in DM, but due to decreased metabolizability of energy growth performance is not concomitantly increasing. For pigs and poultry it is of advantage to use glycerol up to 5% in the diet, higher shares are not recommended, however. Content of Net-Energy-Lactation (NEL) in ruminants is about 9MJ/kg pure glycerol. Exact results from metabolism studies are (yet) lacking, however. Glycerol is fermented in the rumen to a varying extent. The main end product of fermentation is propionic acid, although production of reasonable quantities of acetic- and butyric acid is also reported. Inclusion levels up to 5% in total DM tend to increase feed intake and milk production with no distinct effect on milk composition. Due to its glucogenic potential, it is theoretically evident that glycerol may help to prevent ketosis. The experimental results are inconsistent, however. To find a final opinion, further investigations are necessary.
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