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Two experiments were carried out, the first being done with piglets of 11 kg and the second with heavier pigs (110 kg). A total of 24 starter piglets of 11kg, and 24 finisher gilts were individually caged in cages that permitted total and separate collection of feces and urine. Animals were fed one of the four diets, basal diet (BD) or the BD with an additional 5, 10 or 20% of glycerol (3625 kcal gross energy per kg), BD composition differed between that offered to starter piglets and that offered to finisher gilts. After a 10 days adaptation period, feces and urine were collected for 5 consecutive days in order to determine energy content. Apparent metabolizable energy (ME) of the diet was calculated as the difference between feed gross energy content and the sum of energy excreted in feces and urine.
Response of apparent ME content of crude glycerol was quadratic (P < 0.01) in starter piglets, being the apparent ME content of 3601, 3239 and 2579 Kcal/kg for diets presenting 5, 10 and 20% of glycerol respectively. When not taking into account starter piglets fed 20% of glycerol, the response was lineal and the apparent ME content estimated for glycerol was of 3463 Kcal/kg. On the contrary, in growing pigs crude glycerol response was lineal, providing an apparent ME content of 3081 Kcal/kg.
Therefore, up to 10% of crude glycerol can be supplemented to weaned piglets, obtaining an apparent ME of approximately 96% of the gross energy content of crude glycerol, while in finishing pigs higher levels can be used with an approximately 85% of the gross energy content of crude glycerol.
Lammers, P., Kerr, B., Weber, T., Dozier, W., Kidd, M., Bregenhahl, K., Honeyman, M. (2007) Energy and protein metabolism and nutrition. EAAP publication No. 124, 2007, V
