Determination of the effect of the level of corn starch in the diet on the energy value of crude glycerin in swine

Abstract Text: Crude glycerin (CG), a byproduct of biodiesel, generates interest in animal feed because of its energy value. In order to determine the effect of the level of starch in the diet on the digestible energy (DE) of crude glycerin in swine this study was developed. The DE was determined for crude glycerin with 10 barrows placed in metabolic cages using 0.5% chromium oxide as an indigestible dietary indicator. The treatments consisted in two starch levels (SL) 10 and 12%, and five levels of CG substitution 0, 2.5, 5, 7.5 and 10%. Each period consisted of 5-d adjustment period, a 2-d collection period. During the collection period, feces and urine were collected separately and stored at 0°C until analysis in order to calculate metabolized energy (ME). The data were subjected to multiple linear regression analysis determining the value of the DE and ME of CG, as the slope of the line and N metabolism data as a Latin square design using the GLM and REG modules of SAS ver. 9.2. DE value of diet corrected by dietary starch content was described as, DE of diet corrected by starch (Kcal/kg) = 2952.1 +30.9(Period) +4427.3(CG) + 31.5(SL) - 691.5(CG: SL). According to the slope, DE value of CG depended of SL (P <0.001) estimated in 4427 and 3769 Kcal/kg DM for 10 and 12% of SL, respectively. ME of CG was determined as 3436 Kcal/kg DM, no effect (P>0.05) of SL on the value of the ME of the CG was observed, although no quadratic effect of level of CG was observed (P>0.05). An increase (P <0.001) in urinary energy (UE) was observed as CG increased in the diet; UE (Kcal/kg DMI) = 159.6 +7.99(CG). There was an interaction between CG and SL (P <0.001) which caused an increased in the amount of nitrogen digestible (AND) when CG increased by the 10% SL. However, the AND decreased when CG was increased by the 12% SL. According to these results was established that SL affects DE value of CG and the nitrogen metabolism in pigs.

Keywords: Energy, Crude Glycerin, Starch