Evaluation of the chemical composition and energy values of expeller/ cold-pressed canola fed to growing pigs
Date
2023-03-29
Authors
Omotosho, Oluwakemi
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Abstract
There is rising importance in the use of expeller/ cold-pressing method to produce canola oil from its seed. This method leads to the presence of residual oil in the expeller/ cold-pressed canola (ECPC) making it a potential source of protein and energy for pigs. Although in this method canola seed is not heat and moisture treated as it is in the conventional pre-press solvent extraction, the differences in processing steps contribute to the variation in chemical composition and energy value of ECPC. Thus, determination of energy content of ECPC for swine and establishing correlation with its chemical components was the goal of this research. A detailed chemical composition of ECPC samples from five different processing plants was conducted. Results confirmed a variation in nutrient composition of ECPC among processing plants. The crude protein (CP), ether extract (EE), neutral detergent fibre (NDF) and glucosinolates (GLS) content of expeller/ cold-pressed canola ranged between 351.4 – 419.4g/kg, 84.9 – 177.2g/kg, 230.7 – 300.1g/kg and 5.0 – 9.7 μmol of total GLS/g, respectively (DM basis). Two metabolic studies with growing pigs were conducted to determine the energy values of ECPC and to explore how they are correlated with the nutrient composition. The first study was conducted to determine digestible energy (DE) and metabolizable energy (ME) of ECPC for growing pigs. Result showed the presence of greater residual oil in ECPC and its influence on DE and ME content. The goal of the second experiment was to determine the net energy (NE) content of different ECPC samples for growing pigs and compare the determined NE values using indirect calorimetry (IC) with predicted NE using published prediction equations. The NE of ECPC A, B, C, D and E determined using IC were 2,478, 3,058, 2,586, 2789, 3218 kcal/kg (DM basis), respectively, and these values were 2.3, 15.3, 10.2, 9.5 and 16.8% higher, respectively, compared with those estimated using prediction equations. However, significant differences were observed between determined and predicted values for only ECPC B, C, D and E. In general, ECPC contained an average of 3,531, 3,172, 2,826 and 2,507 kcal/kg, DE, ME, NE and predicted NE, respectively on DM basis. In conclusion, ECPC is a valuable source of energy in pig diets. The difference in processing technology within cold pressing method is a major source of variation in the chemical composition and energy values of ECPC. The residual oil in ECPC is an important contributor to its energy concentration.
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Keywords
expeller/ cold-pressed canola, digestible energy, metabolizable energy, net energy, pigs