Potential for improved utilization of canola meal by monogastric animals
The purpose of this reseach was to explore the potential for improved utilization of canola meal by monogastric animals. In study one, 26 yellow-seeded and 7 brown-seeded Brassica genotypes were evaluated for differences in chemical composition and dietary fibre profiles. On average, in comparison to brown-seeded, yellow-seeded genotypes contained more sucrose (8.7% vs 7.5%) and protein (44.5% vs 42.7%) and less dietary fibre (28% vs 33%). Dietary fibre was negatively correlated (r=-0.71) with protein content and its reduction in yellow-seeded samples was attributed to lower contents of lignin and polyphenols, cell wall protein and minerals associated with the fibre fraction. In a second study, selected Brassica genotypes were analyzed for digestible protein, soluble fibre, content of soluble phenolics and extract viscosity. Despite only minor differences in soluble fibre, soluble phenolics and extract viscosity, B. rapa and B. napus species had relatively high digestible protein content in comparison to B. juncea and B. carinata species. The measurements of digestible protein and dietary fibre as well as soluble phenolics and extract viscosity were poorly correlated. Based on chemical composition and digestible protein content, four Brassica cultivars were selected for use in a third study and the seeds were processed under optimal moist heat treatment conditions (108 + 1oC for 20 min). The samples included yellow-seeded B. rapa (cv. Parkland), B. rupus (cv. Y1016) and B. juncea (J4316) and brown-seeded B. rapus (cv. Excel). With the exception of B. rapa, all samples had higher than commercial meals protein content with the yellow-seeded B. napus canola showing the highest true metabolizable energy value. The overall performance of broiler chickens fed the Brassica seed meals was similar to that of the commercial meal from yellow-seeded canola (control) except for B. juncea which had a relatively high content of undesirable aliphatic glucosinolates. Of the diets with comparable growth performance, birds fed the yellow-seeded B. napus canola showed the highest feed efficiency value. In a forth study an attempt was made to improve the utilization of canola meal by supplementation of broiler chicken diets with exogenous enzymes. A positive and synergistic effect was noted when a combination of protease, carbohydrase and phytase enzymes were supplemented to canola meal-based diets deficient in available phosphorus.