Abstract
Context Canola meal is a protein-rich feedstuff with an amino acid profile that is reasonably well balanced and has the potential to replace soybean meal in poultry diets. Aim The objective of the present study was to investigate the relationship between the crude protein content and apparent ileal digestible amino acid contents of Australian canola meals. Methods Thirteen canola meal samples, processed by expeller or solvent extractions, were collected. The digestibility assay diets were based on dextrose and contained canola meal as the sole source of protein. The proportions of dextrose and canola meal were varied in each diet to obtain ~200 g/kg crude protein. Each diet was fed to three cages of six 35-day-old broilers for 7 days. At the end of the assay, digesta from the terminal ileum was collected for digestibility determination. Key results Crude protein contents were positively correlated with amino acid contents (P < 0.05 to 0.001), except that of serine (r = 0.43; P = 0.11). Significant correlations between the crude protein content and ileal digestible contents were observed for most of amino acids, with coefficients of >0.80 (P < 0.05 to 0.001). Low correlation coefficients were observed for lysine (r = 0.48; P = 0.11) and serine (r = 0.55; P = 0.06). The poor correlation for lysine may be reflective of reduced lysine availability during processing. Conclusions The results showed that the crude protein content of canola meal could serve as a predictor of apparent ileal digestible content of most amino acids for broiler chickens. Implications Regression equations developed in the present study could be used to predict the content of ileal digestible amino acids in canola meal by using analysed crude protein contents.