NUTRIENT DIGESTIBILITY AND PROTEIN-QUALITY OF OATS DIFFERING IN CHEMICAL-COMPOSITION EVALUATED IN RATS AND BY AN IN-VITRO TECHNIQUE

The relationship between a number of chemical components and the nutri tive value of 15 oat samples was studied in vivo with rats and in vitr o with an enzymatic method. Also the effects of varying crude protein (CP) content, of oat samples on amino acid (AA) pattern and protein qu ality were studied. The content of total fibre was calculated as the r esidual fraction after substraction of the analysed content of sugars, starch, CP, crude fat and ash from the dry matter content. There were significant negative correlations (r = - 0.52 to -0.74) between total fibre and in vivo true N digestibility (TND), digestibility of energy (DE)(P < 0.01), biological value (BV) and net protein utilisation (NP U)(P < 0.05). Positive correlations (r = +0.61 to +0.65) were also fou nd between starch content and BV (P < 0.05) and NPU (P < 0.01). The in vitro total tract DM digestibility and in vitro ileal DM digestibilit y were negatively correlated to total fibre(P < 0.01) and positively c orrelated to starch content and DE(P < 0.01), respectively. The in vit ro total tract and ileal CP digestibility correlated positively to lev els of CP (P < 0.05 and P < 0.001, respectively) and soluble beta-gluc ans (P < 0.001 and P < 0.01, respectively). There were significant rel ationships between CP of oats and the content in CP of cysteine, methi onine + cysteine, histidine (P < 0.001), serine, glycine (P < 0.01), a spartic acid and tyrosine (P < 0.05). However, with the exception of p henylalanine (P < 0.05), the variation in AA composition did not affec t BV.