To estimate nutrient and energy digestion with animal from in vitro variables it is necessary to control factors that may interfere on digestion such as: source and concentration of digestor substance, as well as the origin and processing of test ingredients. In this study there were performed five laboratory assays, two with poultry and finally regression equations were established based on variables generated with twelve vegetable ingredients. The results showed that there is greater solubility of proteins with NaOH than with KOH. On average, both alkali produced better discrimination of soluble protein with concentration of 0.02% (range of 68.61%) in relation to a concentration of 0.2% (range of 37.97%). Considering interaction between alkali and concentration, the best discrimination on protein solubility was reached with NaOH at 0.02%. The methods of protein or fiber solubilization together with the chemical analysis showed significant results variation among ingredients and when they were used to estimate in vivo variables they produced good estimates. It was concluded that reliable digestion estimates for energy or amino acids from vegetable feed ingredients could be obtained from in vitro variables, when considering solubilities of protein and fiber with chemical analysis.
prediction equations; energy; total dietary fiber; nitrogen solubility; fiber solubility; alkali digestion; pepsin digestion
